Dissertations / Theses: 'IMPACT OF RAINFALL'

1

Mehrotra, Rajeshwar Civil &amp Environmental Engineering Faculty of Engineering UNSW. "Multisite rainfall stochastic downscaling for climate change impact assessment." Awarded by:University of New South Wales. Civil and Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/23327.

Full text

Abstract:

This thesis presents the development and application of a downscaling framework for multi site simulation of daily rainfall. The rainfall simulation is achieved in two stages. First, rainfall occurrences at multiple sites are downscaled, which is followed by the generation of daily rainfall amounts at each site identified as wet. A continuous weather state based nonparametric downscaling model conditional on atmospheric predictors and a previous day average rainfall state is developed for simulation of multi site rainfall occurrences. A nonparametric kernel density approach is used for simulation of rainfall amounts at individual sites conditional on atmospheric variables and the previous day rainfall amount. The proposed model maintains spatial correlation of rainfall occurrences by simulating concurrently at all stations and of amounts by using random innovations that are spatially correlated yet serially independent. Temporal dependence is reproduced in the occurrence series by conditioning on previous day average wetness fraction and assuming the weather states to be Markovian, and in the amount series by conditioning on the previous day rainfall amount. The seasonal transition is maintained by simulating rainfall on a day-to-day basis using a moving window formulation. The developed downscaling framework is calibrated using the relevant atmospheric variables and rainfall records of 30 stations around Sydney, Australia. Results indicate a better representation of the spatio-temporal structure of the observed rainfall as compared to existing alternatives. Subsequently, the framework is applied to predict plausible changes in rainfall in warmer conditions using the same set of atmospheric variables for future climate obtained as a General Circulation Model simulation. While the case studies presented are restricted to a specific region, the downscaling model is designed to be useful in any generic catchment modelling and management activity and/or for investigating possible changes that might be experienced by hydrological, agricultural and ecological systems in future climates.

APA, Harvard, Vancouver, ISO, and other styles

2

Bistritschan, Torsten. "Impact of moisture flux corrections on seasonal predictability of African rainfall." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400554.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Sonder, Kai. "Soil erosion in andean cropping systems : the impact of rainfall erosivity." Hohenheim : Universität Hohenheim, Institut für Pflanzenproduktion und Agrarökologie in den Tropen und Subtropen, 2004. http://opus-ho.uni-stuttgart.de/hop/volltexte/2004/55/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Farnsworth, Alexander James. "Rainfall variability and the impact of land cover change over central Africa." Thesis, University of Reading, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.654486.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Panikom, Nattawadee. "Climate Change Impact on Rainfall-Induced Landslides in Ottawa Sensitive Marine Clays." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/41041.

Full text

Abstract:

The City of Ottawa is situated in an area known as the Champlain Sea, 17,000 years before present (BP) the entire area was covered with sea water. This area deposited marine clays which are known to be highly sensitive. The City of Ottawa needs to expand land use to allow for the expansion of infrastructure and housing to support its growth. This study is intended to assist the City of Ottawa’s geotechnical engineers in their decision-making by identifying future sensitive areas prone to landslides due to rainfall based on future climate model data. The project incorporates rainfall intensities from downscaled climate model data in the Transient Rainfall Infiltration and Grid-based Regional Slope-Stability (TRIGRS) model to investigate areas sensitive to landslides, then within a GIS platform, the future landslide susceptibility maps were created based on Factor of Safety (FS) values showing the areas prone to landslides. The data input for the model includes climate model data, topography, hydrogeology, geology and geophysical data obtained from a previous study. These data were prepared using ArcGIS software and converted into ascii format for TRIGRS model. The model was calibrated using historical rainfall intensities and validated by comparing to historical landslide areas. Sensitivity analysis were performed to ranges of geotechnical properties found within sensitive marine clays in the area to find the values best to create the ideal scenario, normal scenario and worst-case model scenario for the prediction. Rainfall intensities from projected climate data Intensities Duration Frequency (IDF) of 10 years and 50 years returning period and rainfall intensities of 12 hr, 24 hr, and 48 hr were selected for the model. Results from simulations find the projected climate rainfall intensity do not have impact or has minimal impact to slope stability in sensitive marine clay areas in Ottawa directly. However, higher rainfall runoff is expected from projected rainfall RCP8.5 than the RCP4.5. The infiltration rate remains constant throughout each simulation, which is the same value as the hydraulic conductivity. The time when the slope becomes unstable varies depending on initial water levels. Results from the ideal and normal scenario show no areas prone to slope failure after 48 hours of rainfall duration. However, the factor of safety decreases as the rainfall duration increases and is expected to decrease with longer rainfall durations. The worst-case scenario shows some areas prone to slope failure (FS < 1) with 2% probability of slope failure at 48 hours of rainfall duration. The distribution of these unstable areas are located along the Ottawa River, Rideau River, Carp River, Mississippi River and valleys along their tributaries, the majority of the area prone to slope instability from rainfall are in the east part of the City of Ottawa. While there are many uncertainties and limitations which contribute to the model results, this study is useful to engineers and planners in initial implementation of mitigation strategies to mitigate the damages and cost from landslides events. The susceptibility maps can also assist in decision making for planners in developing into these areas.

APA, Harvard, Vancouver, ISO, and other styles

6

Collins, Robert Peter. "The impact of terraced agriculture upon water quality in the Middle Hills, Nepal." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340011.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Pal, Indrani. "Rainfall trends in India and their impact on soil erosion and land management." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/224798.

Full text

Abstract:

Under the threat of global warming it is vital to determine the impact that future changes in climate may have on the environment and to what extent any adverse effects can be mitigated. In this research an assessment was carried out on the impact that climate trends may have on soil erosion and contaminant transport in India and examined the potential for top soil management practices to improve or maintain soil quality. Historical rainfall data from 50-135 years and extreme temperature data for 103 years were analysed and long term trends were assessed for various aspects of Indian climates using suitable statistical techniques. Results indicated that intra-region variability for extreme monsoon seasonal rainfall is large and mostly exhibited a negative tendency leading to increasing frequency and magnitude of monsoon rainfall deficit and decreasing frequency and magnitude of monsoon rainfall excess everywhere in India except in the peninsular Indian region. This is further exacerbated by increased and more variable extreme temperatures. Intra-region rainfall variability in India is linked to the pacific Southern Oscillation, where the associations of monsoon drought and El-Niño Southern Oscillation (ENSO) in the regions near to coast are greatest. 50-years high resolution daily gridded rainfall data was analysed to set up certain indices for the extreme daily rainfalls to assess their changes for the six gridded regions of Kerala, the extreme south western state of India where monsoon rainfall initiates every year. This was also done for two study sites, namely Bhoj wetland area of west central India and Sukinda chromite mining site of central north east India. Significant decrease was found in monsoon and spring rainfall extremes and increase in winter and autumn rainfall extremes in Kerala that would affect the tendency of change in seasonal total rainfall as well. Decrease in monsoon rainfall in Kerala also indicate that monsoon rainfall is decreasing in India as a whole, increased occurrence of floods is expected in winter and autumn seasons, together with water scarcity are expected to be felt both in spring and monsoon seasons with a delaying monsoon onset in Kerala. Soil erosion studies were conducted for two northern most gridded regions of Kerala as an extended work of the related MPhil study, and contaminant transport with eroded sediments was looked at for the Bhoj and Sukinda sites using RUSLE2 model software and other suitable numerical methods. It was found that soil erosion depended on a complex interaction of climate, soil properties, topography, and cover management. An assessment on extreme climate patterns for Bhoj and Sukinda showed an increasing tendency of seasonal and annual rainfall extremes and temperatures leading to an increasing pattern of soil erosion at both the sites. However, a certain consensus was difficult to reach because of the complex interaction of climate and soil carbon that is a very important deciding factor for soil erosion potential. Vegetative cover and plant residue was found providing essential soil nutrients, enhancing soil properties and retarding rainfall impact on bare top soil leading to reduction of soil erosion. Therefore, a soil erosion and contaminant transport prevention plan should take care of the top soil such that it is not kept bare especially when rainfall intensity is high in a given year. This work as a whole has highlighted the importance of regional climatological analysis with the large scale spatial averages especially at local decision making level, which is very useful for the broad scenarios such as climatological and ecological risk management.

APA, Harvard, Vancouver, ISO, and other styles

8

Chen, Yi-Ru. "Impact Assessment of Climate and Land-Use Changes on Rainfall and Flood Runoff." Thesis, Griffith University, 2014. http://hdl.handle.net/10072/366232.

Full text

Abstract:

Worldwide, flooding is a common environmental hazard, and is also one of the major natural hazards that can cause death and economic losses in Australia. Flooding is the overflow of water onto normally dry land and is often caused by a prolonged period of rainfall, high-intensity/short-duration storms, or storm surges associated with tropical cyclones or other intense low pressure systems. Climate and weather, land-use, and social processes all have an influence on the occurrence of floods and their impacts. In particular, urbanisation, with a noticeable increase in impervious area, is a significant cause of increased flood volume and peak discharge. The magnitude and frequency of occurrence of floods as impacted by global warming and land-use change have been previously investigated. General Circulation Models (GCMs) have been used to derive climate projections. The uncertainty with climate projections based on GCM outputs is usually a concern, whereas examination and analysis of historical long-term rainfall data can provide an improved understanding of past climate change and help develop likely future climate change scenarios. The majority of research so far has examined changes in annual, seasonal, monthly, and daily rainfall. However, to date only limited work has considered the changes in sub-daily rainfall intensities in south-eastern Australia.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text

APA, Harvard, Vancouver, ISO, and other styles

9

Bidin, Kawi. "Spatio-temporal variability in rainfall and wet-canopy evaporation within a small catchment recovering from selective tropical forestry." Thesis, Lancaster University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369023.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Bhowmick, Mansi. "Impact of soil moisture variability on convective rainfall activity over the Indian sub-continent." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/17015/.

Full text

Abstract:

Soil moisture is an important geophysical parameter affecting land atmosphere processes, and hence free convection, by controlling the partitioning of the surface heat flux into latent and sensible heat flux. Interaction between these fluxes and the atmosphere gives rise to different types of soil moisture-precipitation feedback, namely “wet advantage” where rain is favoured over a wet (high latent heat flux) surface and “dry advantage” where rain is favoured over a dry (high sensible heat flux) surface. Previous studies over different parts of the world have shown that these feedback processes can take different pathways, according to one-dimensional and three-dimensional models. According to the one-dimensional model there is probability of rain initiation when the boundary layer top meets the level of free convection either by heating (increase in sensible heat flux over a dry surface) or by moistening (increase of latent heat flux over wet soil) of the boundary layer. On the other hand three-dimensional models explain convective triggering due to wind convergence near gradients in soil moisture. This is a first study to compare and evaluate the existing soil moisture-precipitation feedback theories presented in the literature, over the Indian sub-continent under a single environment, by using high resolution convection-permitting (non-parameterized, or “explicit” convection) EMBRACE model simulation. Initially, a brief synoptic observational study shows evidence of surface-atmosphere coupling. More detailed case studies from the model output show further evidence for the land-atmosphere interaction in this region. The model indicates that all the processes defined by different theoretical models do exist under different surface, and atmospheric conditions. The relative contribution of different processes under different soil moisture conditions prevailing over different climatic zones of the Indian sub-continent during the 20-day wet monsoon period from mid-July to early August is statistically studied. Dry-to-wet downwind soil moisture gradient is found to be the statistically significant pattern for initiation of the majority of afternoon convective initiation in the East, Centre and South study domains of India. It is also found that the so-called “CTP-HIlow” predictive framework is not sufficient to address the observed behaviour of convective initiation under the full three-dimensional modelling environment. The use of the parameter HIlow, which is defined as the sum of humidity within and just above the inversion, as a predictive parameter is not physically understandable. This framework also lacks generality and solutions are empirically derived based on one-dimensional modelling and observations, which vary from place to place. To offer a solution to these theoretical difficulties, this study provides a new quantitative model, using the basic idea behind the CTP-HIlow framework to find new predictive parameters depending on sound physical relationships instead of empirical solutions. The system is governed by two non-dimensional parameters, namely inversion Bowen ratio and a “stiffness ratio”, and a third, dimensional parameter ΔR. Analysis of the EMBRACE simulations shows occurrence of both the dry and wet advantage, but the majority of the morning profiles favour prediction of dry advantage. Thus, the equations derived from the new quantitative model offer a quantitative prediction of wet and dry advantage occurring systematically, which is a question of great importance to weather and climate prediction, especially over moisture-limited areas.

APA, Harvard, Vancouver, ISO, and other styles

11

Boening, Kathryn Margaret. "Impacts of Green Infrastructure Practices and Rainfall Characteristics on Sewershed Hydrology and Water Quality." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595352797878418.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

roberts, john christopher. "Impact of Manure and Soil Test Phosphorus on Phosphorus Runoff from Soils Subjected to Simulated Rainfall." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-06162005-123000/.

Full text

Abstract:

Runoff from agricultural fields amended with animal manure or fertilizer is a source of phosphorus (P) pollution to surface waters, which can have harmful effects such as eutrophication. The objectives of this study were to evaluate the impact of soil P status and the P composition of manure sources on P in runoff, characterize the effects of manure sources on mass loss of dissolved reactive P (DRP), total dissolved P (TDP), algal available P (AAP) and total P (TP) in runoff, and enhance the PLAT database with respect to soluble P attenuating factor (SPAF) and non-soluble P attenuating factor (NSPAF) values. Soil boxes set at 5% slopes received 7.5 cm hr-1 of simulated rainfall. Study soils included a Kenansville loamy sand (loamy siliceous subactive thermic Arenic Hapludults, a Coastal Plain soil) and a Davidson silt loam (kaolinitic thermic Rhodic Kandiudults, a Piedmont soil). Soil test P concentrations ranged from 16 to 283 mg P kg-1. Sources of P included broiler litter (BRL), breeder manure (BRD), breeder manure treated with three rates of alum (Al2(SO4)3) BRD0-0 kg m-2, BRDL-3.9 kg m-2, and BRDH-7.8 kg m-2 and DAP along with an unamended control. All manure sources were applied at 66 kg P ha-1. Water extractable P (WEP) represented an average of 10 ?b 6% total P in manure. Runoff samples were taken over a 30-min period. Piedmont soil contained greater amounts of clay, Al and Fe concentrations, and higher P sorption capacities that produced significantly lower DRP, TDP, AAP, and TP losses than the Coastal Plain soil. Runoff P loss did not differ for low and high STP soils of same taxonomy with the exception of AAP mass losses for Coastal Plain soil samples. Water extractable P in manures accounted for all DRP lost in runoff with DRP correlating strongly with WEP concentration (0.9961). A weak relationship between DRP in runoff and WEP applied to soil boxes was observed (R2=0.6547) and increased when a possible outlying manure treatment, BRL, was omitted from regression data (0.9927). Overall, manures containing the highest WEP concentrations supplied the largest losses of DRP in runoff. Manure treated with 3.9 and 7.8 kg m-2 of Al2(SO4)3 (alum) decreased DRP in runoff by 29%. Values calculated for PLAT SPAF and NSPAF coefficients were higher for Coastal Plain soil than Piedmont soil and overall higher than default values in PLAT. Management based on these results should help minimize harmful effects of P in runoff.

APA, Harvard, Vancouver, ISO, and other styles

13

Almeida, Ivan Rodrigues de [UNESP]. "O clima como um dos fatores de expansão da cultura da soja no Rio Grande do Sul, Paraná e Mato Grosso." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/105089.

Full text

Abstract:

Made available in DSpace on 2014-06-11T19:33:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-12-13Bitstream added on 2014-06-13T20:45:26Z : No. of bitstreams: 1 almeida_ir_dr_prud.pdf: 4783228 bytes, checksum: 01b142e4a91f41fa98a34f86ee70e911 (MD5)
O clima pode ser considerado como um dos componentes mais importantes do ambiente ao estabelecer limite às atividades humanas e à sua organização na superfície da Terra. Entre essas atividades, a agricultura exerce papel fundamental ao produzir alimentos e garantir o comércio entre as nações por intermédio da produção de excedentes. A cultura da soja coloca o Brasil no mercado internacional como o segundo maior produtor mundial, e com a participação interna liderada pelos estados do Mato Grosso, Paraná e Rio Grande do Sul. A hipótese do presente trabalho sugere que as diferentes condições climáticas no território brasileiro têm favorecido a migração dos pólos de produção até então concentrados na Região Sul para a Região Centro-Oeste, produzindo impactos ambientais e acentuando desigualdades sociais. No desenvolvimento dos objetivos constatou-se essa afirmativa avaliando-se as condições da distribuição fundiária e da produção, caracterizando a menor variabilidade da pluviosidade no estado do Mato Grosso, bem como o regime e distribuição da pluviosidade, por intermédio de técnicas de geoprocessamento e da elaboração de um sistema de análise e consulta baseado nos recursos de navegação da internet, disponível em http://www.ivanrdea.pop.com.br.
Climate can be considered as one of the most important environmental component establishing boundaries to human activities and its organization on earth surface. Among these activities, agriculture play an important role producing food and to guarantee the commerce of exceeding production among nations. In the international market Brazil is considered as the bigger world-wide soybean producer, with the internal participation led by Mato Grosso, Paraná, and Rio Grande do Sul states. The hypothesis of our work suggests that the different climatic conditions in the Brazilian territory has benefited the migration from the major production regions, until then concentrated in the South Region, to the Center-West region. This migration caused environmental impacts and enhanced social inequalities. In the development of our study this statement was proved when the conditions of the agrarian distribution and the production was analyzed, characterizing low rain variability in Mato Grosso state, as well as the regimen and rainfall distribution, by geoprocessing techniques and the development of an analysis and consultation system based on the resources of navigation through the world wide web, available at http://www.ivanrdea.pop.com.br.

APA, Harvard, Vancouver, ISO, and other styles

14

Raath, Gideon. "The impact of high rainfall and flood events on Eucalyptus camaldulensis distribution along the central Breede River." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97021.

Full text

Abstract:

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Eucalyptus camaldulensis Dehnh., or River Red Gum, is a commercially valuable yet recognised invasive alien plant (IAP) of riparian zones throughout South Africa. The invasive potential of E. camaldulensis is widely recognised, with specific regulations aimed at the management of E. camaldulensis. E. camaldulensis is known to use large amounts of water, reduce biodiversity, change river morphology and impact hydrological regimes of rivers. In the native range throughout Australia, E. camaldulensis displays a distinct relationship between rainfall, and flood events, for seed dispersal, germination and establishment, and consequently spatial extent, yet little is known about the relationships in the South African context. The aim of this project was to assess the impact of high rainfall and flood events on the establishment and distribution of E. camaldulensis along the Middle Breede River, between Worcester and Swellendam in the Western Cape, by establishing the current spatial extent of E. camaldulensis along the river, identifying flood events since 1950 and evaluating the impact rainfall and flood events had on the spatial extent thereof. Aerial imagery, rainfall, discharge and river level data was obtained dating back to 1980, as well as field data comprising of GPS-bounding of E. camaldulensis stands. Additionally, density measurements were obtained and interviews conducted with land users. Spatial analysis of aerial imagery, coupled with perimeter (GPS) data and density data were used to conduct spatio-temporal analysis, employing GIS and conventional statistical approaches to address the various objectives. Results indicated E. camaldulensis stands had a small overall increase in spatial extent since 1980. Flooding and rainfall events coincided with an increase in occurrence of E. camaldulensis with elevated river levels and frequent flooding, while spatial variation of this relationship was observed. The hydrological regime of the Breede River coincides with a slow increase in spatial extent of E. camaldulensis stands, but no affirmation of a positive real-world relationship was possible using the available data. Results further suggested, based on the current age class composition, that existing stands originated roughly during 1980, possibly due to commercial forestry related seeding into the river. Reduced fragmentation between stakeholders, educational programmes and improved reporting systems were recommended for improved IAP management within the area.
AFRIKAANSE OPSOMMING: Eucalyptus camaldulensis, of Rooibloekom (RB), is ‘n waardevolle kommersiële, maar erkende indringer plantspesie (IP) wat veral oewersones in Suid-Afrika indring. Die indringerpotensiaal van E. camaldulensis is welbekend, en spesifieke regulasies, gemik op die bestuur van RB en ander spesies is reeds aangeneem. E. camaldulensis is veral bekend vir sy hoë watergebruik, sy vermindering van biodiversiteit, sy vermoë om riviervorme te verander en sy algehele impak op die hidrologiese patroon van riviere waarmee dit in aanraking kom. In sy oorspronklike verspreidingsgebied in Australië toon E. camaldulensis ‘n bepaalde verhouding tussen reënval en vloedgebeurtenisse vir saadverspreiding, ontkieming en vestiging en derhalwe die ruimtelike verspreiding van die spesie; alhoewel hierdie verhouding in die Suid-Afrikaanse konteks steeds redelik onverduidelik bly. Die doelwit van hierdie studie was dus om die impak van hoë reënval en vloedgebeurtenisse op die ruimtelike verspreiding en vestiging van E. camaldulensis teenaan die Middel Breëde Rivier, spesifiek tussen Worcester en Swellendam, te evalueer. Hierdie doelwit was bereik deur die historiese ruimtelike verspreiding teenaan die rivier te meet, hoë reënval en vloedgebeurtenisse vanaf 1980 te identifiseer, en die huidige verspreiding en omtrek met GPS te meet. Digtheidafmetings, sowel as onderhoude met belanghebbendes teenaan die rivier was ook opgeneem. Visuele interpretatasie van lugfotos, sowel as omtrek (GPS) en digtheid-data was gebruik om ruimtelike analise uit te voer, deur die gebruik van GIS en konvensionele statistiese metodes, ten einde die doelwitte te evalueer. Resultate dui aan dat E. camaldulensis areas ‘n klein algemene groei getoon het sedert 1980. Hoë-reënval en gereëlde vloedgebeurtenisse het ook gepaard gegaan met ‘n groei van E. camaldulensis oppervlak, alhoewel hierdie verhouding ruimtelike variasie getoon het, met ‘n algemene groei patroon gemerk oor die volledige studietydperk. Ook geen stimulerende verhouding kon vanuit die beskikbare data bevestig word nie. Addisionele resultate het aangedui dat die verspreiding van E. camaldulensis ongeveer 1980 onstaan het, moontlik as gevolg van kommersiële bosbou-aanplanting en verwante saadverspreiding in die rivier vanaf daardie tyd. Aanbevelings ten opsigte van verbeterde indringerbestuur sluit in die beperking van huidige fragmentasie tussen belanghebbendes en betrokke verwyderingsorganisasies, addisionele onderrigprogramme sowel as die verbetering van terugvoersisteme.

APA, Harvard, Vancouver, ISO, and other styles

15

Wi, Sungwook. "Impact of Climate Change on Hydroclimatic Variables." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/265344.

Full text

Abstract:

The conventional approach to the frequency analysis of extreme rainfall is complicated by non-stationarity resulting from climate change. In this study significant trends in extreme rainfall are detected using statistical trend tests (Mann-Kendall test and t-test) for all over the Korean Peninsula. The violation of the stationarity for 1 hour annual maximum series is detected for large part of the area especially for southwestern and northeastern regions. For stations showing non-stationarity, the non-stationary generalized extreme value (GEV) distribution model with a location parameter in the form of linear function of time makes significant improvement in modeling rainfall extremes when compared to the stationary GEV model. The Bartlett-Lewis rainfall model is used to generate annual maximum series for the purpose of generating the Intensity-Duration-Frequency (IDF) curve. Using 100 sets of 50 year synthetic annual maxima, it is found that the observed annual rainfall maximum series are reasonably represented by the model. The observed data is perturbed by change factors to incorporate the climate change scenario from the WRF (Weather Research and Forecasting) regional climate model into IDF estimates. The IDF curves for the future period 2040-2079 show highest estimates for all return periods and rainfall durations. The future IDF estimates show significant difference from the IDF estimates of the historical period (1968-2000). Overall, IDF curves show an increasing tendency over time. A historical and future climate simulation is evaluated over the Colorado River Basin using a 111-year simulation (1969-2079) of the WRF climate change scenario. We find the future projections show statistically significant increases in temperature with larger increases in the northern part of the basin. There are statistically insignificant increases in precipitation, while snowfall shows a statistically significant decrease throughout the period in all but the highest elevations and latitudes. The strongest decrease in snowfall is seen at high elevations in the southern part of the basin and low elevations in the northern part of the basin.

APA, Harvard, Vancouver, ISO, and other styles

16

Cretin, Curtis J. "Impact of ethanol plants on Kansas land values." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/20576.

Full text

Abstract:

Master of Agribusiness
Department of Agricultural Economics
Allen Featherstone
Land values have a fascinating history after the first settlers started moving west in the 19th century. Much research has been done in agricultural economics with regards to land values and this subject will continue to be watched closely as we move further into the 21st century. The goal of this thesis is to understand the effect that ethanol plants have on the price of land around the ethanol plant. More specifically, the thesis addresses the question of “What impact do ethanol plants have on Kansas Land values?” The thesis also answers the question of “Are land values directly correlated to the proximity of an ethanol plant and if they are directly correlated, to what extent or how much more valuable is a parcel of land that is 30 miles to an ethanol plant compared to a parcel of land that is 70 miles?” As we move into the 21st century, the nation continues to look for alternative fuel sources. Ethanol produced from corn has played a key role in that search for an alternative fuel. In 2007, the state of Kansas proposed to have 29 ethanol plants built and/or operational in the near future. The majority of the ethanol plants were built in 2006 and 2007 with only 16 of those plants becoming operational. This thesis uses those 16 ethanol plants as the basis of this study. The study determines if land sale values from 2010 to 2013 were directly impacted based on the proximity to the closest ethanol plant. Corn is the main crop used in this study with regards to the production of ethanol. While other crops can be used to produce ethanol, the study only focused on the corn crops from 2010 to 2013. The trend in cash corn prices and basis data reflects the advent of the development of ethanol plants with a cash corn high of $8.05 in 2012 and a basis high of $1.84 above futures prices in 2013. In addition to cash corn prices and basis data, the study also collected land parcel sales from the years 2010 to 2013 with 9,279 total observations. Utilizing regression, an equation was estimated taking into account land price, size of land parcel sold in acres, quarter of year for sale, a year binary variable, the minimum distance of an ethanol plant to each parcel sale, the percent pasture acres, percent irrigation acres, rainfall, cropland productivity, and population density. Results indicated that land closer to an ethanol plant is priced at a premium compared to land further away. Land values will continue to be closely studied as we move into the 21st century. This study was able to provide a price point per mile of how much more valuable a land parcel is the closer it is located to an ethanol plant. While this study only factored in the closest ethanol plant to that land parcel sale, other factors such as including multiple ethanol plants located in the same town or ethanol plants that are close in proximity to each other could be further analyzed to continue research on this topic.

APA, Harvard, Vancouver, ISO, and other styles

17

com, aeveraardt@hotmail, and Annika Everaardt. "The impact of fire on the honey possum Tarsipes rostratus in the Fitzgerald River National Park, Western Australia." Murdoch University, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040611.105120.

Full text

Abstract:

The honey possum Tarsipes rostratus is a tiny (7 - 12 g) highly specialised flower-feeding marsupial endemic to the south-western corner of Australia. The impact of fire on this small mammal was studied, over a 19-year period, in the Fitzgerald River National Park, a large (330,000 ha) area of relatively undisturbed heathland/shrubland, rich in the proteaceous and myrtaceous plants upon which the honey possum appears to rely for food. The honey possum is the most abundant and widespread mammal in this Park. Capture rates of honey possums were significantly related to the years since the vegetation was last burnt, annual rainfall in the preceding (but not the current) year, the season when trapping occurred, and the trapping grid operated. Capture rates declined markedly after fire and remained low (less than one third of those in long unburnt vegetation) for about 4 - 5 years following a fire. Rates of capture then increased steadily over the next 20 - 25 years, with maximal abundance recorded about 30 years after fire. Thereafter, there appeared to be a slight decline in capture rates, but even in the vegetation unburnt for longest (> 50 years since fire), honey possum abundance was substantial and relatively stable. In contrast to these changes in abundance, the structure of the honey possum population, with 79 % adults and 57 % males, appeared little influenced by fire history, annual rainfall, season or grid. The increase in the rates of capture of honey possums following fire paralleled the pattern of availability of cover in the vertical and, to a lesser extent, horizontal plane. Indeed, projective foliage cover took around 20 years after fire to reach levels similar to those available in areas unburnt for even longer. The trend in capture rates was also congruent with the maturation of the most frequently visited foodplants of honey possums, particularly Banksia nutans (summer flowering) and B. baueri (winter flowering). Areas long unburnt still contained shelter and foodplants adequate for honey possums even 50 years or more after fire, with only slight evidence of senescence. Pollen loads indicated that honey possums caught in burnt areas, where their preferred foodplants were absent, continued to feed on these favoured foodplants (Banksia and Dryandra spp.) at nearby unburnt areas. In addition, they also fed, in both burnt and long unburnt areas, upon a suite of other plant species that regenerated more rapidly from lignotubers and epicormic buds, as well as from seeds (e.g. Eucalyptus and Calothamnus spp.). Thus, honey possums appeared to persist with their preferences for feeding from a limited number of flowering plants despite some of these species not being available in recently burnt areas for many years. Nearby patches of unburnt vegetation can clearly be important refuges, feeding grounds and shelter for the few honey possums that visit recently burnt areas, and appear to be the source of honey possum colonists in the years following a fire. Capture rates were also greater following years when rainfall was higher than average. Indeed, rainfall had as great an influence upon capture rates as time since fire. Capture rates were also consistently higher over winter, and to a lesser extent over summer, than in either autumn or spring. Individual grids, even those close together in apparently similar vegetation with a similar fire history, still differed significantly overall in their capture rates of honey possums. This last finding has implications for the use of chronosequences in the study of post-fire changes in biota. Although not the primary focus of the study, data on the limited suite of other, far less abundant, small mammals present indicated that house mouse Mus musculus domesticus numbers peak soon after fire (about two years after fire), grey-bellied dunnart Sminthopsis griseoventer numbers somewhat later (about eight years after fire) and that southern bush rats Rattus fuscipes fiuscipes, like honey possums, are later successional species. Most species were present in vegetation over a range of post-fire ages, with data consistent with models based on sequential changes in relative abundance. Like many Australian mammals, the range of the honey possum has contracted substantially over the last 200 years and the coastal heathlands of the south-west are its last stronghold. In terms of its conservation, this study indicates that, if possible, management burns in these heathlands should be separated by intervals of at least 20 years between successive burns, and preferably even longer. If burns are required more frequently to meet other management priorities, it is highly preferable that they are small and patchy, rather than large scale. Such practices may help ensure the long-term survival of this unique, highly specialised and endemic marsupial.

APA, Harvard, Vancouver, ISO, and other styles

18

Razanatsoa, Estelle. "Impact of human land-use and rainfall variability in tropical dry forests of southwest Madagascar during the late Holocene." Doctoral thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/30450.

Full text

Abstract:

Over the last 2000 years, climatic and anthropogenic factors have influenced vegetation in Madagascar, but the contribution of these two factors has been the subject of intense debate, a debate hampered by the scarcity of palaeoecological studies on the island. Southwest Madagascar is semi-arid and comprises fragmented tropical dry forests where human subsistence strategies are diverse. Therefore, it provides a perfect setting to generate new palaeoecological records and investigate vegetation response to changes in human land-use and rainfall variability. The aim of this thesis is to understand how and when land-use changed, and rainfall variability impacted the landscape in the southwest region, using dendroclimatological and palaeoecological approaches. Carbon isotopes in the rings of four baobab trees (Adansonia spp.), were compared with pre-existing palaeoclimate data to produce rainfall records for the past 1700 years. Pollen, carbon isotopes, and charcoal in sediment cores from two lakes namely Lake Longiza and Lake Tsizavatsy (located in the northern and southern sites respectively in southwest Madagascar) were analysed to produce vegetation and fire records during the late Holocene in the region. Combination of the four baobab isotope records yields a new 700-year record for the southwest, which suggests an aridity trend over time, associated with a long-term reduction and increase in the duration of wet and dry periods respectively. Drying was more pronounced for the southern site than the northern site. A comparison with a high-resolution record from the northwest region allowed the rainfall of the southwest to be extended back to the last 1700 years as follows: from AD 300-500, the southwest region experienced a dry period which was followed by a wet period until AD 1000. Subsequently, there was a dry period from AD 1000-1250, followed by a wet period in the southwest. The period from AD 1300-1400 represented the wettest period in the record, followed by a decreasing wet period until AD 1600. The period between AD 1600 and 1800 represented the driest period, peaking around AD 1700. This was followed by a relatively wet period of about 50 years and another 100-year dry period. The last period assessed, from AD 1985 to 2000, was a relatively wet period. Such variability of the rainfall might have affected ecosystems and human land-use in the region. The tropical dry forest biome of southwest Madagascar has taxa from the dry forest, riparian forest and savanna woodland in the pollen records of both sites. In the core from the northern site (Lake Longiza), the pollen record suggests a heterogeneous mosaic of dry forest and riparian forest that was present over the last 2400 years. In the earliest part of the record, the community was dominated by trees from both the dry forest and riparian ecosystems. The onset of changes was recorded around AD 420, with a decrease in dry forest and riparian trees and an increase in grasses and xerophytics, possibly driven by dry conditions. This was followed by a short recovery of trees and C3 plants around AD 870 punctuated by a decrease in dry forest taxa around AD 980, possibly associated with the suggested expansion of pastoralism. After this period, the landscape became more open and grassier, as indicated by the dominance of C4 plants in the stable isotope record. Similar patterns of change in the pollen record, with a further increase in grasses and pioneer taxa, were recorded around AD 1900. Charcoal influx also started to increase drastically at this time, suggesting fire and forest clearance associated with a shift to agriculture. These large shifts in human land-use (probably a combination of both pastoralism and agriculture) coincided with the decline of floral diversity of the landscape, as indicated by pollen rarefaction. However, the diversity of the floral community gradually recovered, because of the persistent heterogeneity of the landscape. The core from the southern site (Lake Tsizavatsy) had a basal date of approximately 700 years BP but presented a hiatus of about 500 years from AD 1420-1910. The preceding period of AD 1300-1420 was marked by a decrease in the abundance of trees during the wettest period in the region, which was most likely because of human activities (foraging and pastoralism), as inferred by the increase in charcoal influx and pioneer taxa. During the second period, from AD 1910- 2010, there was an increase in xerophytic taxa, which suggests a long dry climate, recorded prior to this period. In addition, from AD 1950, trees decreased while pioneer taxa increased, despite the stable influx of charcoal recorded during this period. This possibly indicates the effect of human activities that did not involve the use of fire, probably conducted by ethnicities other than the forager communities, which are still present in the area today. This thesis contributes significantly to the understanding of palaeoclimate, palaeoecology and the history of human subsistence in a biodiverse region of Madagascar, where no other record is currently available. Results from stable isotope analysis from baobabs showed a drying trend over the past 700 years, which has interacted with land-use to affect vegetation structure and composition over time. The pollen and charcoal results suggest the northern site, where vegetation was a mosaic of dry forest and riparian forest, experienced an impact of human activities through a shift to agriculture especially in the last 100 years. The savanna woodland of the southern site, however, was less affected by humans, probably as occupants were subsistence foragers, but the vegetation had a higher response to aridity. The results show that two distinctive human subsistence (pastoralism and foraging) were present simultaneously in the region until modern times. The northern site has evolved possibly from foraging into extensive agriculture, probably related to the fertility of the alluvial soil in the area, while the southern community remained dominated by foragers, while adopting today a seasonal practice of agriculture. From a conservation perspective, strategies of conservation for each ecosystem investigated here are proposed. In the northern site, monitoring and reducing fire-use within the dry forest ecosystem would allow tree recovery. In addition, restoring and establishing protected areas within the riparian forest would allow these ecosystems to act as refugia for regional biodiversity. Such measures will likely reduce the pressure on these ecosystems, where agriculture is a threat due to the availability of both water and fertile soil in their surroundings. Alternative livelihoods are required for the northern populace, for example through the exploitation of invasive aquatic plants such as Typha, which can be used in making of handcrafted artefacts, to reduce pressure on forest ecosystems through agricultural practices. For the southern site, maintaining the resilience of the savanna woodland through reforestation of functional species is also important to allow sustainability of services provided by these ecosystems. These strategies are applicable locally for Madagascar and for worldwide tropical dry forests, one of the globally most threatened vegetation types due to anthropogenic pressure and climate change.

APA, Harvard, Vancouver, ISO, and other styles

19

Van, Wageningen Andries. "The impact of climate change on hydrological predictions with specific reference to 24-hour rainfall intensities in the Western Cape /." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/1275.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Almeida, Ivan Rodrigues de. "O clima como um dos fatores de expansão da cultura da soja no Rio Grande do Sul, Paraná e Mato Grosso /." Presidente Prudente : [s.n.], 2005. http://hdl.handle.net/11449/105089.

Full text

Abstract:

Orientador: João Lima Sant'Anna Neto
Banca: Antonio Nivaldo Hespanhol
Banca: José Renato Bouças Farias
Banca: Antonio Eduardo Pípolo
Banca: José Tadeu Garcia Tommaselli
Resumo: O clima pode ser considerado como um dos componentes mais importantes do ambiente ao estabelecer limite às atividades humanas e à sua organização na superfície da Terra. Entre essas atividades, a agricultura exerce papel fundamental ao produzir alimentos e garantir o comércio entre as nações por intermédio da produção de excedentes. A cultura da soja coloca o Brasil no mercado internacional como o segundo maior produtor mundial, e com a participação interna liderada pelos estados do Mato Grosso, Paraná e Rio Grande do Sul. A hipótese do presente trabalho sugere que as diferentes condições climáticas no território brasileiro têm favorecido a migração dos pólos de produção até então concentrados na Região Sul para a Região Centro-Oeste, produzindo impactos ambientais e acentuando desigualdades sociais. No desenvolvimento dos objetivos constatou-se essa afirmativa avaliando-se as condições da distribuição fundiária e da produção, caracterizando a menor variabilidade da pluviosidade no estado do Mato Grosso, bem como o regime e distribuição da pluviosidade, por intermédio de técnicas de geoprocessamento e da elaboração de um sistema de análise e consulta baseado nos recursos de navegação da internet, disponível em http://www.ivanrdea.pop.com.br.
Abstract: Climate can be considered as one of the most important environmental component establishing boundaries to human activities and its organization on earth surface. Among these activities, agriculture play an important role producing food and to guarantee the commerce of exceeding production among nations. In the international market Brazil is considered as the bigger world-wide soybean producer, with the internal participation led by Mato Grosso, Paraná, and Rio Grande do Sul states. The hypothesis of our work suggests that the different climatic conditions in the Brazilian territory has benefited the migration from the major production regions, until then concentrated in the South Region, to the Center-West region. This migration caused environmental impacts and enhanced social inequalities. In the development of our study this statement was proved when the conditions of the agrarian distribution and the production was analyzed, characterizing low rain variability in Mato Grosso state, as well as the regimen and rainfall distribution, by geoprocessing techniques and the development of an analysis and consultation system based on the resources of navigation through the world wide web, available at http://www.ivanrdea.pop.com.br.
Doutor

APA, Harvard, Vancouver, ISO, and other styles

21

Angelotti, Robert W. "Contaminant removal from impervious pavements and its relationship with raindrop impact energy, cumulative kinetic energy of rainfall events, and rainwater pH." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/90904.

Full text

Abstract:

The relationships between contaminant removal from impervious pavements and raindrop impact energy, cumulative kinetic energy of rainfall events, and rainwater fit were evaluated. A commercial urban area was chosen to perform simulated rainfall experiments. The runoff from these experiments was collected and analyzed for total suspended solids, volatile suspended solids, total Kjeldahl nitrogen, soluble Kjeldahl nitrogen, oxidized nitrogen, ammonia, ortho-phosphate, total phosphorus, soluble phosphorus, total lead and total zinc. Raindrop impact energy, rainfall intensity, rainfall duration, and rainwater pH were factors which were varied to examine their effect on contaminant wash-off phenomena. The present exponential decay theory of contaminant removal was verified and modified to incorporate the cumulative kinetic energy of rainfall events. An empirical model for contaminant removal was also developed. Data showed that both raindrop impact energy and cumulative storm energy had significant effects on contaminant removal. Contaminant wash-off was found to be independent of rainwater pH except for solids removal at low rain intensities. Additional results indicated that there is a "threshold impact energy" necessary before significant removal of contaminants associated with insoluble material can occur. The kinetic energy attributed to surface runoff overflow was found to be very important in the mechanisms responsible for contaminant removal at high rainfall intensities.
M.S.

APA, Harvard, Vancouver, ISO, and other styles

22

Mahbub, S. M. Parvez Bin. "Impact of urban traffic and climate change on water quality from road runoff." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/47139/1/Parvez_Mahbub_Thesis.pdf.

Full text

Abstract:

Urban traffic and climate change are two phenomena that have the potential to degrade urban water quality by influencing the build-up and wash-off of pollutants, respectively. However, limited knowledge has made it difficult to establish any link between pollutant buildup and wash-off under such dynamic conditions. In order to safeguard urban water quality, adaptive water quality mitigation measures are required. In this research, pollutant build-up and wash-off have been investigated from a dynamic point of view which incorporated the impacts of changed urban traffic as well as changes in the rainfall characteristics induced by climate change. The study has developed a dynamic object classification system and thereby, conceptualised the study of pollutant build-up and wash-off under future changes in urban traffic and rainfall characteristics. This study has also characterised the buildup and wash-off processes of traffic generated heavy metals, volatile, semi-volatile and non-volatile hydrocarbons under dynamic conditions which enables the development of adaptive mitigation measures for water quality. Additionally, predictive frameworks for the build-up and wash-off of some pollutants have also been developed.

APA, Harvard, Vancouver, ISO, and other styles

23

Tusher, Md Didarul Alam. "Impact of Extreme Rainfall Event over Swedish Urban Catchments : A study on catchment characterization in the context of Aerial Reduction Factor and storm movement." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-266469.

Full text

Abstract:

The design practices of urban hydraulic structures are required to be based on enough safety measures in addition to cost efficiency for sustainable development. Overestimation of catchment runoff generated from a storm event can increase the project cost unnecessarily. For urban pluvial studies, use of Aerial Reduction Factor (ARF) helps to estimate the probable precipitation intensity inside a catchment. By understanding the necessity of using ARF from a national context and applying it in present design practices can pave the way towards sustainable design practices. In this study the applicability of ARF from Swedish urban context was analyzed. The urban catchments for fifty biggest Swedish cities were delineated and the catchment parameters were analyzed. Application of ARF depends on the size of catchment. To experience a significant reduction in catchment outlet discharge, the minimum catchment area for application of ARF was reported as 5 km2. According to the analyzed parameters, ninety percent of catchment sizes in Swedish urban area were found less than 5 km2, which are quite small in respect of ARF applicability. It was realized from the analysis that application of ARF within a single catchment is not much necessary for pluvial studies in Swedish urban catchments due to catchment properties. In addition to rainfall intensity, rainfall movement also changes the runoff behavior from a catchment. When catchment’s flow velocity and direction through main channel and storm moving velocity and direction over the channel coincides with each other, then the outlet peak discharge magnifies in comparison to a stationery storm, known as resonance effect. The impact of storm movement over catchment was analyzed using HEC-HMS modelling with varying storm movement velocity over catchment. The analysis was performed on 12 catchments of different size and flow velocity. It was found that the peak discharge can increase up to 46 percent depending upon catchment characteristics. The flow velocity through all the delineated catchments of fifty cities were calculated using USDA’s NRCS TR-55 method and then compared with usual storm moving velocities in Sweden. It was found that, due to flat nature of Swedish urban areas, the flow velocities are very low (<2 m/s) in compare to average storm velocity (8 m/s), portraying the fact that there is limited probability that these velocities will coincide. But for any area where storm velocity is normally low, resonance effect can happen. Precise analysis based on local conditions are suggested while modelling a particular area, since impact of resonance effect can overrun the design considerations.

APA, Harvard, Vancouver, ISO, and other styles

24

Costa, Tarcísio Oliveira da. "EVENTOS DE PRECIPITAÇÃO EXTREMA ASSOCIADOS ÀS INUNDAÇÕES NA ÁREA URBANA DE BRAGANÇA/PA." Universidade Federal de Santa Maria, 2014. http://repositorio.ufsm.br/handle/1/9431.

Full text

Abstract:

The study of urban climate has a great importance in regard to the understanding of the human-nature relationship and the interaction between the local climate and the city. This expectation motivated this study on the Urban Climate in the city of Bragança, Pará State, a city that has undergone urban impacts from the rains that cause floods and flooding that hit several areas of the city, especially along the course from the Cereja stream, that is cutting the urban mesh. The Floods are one of the most serious problems which affects the cities when there is an occurrence of extreme precipitation events, generating impacts that affect the daily routine of the people. In this way, the choice for the study of meteoric impact of the channel, the third channel among the subsystems of the Urban Climate System (SCU), it is justified by the study of floods and flooding that happened in the city and the need to understanding the environmental conditions that originate. In this context, this study aimed to analyze the urban climate and extreme expectation events associated with the occurrence of floods and flooding in the urban area of Bragança. Therewith, we analyzed the occurrence of floods in Cereja stream and flooding in Bragança in 2004-2013 period; It was analyzed the variability of precipitation in urban areas from January to May, in 2014; we identified the atmospheric systems linked to extreme expectation events in the urban area of the city; however, the balance of participation of climate systems during the Amazon winter 2014 and it was made a map of climate risk in areas of extreme rainfall situations with sight to urban land use planning in the city. Therefore, the research was based on the SCU theory developed by Monteiro (1976). In the historic flood (2004-2013) were found 32 extreme events, that only 07 were classified as episodes of relevance for this study due to the impact of records in the urban area. The weather data analyzed was collected of the Weather Station Conventional of Tracuateua city (EMT) and Automatic Weather Station of Bragança (EMB) that belongs to INMET and a network of 07 rain gauges installed in the urban area of the city in 2014 which allowed a development of variability maps precipitation during the Amazon winter. Were also it was developed participation swing charts of atmospheric systems with satellite images from GOES 13 aid provided by INPE and Letters daily Synoptic of 00h and 12h provided by the Navy of Brazil. With the results, it was observed that the ZCIT has increased the participation in the occurrence of extreme events and urban impacts, and it was noted that there is a great variability of expectation in the study of the area, up to 161 mm between the northnortheast sector (Rainier) and the South-southwest sector (less rain). Finally we prepared a risk map as a tool for urban land in use planning, considering the local climate variable.
O estudo do clima urbano é de grande importância no que se refere à compreensão da relação homem-natureza e da interação entre o clima local e a cidade. Essa perspectiva motivou este estudo sobre o Clima Urbano de Bragança/PA, cidade que tem sofrido impactos urbanos oriundos das chuvas que provocam inundações e alagamentos que atingem diversas áreas da cidade, principalmente, ao longo do curso do Igarapé Cereja, que corta a malha urbana. As inundações são um dos graves problemas que afetam as cidades quando há ocorrência de eventos de precipitação extrema, gerando impactos que influenciam no cotidiano das populações. Nesse sentido, a escolha pelo estudo do canal do Impacto Meteórico, terceiro canal dentre os subsistemas do Sistema Clima Urbano (SCU), justifica-se pelo estudo das inundações e alagamentos que tem ocorrido em Bragança e pela necessidade de entendimento das condições climáticas que as originam. Nesse contexto, este trabalho teve como objetivo geral analisar o clima urbano e os eventos de precipitação extrema associados à ocorrência de inundações e alagamentos na área urbana de Bragança-PA. Com isso, analisou-se a ocorrência de inundações no Igarapé Cereja e alagamentos em Bragança no período de 2004-2013; analisou-se a variabilidade da precipitação na área urbana no período de janeiro à maio do ano de 2014; identificou-se os sistemas atmosféricos ligados aos eventos de precipitação extrema na área urbana de Bragança-PA; realizou-se o balanço de participação dos sistemas atmosféricos durante o inverno amazônico de 2014 e elaborou-se um mapa de áreas de risco climático em situações de extrema precipitação com vistas ao ordenamento territorial urbano do município. Para tanto, a pesquisa baseou-se na teoria do SCU elaborada por Monteiro (1976). No histórico de inundações (2004-2013) foram encontrados 32 eventos extremos, dos quais apenas 07 foram classificados como episódios de relevância para este estudo, devido aos registros de repercussão na área urbana. Os dados meteorológicos analisados foram coletados da Estação Meteorológica Convencional de Tracuateua (EMT) e Estação Meteorológica Automática de Bragança (EMB), pertencente ao INMET e por uma rede de 07 pluviômetros instalados na área urbana de Bragança/PA em 2014, que possibilitou elaboração de mapas da variabilidade da precipitação durante o inverno amazônico. Foram também elaborados gráficos de balanço de participação mensal dos sistemas atmosféricos, com auxílio de imagens do satélite GOES 13 disponibilizadas pelo INPE e Cartas Sinóticas diárias das 00h e 12h disponibilizadas pela Marinha do Brasil. Com os resultados, observou-se que a ZCIT tem maior participação na ocorrência de eventos extremos e impactos urbanos, além de observar-se que há uma grande variabilidade da precipitação na área de estudo, de até 161 mm entre o setor norte-nordeste (mais chuvoso) e o setor Sul-sudoeste (menos chuvoso). Por fim foi elaborado um mapa de riscos como instrumento para o ordenamento territorial urbano, considerando a variável climática local.

APA, Harvard, Vancouver, ISO, and other styles

25

Keba, Habtamu Teka. "The impact of changes in land-use patterns and rainfall variability on range condition and pastoral livelihoods in the Borana rangelands of southern Oromia, Ethiopia." Thesis, University of Pretoria, 2013. http://hdl.handle.net/2263/32981.

Full text

Abstract:

This study was conducted in the Borana rangelands, southern Oromia, Ethiopia with the aim of investigating land-use/cover changes, rangeland condition and indentifying major change drivers in the rangelands. Satellite image scenes, ground survey and people’s perceptions were assessed to identify changes on herbaceous and woody species composition. Ordination techniques were used for correlation of grass and woody species into environmental variables. Piospheric effects on vegetation composition around patch resources were also examined. These assessments were designed to bring out both spatial and seasonal variation in vegetation parameters. Rangeland condition was determined using the ecological index (EIM) and the weighted palatability composition (WPC) methods. Grazing capacity assessment was largely based on rain-use efficiency, range condition, density of woody plants. Woody cover in the Borana increased from 11.3% in the 1970s to 49.26% in 2000s, while, grassland cover declined from 58% to 32% during the same period. The cultivated/built up area also increased gradually over the years though the extent of increment was less compared to the woody cover changes. The calculated NDVI values for the 2000s were low relative to the 1970s. Ground survey results demonstrated that herbaceous biomass production and woody plant density varied significantly (P < 0.01) for the different sites in Borana. Nevertheless, herbaceous plant diversity and evenness did not differ significantly (P>0.05) across the different sites and around patch resource areas. This confirms the resilience of the Borana rangeland to the effects of grazing pressure and climatic variability. Overall, the density of woody plants varied from moderate to sever encroachment, which corresponds to the rangeland condition classes from very poor to fair. The results of the present study showed that the nutrient contents of herbaceous plants (CP, NDF, ADF, ADL and ash) were greatly influenced by species, stage of maturity, site and season. Herbaceous species with high crude protein content based on laboratory results were also ranked as the top important species by the pastoralists. Similarly, herbaceous forage species with a high structural fiber were considered inferior. Pastoralists’ knowledge and laboratory results on the nutritive value of key herbaceous species complemented each other. The stocking density of livestock units was higher than the grazing capacity for the Borana rangelands. Stocking density for the Borana rangeland using rain-use efficiency was 1.43 ha/TLU. There was no significant difference in the grazing capacity across the different sites in the study area under the existing management. The majority of pastoralists believed that the rangelands in Borana have been degraded, as consequence of recurrent drought (83%), population pressure (65%), poor management and inappropriate government policy (38%). The majority of the respondents (94%) also asserted that the traditional coping mechanisms of Borana pastoralists have declined. There is therefore a need for designing appropriate pastoral land-use policies that fit the ecological potential of the region to ensure sustainable ecosystem functioning. We suggest a comprehensive and adaptive range management for the implementation of appropriate land-use systems for the different livestock species. There is need to adjust stocking rates based on seasonal availability of forage. This would foster economic feasibility and ecological sustainability of the Borana pastoral production system.
Thesis (PhD)--University of Pretoria, 2013.
gm2013
Plant Production and Soil Science
Unrestricted

APA, Harvard, Vancouver, ISO, and other styles

26

Castellano, Marina Sória 1984. "Inundações em Campinas (SP) entre 1958 e 2007 = tendências sócioespaciais e as ações do poder público." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/286907.

Full text

Abstract:

Orientador: Lucí Hidalgo Nunes
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
Made available in DSpace on 2018-08-17T09:45:14Z (GMT). No. of bitstreams: 1 Castellano_MarinaSoria_M.pdf: 4550077 bytes, checksum: f0be7cc7ab35dc3a5dd1ff60bfd85e2e (MD5) Previous issue date: 2010
Resumo: Totalizando um terço de todos os desastres naturais mundiais (SMITH, 2004), as inundações são eventos naturais, podendo ter suas consequências agravadas por ações antrópicas, como a urbanização, falta de planejamento urbano e ocupações de áreas de risco. Essa é a realidade de grande parte dos centros urbanos do Brasil, onde se inclui a cidade de Campinas (SP). A pesquisa teve como objetivo analisar, para esse município, os impactos relacionados às chuvas extremas entre 1958 e 2007, avaliando o padrão sócioespacial nas suas distribuições. Foram utilizados quatro postos pluviométricos para o levantamento dos episódios extremos, identificados de acordo com a técnica dos quantis. A partir da delimitação desses dias, os impactos associados às chuvas foram levantados nos jornais Correio Popular, Diário do Povo (jornais locais), O Estado de São Paulo, Folha de São Paulo e na Defesa Civil do município. As informações foram analisadas de acordo com 5 décadas e percebeu-se um aumento considerável na quantidade de impactos registrados: foram 129 na primeira década e 3837 na última. A análise dos dados também permitiu perceber que os bairros de baixa e média renda são maioria em grande parte dos registros. Dos 34 tipos de impactos registrados, 16 ocorreram com mais frequência em áreas de baixa renda (destacando-se os casos de alagamento e risco de desabamento de imóveis, desabrigados e mortos), 15 em áreas de renda média (destacando-se alagamento de vias e desabamento total ou parcial de imóveis) e 2 em áreas de alta renda (atraso em obras e danos em imóveis). Assim, percebe-se que os fenômenos extremos afetam mais rotineiramente e de maneira mais dramática os grupos sociais menos favorecidos. Porém, bairros de todos os extratos sociais foram afetados, mostrando que praticamente toda a população está exposta a risco, ainda que de diferentes magnitudes, o que se coloca como um aspecto relevante para o poder público. A pesquisa também contou com a análise dos Planos Diretores e de Gestão Urbana de Campinas, assim como programas executados pela Prefeitura que visam a diminuição das inundações no município. Nota-se que grande parte dos pontos abordados nesses documentos oficiais como áreas críticas de inundação eram compatíveis com os locais levantados em jornais e na Defesa Civil. As questões climáticas não foram abordadas nos planos de maneira direta: apenas há a ideia implícita da ocorrência de chuvas (não havendo menção às suas intensidades), quando há a referência às inundações. Os assuntos relacionados às inundações e que aparecem com frequência nos planos analisados são: áreas verdes, impermeabilização do solo, ocupação de áreas de risco, remoção e reassentamento de famílias e política habitacional
Abstract: Floods are natural events but they correspond to a third of all natural disasters worldwide (Smith, 2004) and their consequences can be aggravated by human activities, such as urbanization, lack of urban planning and occupation of risk areas. These facts occur on most urban centers in Brazil, including the city of Campinas (SP). The research aimed to analyze the impacts of extreme precipitation events between 1958 and 2007 for Campinas and to estimate the socio-spatial pattern of their distributions. Data of four rain gauges were used for the analysis of extreme events identified according to the quantis technique. The impacts associated with the rains were reported in the newspaper Correio Popular, Diário do Povo (local newspapers), O Estado de São Paulo as well the Civil Defense. Analyses were performed for five decades and showed a considerable increase in the number of impacts recorded: 129 in the first decade and 3,837 in the last. The data analysis also allowed to realize that the areas of low and medium income are the majority in most of the records. Of the total impacts, 16 occurred more frequently in low-income areas (with emphasis on cases of flooding and risk of collapse of buildings, homeless and dead), 15 in middle income areas (in particular, flooding of roads and total or partial collapse of buildings) and 2 in high-income (under construction delays and damage to properties). Thus, it was noticed that the extreme phenomena affect more routinely and dramatically low income social groupings. However, the neighborhoods of all social classes were affected, showing that the entire population is exposed to risk, although in different magnitudes, which is a relevant aspect for the government. The research also included the analysis of Master Plans of Campinas, as well as executed programs by the local government to reduce flooding in the city. It was noticed that most of the places presented as critical areas to flooding in the official documents were compatible with the areas that really presented problems, according to the survey in local newspapers and on Civil Defense. Climate issues were not reported in the plans in a direct way: there is only the implicit idea of the rainfall occurrence (there was no mention of their intensities) when there is a reference to flooding. The issues related to flooding that appear with frequency in the plans analyzed are: green areas, soil impermeabilization, risk areas occupation, transference of families and resettlement and housing policy
Mestrado
Análise Ambiental e Dinâmica Territorial
Mestre em Geografia

APA, Harvard, Vancouver, ISO, and other styles

27

Janse, van Rensburg Unique. "Quantification of potential elemental impact of a munitions production and testing facility on its immediate surroundings / Unique Janse van Rensburg." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4575.

Full text

Abstract:

The study attempted to quantify the elemental concentrations and possible accumulation levels in the antelope's organ tissue at Rheinmetal Denel Munitions (RDM), as well as to correlate the findings with the surrounding environment. To achieve this, the elemental concentrations within the kidney, liver and lung tissue of the antelope, and environmental factors such as the soil, vegetation and waterholes were quantified. STATISTICA was used to determine meaningful differences between variables and Canoco to determine the relationship between the different datasets. PCA analyses of the vegetation confirmed that the natural slope at RDM could have contributed to the distribution and variation of the elemental concentration. It became apparent that positive associations existed between the liver tissue and the K, the kidney tissue and Ni and Cd, and the lung tissue had a positive association with Mg, Mn, V, Rb and Co elemental concentrations. It became evident in this study that the elemental concentrations of Al and Ni were higher in the liver and kidney tissue of the antelope than the recommended concentration for livestock (Puls, 1994). The elemental concentration of Al, Ca, Fe and Mn also exceeded the recommended elemental concentration for livestock, in the water sampled at RDM (Puls, 1994). Four distinct areas were identified within the study area, the area above the factory, the area under the factory, the testing area and the area under the factory. Significant differences between the testing area and the area under the factory were found regarding the Tl, Ag, Hg and B elemental concentrations in the vegetation. Furthermore, it became apparent that the amount of precipitation could have contributed to the variation of the elemental concentrations and distribution in the study area as well as in the organ tissue of the antelope.
Thesis (M.Sc. (Environmental Science and Management))--North-West University, Potchefstroom Campus, 2011.

APA, Harvard, Vancouver, ISO, and other styles

28

Navas, Nunez Rafael. "Modélisation hydrologique distribuée des crues en région Cévennes-Vivarais : impact des incertitudes liées à l'estimation des précipitations et à la paramétrisation du modèle." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAU025/document.

Full text

Abstract:

Il est connu qu’avoir un système d’observation de la pluie de haute résolution spatio – temporelle est crucial pour obtenir de bons résultats dans la modélisation pluie – écoulement. Le radar est un outil qui donne des estimations quantitatives de precipitation avec une très bonne résolution. Lorsqu’il est fusionné avec un réseau des pluviomètres les avantages des deux systèmes sont obtenus. Cependant, les estimations fournies par le radar ont des incertitudes différentes à celles qui sont obtenus avec les pluviomètres. Dans le processus de calcul pluie – écoulement l'incertitude des précipitations interagit avec l'incertitude du modèle hydrologique. L’objectif de ce travail est d’étudier les méthodes utilisées pour quantifier l'incertitude dans l'estimation des précipitations par fusion radar – pluviomètres et de l'incertitude dans la modélisation hydrologique, afin de développer une méthodologie d'analyse de leurs contributions individuelles au traitement pluie - écoulement.Le travail est divisé en deux parties, la première cherche à évaluer: Comment peut-on quantifier l'incertitude de l'estimation des précipitations par radar? Pour répondre à la question, l'approche géostatistique par Krigeage avec Dérive Externe (KED) et Génération Stochastique de la précipitation a été utilisée, qui permet de modéliser la structure spatio – temporaire de l’erreur. La méthode a été appliquée dans la région des Cévennes - Vivarais (France), où il y a un système très dense d'observation. La deuxième partie explique: Comment pourrais être quantifiée l'incertitude de la simulation hydrologique qui provient de l'estimation de précipitation par radar et du processus de modélisation hydrologique? Dans ce point, l'outil de calcul hydrologique à Mesoéchelle (HCHM) a été développé, c’est un logiciel hydrologique distribuée et temps continu, basé sur le Numéro de Courbe et l’Hydrographe Unitaire. Il a été appliqué dans 20 résolutions spatio - temporelles allant de 10 à 300 km2 et 1 à 6 heures dans les bassins de l’Ardèche (~ 1971 km2) et le Gardon (1810 km2). Apres une analyse de sensibilité, le modèle a été simplifié avec 4 paramètres et l’incertitude de la chaîne de processus a été analysée: 1) Estimation de precipitation; 2) Modélisation hydrologique; et 3) Traitement pluie - écoulement, par l’utilisation du coefficient de variation de l'écoulement simulé.Il a été montré que KED est une méthode qui fournit l’écart type de l’estimation des précipitations, lequel peut être transformé dans une estimation stochastique de l’erreur locale. Dans la chaîne des processus: 1) L'incertitude dans l'estimation de précipitation augmente avec la réduction de l’échelle spatio – temporelle, et son effet est atténué par la modélisation hydrologique, vraisemblablement par les propriétés de stockage et de transport du bassin ; 2) L'incertitude de la modélisation hydrologique dépend de la simplification des processus hydrologiques et pas de la surface du bassin ; 3) L'incertitude dans le traitement pluie - écoulement est le résultat de la combinaison amplifiée des incertitudes de la précipitation et la modélisation hydrologique
It is known that having a precipitation observation system at high space - time resolution is crucial to obtain good results in rainfall - runoff modeling. Radar is a tool that offers quantitative precipitation estimates with very good resolution. When it is merged with a rain gauge network the advantages of both systems are achieved. However, radars estimates have different uncertainties than those obtained with the rain gauge. In the modeling process, uncertainty of precipitation interacts with uncertainty of the hydrological model. The objective of this work is: To study methods used to quantify the uncertainty in radar – raingauge merge precipitation estimation and uncertainty in hydrological modeling, in order to develop a methodology for the analysis of their individual contributions in the uncertainty of rainfall - runoff estimation.The work is divided in two parts, the first one evaluates: How the uncertainty of radar precipitation estimation can be quantified? To address the question, the geostatistical approach by Kriging with External Drift (KED) and Stochastic Generation of Precipitation was used, which allows to model the spatio - temporal structure of errors. The method was applied in the Cévennes - Vivarais region (France), where there is a very rich observation system. The second part explains: How can it be quantified the uncertainty of the hydrological simulation coming from the radar precipitation estimates and hydrological modeling process? In this point, the hydrological mesoscale computation tool was developed; it is distributed hydrological software in time continuous, within the basis of the Curve Number and the Unit Hydrograph. It was applied in 20 spatio-temporal resolutions ranging from 10 to 300 km2 and 1 to 6 hours in the Ardèche (~ 1971 km2) and the Gardon (1810 km2) basins. After a sensitivity analysis, the model was simplified with 4 parameters and the uncertainty of the chain of process was analyzed: 1) Precipitation estimation; 2) Hydrological modeling; and 3) Rainfall - runoff estimation, by using the coefficient of variation of the simulated flow.It has been shown that KED is a method that provides the standard deviation of the precipitation estimation, which can be transformed into a stochastic estimation of the local error. In the chain of processes: 1) Uncertainty in precipitation estimation increases with decreasing spatio-temporal scale, and its effect is attenuated by hydrological modeling, probably due by storage and transport properties of the basin; 2) The uncertainty of hydrological modeling depends on the simplification of hydrological processes and not on the surface of the basin; 3) Uncertainty in rainfall - runoff treatment is the result of the amplified combination of precipitation and hydrologic modeling uncertainties

APA, Harvard, Vancouver, ISO, and other styles

29

Cassé, Claire. "Impact du forçage pluviométrique sur les inondations du fleuve Niger à Niamey : Etude à partir de données satellitaires et in-situ." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30236/document.

Full text

Abstract:

Depuis le développement des mesures satellites de nombreuses missions spatiales sont dédiées au suivi de l'atmosphère et de la surface terrestre. Ces travaux de thèse s'inscrivent dans le cadre de la mission Megha-Tropiques dédiée au cycle de l'eau et de l'énergie en zone tropicale. L'objectif est d'évaluer le potentiel des estimations de précipitation par satellite pour des applications hydrologiques en zone tropicale. Les Tropiques réunissent les plus grands fleuves du globe, mais ne bénéficient pas de réseaux d'observation in-situ denses et continus permettant une gestion intégrée efficace de la ressource et des systèmes d'alertes. Les estimations des précipitations issues des systèmes d'observation satellite offrent une alternative pour ces bassins peu ou pas instrumentés et souvent exposés aux extrêmes climatiques. C'est le cas du fleuve Niger, qui a subi une grande variabilité climatique depuis les années 1950, mais aussi d'importants changements environnementaux et hydrologiques. Depuis les années 2000, le Niger moyen connaît une recrudescence des inondations pendant la période de crue Rouge (engendrée par ses affluents sahéliens pendant la mousson). A Niamey, des niveaux record de hauteur d'eau et de période d'inondation ont été enregistrés en 2003, 2010, 2012 et 2013, engendrant de nombreuses pertes humaines et matérielles. Ces travaux analysent l'influence du forçage pluviométrique sur les inondations liées à la crue Rouge à Niamey. Une gamme de produits pluviométriques (in situ et satellite) et la modélisation hydrologique (ISBA-TRIP) sont combinés pour étudier : (i) l'apport des produits satellite pour diagnostiquer la crue Rouge récente, (ii) l'impact des caractéristiques des produits et de leurs incertitudes sur les simulations et enfin (iii) l'évaluation du rôle des précipitations, face aux changements de conditions de surface, dans l'évolution de la crue Rouge à Niamey depuis les années 1950. L'étude a mis en évidence l'impact des caractéristiques des estimations des précipitations (cumul, intensité et distribution spatio-temporelle) sur la modélisation hydrologique et le potentiel des produits satellites pour le suivi des inondations. Les caractéristiques des précipitations se propageant dans la modélisation, la détection des inondations est plus efficace avec une approche relative à chaque produit plutôt qu'avec un seuil absolu. Ainsi des produits présentant des biais peuvent être envisagés pour la simulation hydrologique et la détection des inondations. Le nouveau produit TAPEER de la mission MT présente un fort potentiel hydrologique, en 2012 et pour la zone d'étude. D'autre part, l'étude de la propagation de l'erreur associée à ces précipitations a mis en évidence, la nécessité de déterminer la structure du champ d'erreur pour l'utilisation d'une telle information en hydrologie. Enfin la modélisation a été utilisée comme levier pour décomposer les sensibilités de la crue Rouge aux variations des précipitations et des conditions de surface. Pour simuler les changements hydrologiques entre les périodes 1953-1982 et 1983-2012, les changements d'occupation du sol et d'aire de drainage doivent être pris en compte. Puis les variations des précipitations peuvent expliquer les changements majeurs décennaux et annuels entre les années 1983 et 2012
Since the development of satellite based remote sensing in the 1970s, many missions have been dedicated to monitoring the terrestrial atmosphere and surfaces. Some of these satellites are dedicated to the Tropics with specific orbits. Megha-Tropiques (MT) is devoted to the water and energy cycle in the tropical atmosphere and provides an enhanced sampling for rainfall estimation in the tropical region. This PhD work was initiated within MT hydro-meteorological activities, with the objective of assessing the hydrological potential of satellite rainfall products in the Tropics. The world most important rivers lay in tropical areas where the in situ observation networks are deficient. Alternative information is therefore needed for water resource management and alert systems. The present work focuses on the Niger River a basin which has undergone drastic climatic variations leading to disasters such as droughts and floods. Since 1950, the Niger has been through 3 main climatic periods: a wet period (1950-1960), a long and intense drought period (1970-1980) and since 1990 a partial recovery of the rainfall. These climatic variations and the anthropic pressure, have modified the hydrological behaviour of the basin. Since 2000, the middle Niger River has been hit by an increase of floods hazards during the so-called Red flood period. In Niamey city, the highest river levels and the longest flooded period were recorded in 2003, 2010, 2012 and 2013, leading to heavy casualties and property damage. This study combines hydrological modelling and a variety of rainfall estimation products (satellite and in-situ) to meet several objectives: (i) the simulation of the Niamey Red flood and the detection of floods (during the recent period 2000-2013) (ii) the study of the propagation of satellite rainfall errors in hydrological modelling (iii) the evaluation of the role of rainfall variability, and surface conditions, in the changes of the Red flood in Niamey since the 50s. The global model ISBA-TRIP, is run with a resolution of 0.5° and 3h, and several rainfall products were used as forcing. Products derived from gauges (KRIG, CPC), pure satellite products (TAPEER, 3B42RT, CMORPH, PERSIANN) and mixed satellite products adjusted by rain gauges (3B42v7, RFE2, PERSIANN-CDR). This work confirms the hydrological potential of satellite rainfall products and proposes an original approach to overcome their biases. It highlights the need for documenting the errors associated with the rainfall products and the error structure. Finally, the hydrological modelling results since the 1950s have given a new understanding of the relative role of rainfall and surface conditions in the drastic increase of flood risk in Niamey

APA, Harvard, Vancouver, ISO, and other styles

30

Fonseca, Rogério Gerolineto [UNESP]. "Risco hidrológico: precipitações extremas, enchentes e alagamentos na cidade de Ituiutaba (MG)." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/152414.

Full text

Abstract:

Submitted by ROGÉRIO GEROLINETO FONSECA null (rogeriogfonseca@yahoo.com.br) on 2018-01-03T14:27:02Z No. of bitstreams: 1 RISCO_HIDROLOGICO_PRECIPITACOES_EXTREMAS_ENCHENTES_E_ALAGAMENTOS_NA_CIDADE_DE_ITUIUTABA_MG.pdf: 10330534 bytes, checksum: b95ceb5e240dacedaa2b614729085529 (MD5)
Approved for entry into archive by Adriana Aparecida Puerta null (dripuerta@rc.unesp.br) on 2018-01-05T10:43:37Z (GMT) No. of bitstreams: 1 fonseca_rg_me_rcla.pdf: 9246593 bytes, checksum: cbd5879270cf75f0e834161707e18c48 (MD5)
Made available in DSpace on 2018-01-05T10:43:37Z (GMT). No. of bitstreams: 1 fonseca_rg_me_rcla.pdf: 9246593 bytes, checksum: cbd5879270cf75f0e834161707e18c48 (MD5) Previous issue date: 2017-11-10
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
As inundações constituem um dos impactos ambientais mais observados nas áreas urbanas. A incidência destes eventos varia conforme as características climáticas e socioambientais das cidades. Esta pesquisa teve como objetivo principal avaliar o risco a enchentes, a alagamentos e ao escoamento superficial concentrado na área urbana de Ituiutaba (MG), a partir de suas condicionantes físicas e de suas características socioespaciais, inerentes ao processo de urbanização. Para isto, realizaram-se análises do geossistema urbano; da variabilidade pluvial com enfoque na recorrência das precipitações extremas; das ocorrências de transtornos associados ao impacto pluvial e da percepção do problema por parte da população atingida e do poder público municipal. Verificou-se que os impactos hidrometeóricos concentram-se durante os meses da primavera e do verão, quando as chuvas são mais abundantes. Em média, treze episódios chuvosos com volume a partir de 30mm/24h acontecem a cada ano, representando, assim, um potencial de danos ao ambiente urbano. De forma mais esporádica, acontecem ainda precipitações mais intensas, por volta de 90mm/24h, com potencial de impacto muito maior. Os arquivos das ocorrências do Corpo de Bombeiros e as reportagens publicadas pela imprensa local constituíram importantes fontes para o mapeamento e análise dos impactos. Como consequência desses eventos, tem-se na área central da cidade e bairros adjacentes, que são mais impermeabilizados, as ocorrências de escoamento superficial concentrado e os alagamentos. Além disso, a rede de galerias pluviais é insuficiente para drenar os locais onde os problemas são mais evidentes, principalmente em quatro áreas, sendo estas as avenidas José João Dib, Minas Gerais, Dezessete e Prof. José Vieira de Mendonça. Na primeira, observam-se alagamentos devido à deficiência na drenagem do escoamento superficial, que não consegue direcionar as águas para dentro da canalização do Córrego São José. Nos demais locais o problema é o escoamento superficial concentrado, que forma um fluxo ao longo das vertentes, suficiente para arrastar pessoas e veículos, além de provocar danos na pavimentação de ruas e calçadas. No tocante à população afetada pelas inundações, a maior parcela é formada por pessoas de baixa renda, cujas residências são mais vulneráveis ao acúmulo/escoamento de água em superfície. Este cenário demanda a atuação efetiva da administração pública no sentido de elaborar planos estratégicos para a gestão das águas pluviais.
Floods are one of the most observed environmental impacts in urban areas. The incidence of these events varies according to the climatic and socio-environmental characteristics of the cities. The main objective of this research was to evaluate the risk to the overflows, the floods and the concentrated surface runoff in the urban area of Ituiutaba (MG), based on its physical conditioning aspects and its socio-spatial characteristic, which are inherent in the urbanization process. For that purpose, some analyzes of the urban geosystem, the rainfall variability with focus on the recurrence of the extreme precipitations, the occurrences of disturbances associated with the rainfall impact and the perception of the problem by the affected population and the municipal public power were carried out. It was found that the hydrometeoric impacts are concentrated in the spring and summer months, when the rains are more abundant. On average, thirteen rainy episodes with a volume from 30mm/24h happen each year, which represents a potential for damages to the urban environment. More sporadically, there are some intense precipitations, around 90mm/24h, with a much greater potential impact. The Fire Department's archives and the news published in the local press were important sources for the mapping and analysis of the impacts. As a consequence of these events, there are in the city centre area and adjacent neighborhoods, which are more waterproofed spaces, the occurrences of concentrated surface runoff and flooding. In addition, the rain gutter network is insufficient to drain the places where the problems are more evident, mainly in four areas, which are the avenues José João Dib, Minas Gerais, Dezessete and Prof. José Vieira de Mendonça. At the José João Dib Avenue, floods are observed due to the deficiency in drainage of the surface runoff, that cannot direct the water into the canalization of the São José stream. In the other avenues, the problem is the concentrated runoff which forms a flow along the slopes that is enough to drag people and vehicles as well as cause damage to the paving of streets and sidewalks. With regard to the population affected by the floods, the majority is made up of low-income people, whose homes are most vulnerable to surface water accumulation / runoff. This scenario demands an effective action from the public administration in an effort to elaborate strategic plans for the management of the rainwater.
CNPq: 134118/2015-4

APA, Harvard, Vancouver, ISO, and other styles

31

Coustau, Mathieu. "Contribution à la prévision des crues sur le bassin du Lez : modélisation de la relation pluie-débit en zone karstique et impact de l'assimilation de débits." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20229/document.

Full text

Abstract:

Les crues « éclair » parfois dévastatrices qui touchent les bassins versants méditerranéens du Sud de la France sont difficiles à anticiper. Leur prévision passe par l'utilisation de modèles pluie-débit, dont l'efficacité est encore limitée par les incertitudes liées notamment à la variabilité spatiale des pluies méditerranéennes et à la caractérisation de l'état hydrique initial des hydrosystèmes. Dans le cas de bassins karstiques, à ces incertitudes s'ajoutent celles liées à la dynamique des aquifères et à leur rôle sur la formation des crues. La première partie de ce travail de thèse propose un modèle pluie-débit horaire, distribué, événementiel et parcimonieux pour reproduire les crues « éclair » à l'exutoire du bassin karstique du Lez (Montpellier) de 114 km2. Le modèle est évalué non seulement sur la qualité des simulations de débits mais aussi sur la qualité de son initialisation obtenu grâce à une relation entre sa condition initiale et divers indicateurs de l'état hydrique de l'hydrosystème. Calibré sur 21 épisodes de crues, le modèle fournit des simulations satisfaisantes, et sa condition initiale est significativement corrélée à l'indice d'humidité Hu2 du modèle SIM de Météo-France ou à la piézométrie dans l'aquifère du Lez. Les pluies mesurées par radar en début d'automne sont de bonne qualité et conduisent à une amélioration des simulations de débit et de l'estimation de la condition initiale du modèle. En revanche, les pluies mesurées par radar en fin d'automne sont de moindre qualité et n'améliorent pas les simulations. Face aux incertitudes liées à la paramétrisation du modèle ou à l'estimation des pluies radar, la deuxième partie du travail de thèse analyse l'apport de l'assimilation des débits observés pour corriger en temps réel les paramètres les plus sensibles du modèle et notamment sa condition initiale ou les pluies radar en entrée du modèle. La procédure d'assimilation de données a été mise en place à l'aide du coupleur PALM, qui permet de relier modèle hydrologique à l'algorithme d'assimilation. La correction de la condition initiale du modèle permet généralement d'améliorer les prévisions (sous hypothèse de pluie future connue); la correction de la pluie a des effets similaires. Néanmoins les limites de cette correction sont atteintes dans le cas où le modèle ne reproduit pas de façon satisfaisante la partie initiale de montée des eaux, ce qui pourra être amélioré par la suite. Finalement, ce travail de thèse montre que la complexité d'un bassin karstique peut être représentée efficacement à l'aide d'un nombre réduit de paramètres, pour simuler les débits, et contribue à l'amélioration des outils opérationnels pour la prévision des crues
The sometimes devastating flash floods which affect the Mediterranean watersheds of the South of France are difficult to anticipate. Flood forecasting requires the use of rainfall-runoff models which are limited in their efficiency by uncertainty related to the spatial variability of Mediterranean rainfall and the characterization of the initial hydric state of the system. In karstic catchments, these uncertainties are added to those due to aquifer dynamics and their role in flood genesis. The first part of this work will present a distributed event-based parsimonious hourly rainfall-runoff model in order to reconstruct flash flood events at the outlet of the 114 km2 Lez Catchment (Montpellier). The model is evaluated not only for the quality of the simulations produced, but for the quality of its parameter initialization obtained using a relationship between the initial condition and various hydric state indicators of the system. Calibrated using 21 flood episodes, the model produces satisfactory simulations and its initial condition is significantly correlated with the Hu2 soil humidity index of the Météo-France model or piezometers measuring the Lez aquifer. Radar rainfall data measured in early fall are of good quality and lead to improved discharge simulations and an improved estimation of the model initial condition. However, rainfall measured by radar in late fall are of poor quality and do not improve the simulations. Confronted with the uncertainty related to model parametrization or the estimation of radar rainfall, the second part of this dissertation analyzes improvements achieved by assimilating observed discharge measurements in order to perform real-time corrections to the most sensitive model parameters and notably the initial condition and the radar rainfall input to the model. The data assimilation procedure was implemented with the help of the PALM coupling software which allows for the linking of the hydrological model with the assimilation algorithm. Correcting the initial condition allowed for, on average, the improvement of forecasting (under a known future rainfall hypothesis); correcting the rainfall had similar effects. Nevertheless, the limits of this approach are reached when the model is unable to satisfactorily reproduce the rising limb of the hydrograph, a problem which may be addressed by future research. Finally, this body of work demonstrates that the complexity of a karstic catchment can be efficiently represented with a reduced number of parameters in order to simulate discharges and contribute to the improvement of operational tools for flood forecasting

APA, Harvard, Vancouver, ISO, and other styles

32

Alsarawi, Noura. "Design of Low Impact Development and Green Infrastructure at Flood Prone Areas in the City of Miami Beach, FLORIDA, USA." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3739.

Full text

Abstract:

This thesis investigates the effectiveness of Low Impact Development Infrastructure (LIDI) and Green Infrastructure (GI) in reducing flooding resulting from heavy rainfall events and sea-level rise, and in improving stormwater quality in the City of Miami Beach (CMB). InfoSWMM was used to simulate the 5, 10, and 100-year, 24-hour storm events, total suspended solids (TSS), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) loadings, and in evaluating the potential of selected LIDI and GI solutions in North Shore neighborhood. Post-development results revealed a decrease of 48%, 46%, and 39% in runoff, a decrease of 57%, 60%, and 62% in TSS, a decrease of 82%, 82%, and 84% in BOD, and a decrease of 69%, 69%, and 70% in COD loadings. SWMM 5.1 was also used to simulate the king tide effect in a cross section in Indian Creek Drive. The proposed design simulations successfully demonstrated the potential to control flooding, showing that innovative technologies offer the city opportunities to cope with climate impacts. This study should be most helpful to the CMB to support its management of flooding under any adaptation scenarios that may possibly result from climate changes. Flooding could be again caused as a result of changes in inland flooding from precipitation patterns or from sea-level rise or both.

APA, Harvard, Vancouver, ISO, and other styles

33

Zahabiyoun, Bagher. "Stochastic generation of daily streamflow data incorporating land use and/or climate change effects." Thesis, University of Newcastle Upon Tyne, 1999. http://hdl.handle.net/10443/733.

Full text

Abstract:

In the stochastic hydrology literature, suitable time series modelling approaches have been developed for modelling daily streamflow. However, problems arise with this approach if changes are occurring to the precipitation regime generating the historic streamflow data, or if land-use changes are occurring within the catchment which may alter the water balance and the streamflow regime. Traditional time series modelling approaches employ historic streamflow data only and will generate synthetic data which are representative only of the historic conditions. It is not possible to predict how the model parameters should be changed to reflect changes in the climate (precipitation) and catchment response regimes. Developing a methodology to deal with the stochastic generation of daily streamflow that reflects changes to the catchment system and climatic inputs (rainfall and potential evapotranspiration) and then applying the corresponding methodology to a study catchment (upper Thames) in England is the focus of this study. To study the water resources impacts of land-use change on the daily streamflow regime of a catchment, a daily rainfall-runoff model is needed which can accommodate various land cover characteristics and provide separate estimates of potential and actual evapotranspiration in its evapotranspiration component for each land cover type. Given a model with this capability, the impacts of various land-use scenarios on daily streamflow can be investigated. In the case of climate change, since GCMs do not provide useable results on a short time scale such as a day and on a spatial scale such as a catchment of about 1000 km2, a methodology is required to predict the changes which may occur in the climate inputs of a catchment, and the resulting impacts on water resources. The approach developed here for water resources impact studies of land-use change and climate change has three main elements: (I) Two stochastic models, one for rainfall (Neyman-Scott Rectangular Pulses, NSRP, model) and the other for potential evapotranspiration (PET), are employed to generate daily rainfall and daily PET sequencesr,e spectively. Thesem odels have been validated using historic records for the study catchment. ABSTRACT ii (II) The ARNO model has been calibrated and validated using daily streamflow data for the study catchment. The evapotranspiration component of the model has been modified to obtain a satisfactory water balance. The model is then extended to include the explicit calculation of interception for different land cover types within the catchment. The runoff from these areas is then routed to the catchment outlet. The rainfall and PET models are used to generate synthetic daily input series to the modified ARNO model for present catchment land-use conditions, and overall procedure is validated using the historic streamflow record. This is then worked out using the extended model and referred to as the constructed` control' scenariow hich is used as a benchmarkf or assessingla nd-usec hange impacts on water resources for two different land-use scenarios. (III) The transient GCM climate scenarios are used as the starting point for assessing climate change impacts. Regression relationships are derived between atmospheric circulation variables and rainfall statistics used in fitting the NSRP model for present climate conditions and then used to predict the rainfall statistics for future conditions using GCM outputs. That is, the scenarios of a climate model are downscaled by a regression technique to a resolution sufficient to represent daily rainfall at the catchment scale. To generate potential evapotranspiration (PET) scenarios, an empirical equation is used to estimate PET daily values as a function of temperature, thus enabling future scenarios to be generated as a function of GCM temperature predictions. Generated rainfall and PET scenarios are used as inputs to the adapted ARNO catchment response model to generate daily streamflow data. Impact assessments using both land-use change and climate change scenarios are then carried out using a range of water resources assessment measures such as flow duration curves, cumulative run sums and storage/yield relationships, and the practical implications discussed.

APA, Harvard, Vancouver, ISO, and other styles

34

McMahan, Erin K. "Impacts of rainfall events on wastewater treatment processes." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001609.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

McMahan, Erin K. "Impacts of Rainfall Events on Wastewater Treamtent Processes." Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3846.

Full text

Abstract:

Current research is revealing that stormwater can carry pathogens and that this stormwater is entering wastewater treatment facilities. During periods of intense rainfall, not only can stormwater carry higher amounts of pathogens, but it also increases the flow rate to the wastewater treatment facility. In many instances, the flow rate exceeds the facilities' treatment capacity and can impact treatment performance. The purpose of this study was to identify whether wastewater treatment is impaired during periods of increased rainfall, and to compare current policies that address this issue. The study was conducted using a case study approach to analyze historical precipitation and wastewater treatment data from facilities located in Clearwater and St. Petersburg, Florida. The effluent from the biological nutrient removal system operated at the facilities located in Clearwater was compared to the effluent from the activated sludge treatment system operated by the facility located in St. Petersburg. Statistical analyses were conducted to identify significant differences in either the loading or performance of wastewater treatment facilities under wet and dry flow conditions. In this case, the Clearwater facilities operating below their treatment capacity were better equipped to handle peak wet weather flows and efficiently treat wastewater than the St. Petersburg facility which has a less advanced treatment system and was operating at and above its treatment capacity.

APA, Harvard, Vancouver, ISO, and other styles

36

Selling, Benjamin. "Modelling Hydrological Impacts of Forest Clearcutting through Parameter Regionalization." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-267402.

Full text

Abstract:

The aim of this thesis was to test and evaluate whether parameter regionalization of a hydrological model can be used to model the impact of forest clearcutting on streamflow in Sweden. This is an important task to be able to perform water management and impact assessments adequately. The HBV conceptual rainfall-runoff model was applied for 218 Swedish catchments of different sizes that were spread across the country and covered a wide range of different forest cover percentages. The modelling approach included calibration of the model for each catchment using a genetic algorithm and then associating the resulting optimal parameter values with the percentage of forest cover. The obtained relationship between different model parameters and forest cover was validated with help of a paired catchment study site in northern Sweden where a clear cut was done in 2006: calibrated optimal parameter sets of pre- and post-clearcutting conditions were compared to parameter sets obtained from the Sweden-wide analysis. Correlations were found for about half of the fifteen hydrological model parameters, but the validation with the paired catchment study site could only partially confirm these obtained relationships. The results suggest that the adopted parameter regionalization approach is too basic. However, some of the results seem promising and emphasize the need for further research and development of the approach to provide a more reasonable method to model the impact of forest clearcutting on streamflow.
Det huvudsakliga målet med detta examensarbete var att testa och utvärdera om parameterregionalisering av en hydrologisk modell kan vara en lämplig metod för att modellera och kvantifiera påverkan från skogsavverkning på vattenbalansen i Sverige. Detta är en viktig uppgift för att kunna hantera våra vattenresurser och utföra konsekvensanalyser på ett tillfredsställande sätt. En konceptuell hydrologisk modell tillämpades på 218 avrinningsområden av olika storlekar och som var geografiskt utspridda i hela Sverige där även andelen skog i avrinningsområdena hade ett brett spektrum. Den använda modelleringsmetoden innefattade kalibrering av varje avrinningsområde genom att använda en genetisk algoritm, varefter de optimala parametervärdeana korrelerades mot andelen skog i avrinningsområdet. Idén med denna metod är att använda dessa potentiella samband för att justera modellparametrarna och därmed simulera en skogsavverkning. De erhållna sambanden mellan modellparametrarna och skogstäcket validerades med hjälp av data från en försöksstudie i norra Sverige där en skogsavverkning gjordes under 2006. Skillnaden mellan de bäst fungerande parametervärdena före och efter skogsavverkningen jämfördes med de tidigare sambanden från andra avrinningsområden i Sverige. Signifikant korrelation hittades för ungefär hälften av de 15 hydrologiska modellparametrarna, men valideringen mot den riktiga skogsavverkningen kunde bara delvis bekräfta de erhållna sambanden. Resultaten visar att detta sätt att använda parameterregionalisering antagligen är för grundläggande. Vissa resultat är ändå lovande och fortsatt forskning och utvidgning av metoden är nödvändig för att kunna tillhandahålla en rimlig metod för att kvantifiera en skogsavverknings effekter på vattenbalansen.

APA, Harvard, Vancouver, ISO, and other styles

37

Boyard-Micheau, Joseph. "Prévisibilité potentielle des variables climatiques à impact agricole en Afrique de l'Est et application au sorgho dans la région du mont Kenya." Thesis, Dijon, 2013. http://www.theses.fr/2013DIJOS075/document.

Full text

Abstract:

Dans les pays du Sud ruraux et à faibles revenus, la vulnérabilité des zones agricoles pluviales, face à la variabilité pluviométrique, nécessite de trouver des solutions efficaces pour limiter les effets des aléas climatiques sur les récoltes. La prévision des caractéristiques des saisons des pluies quelque temps avant leur démarrage devrait aider à l’établissement de stratégies agricoles d’adaptation aux aléas pluviométriques. C’est à cet objectif que s’attache ce travail, appliqué à l’Afrique de l’Est (Kenya et nord de la Tanzanie), et articulé en 3 parties :- Définir et comprendre le comportement des descripteurs intra saisonniers (DIS) qui feront l’objet de l’étude de prévisibilité. Un travail spécifique a permis le développement d’une nouvelle approche méthodologique dans la manière de définir les démarrages (DSP) et fins (FSP) de saisons des pluies à l’échelle régionale. Cette approche basée sur une analyse multivariée, permet de s’affranchir des choix subjectifs de seuils pluviométriques imposés par les définitions communément utilisée en agro-climatologie. Une analyse de cohérence spatiale à l’échelle inter annuelle montre que, pour les deux saisons des pluies (long rains et short rains), le cumul saisonnier et le nombre de jours de pluie présentent une forte cohérence spatiale, tandis qu’elle est plus modérée pour le démarrage et fin des saisons et faible pour l’intensité quotidienne moyenne.- Analyser la prévisibilité des DIS aux 2 échelles spatiales régionale et locale en s’appuyant sur les simulations numériques du modèle climatique global ECHAM 4.5. Les précipitations quotidiennes simulées par le modèle, même après correction des biais, ne permettent pas d’appréhender correctement la variabilité interannuelle des DIS. Une spécification de la variabilité des DSP et FSP menée par le biais de modèles statistiques construits à partir d’indices climatiques observés, présuppose une prévisibilité modérée des deux descripteurs à l’échelle locale (régionale), et cela quelle que soit la saison. Le développement de modèles statistico-dynamiques à partir des champs de vents simulés par ECHAM 4.5, en mode forcé par les températures marines observées d’une part et prévues d’autre part, montre également des performances faibles localement et régionalement. - Explorer la manière dont la variabilité spatio-temporelle des paramètres climatiques et environnementaux module la variabilité des rendements de sorgho. Ces rendements sont simulés par le modèle agronomique SARRA-H à partir de données climatiques observées (1973-2001) dans 3 stations localisées à différentes altitudes le long des pentes orientales du Mt Kenya. Le cumul précipité et la durée de la saison expliquent une part importante de la variabilité des rendements. D’autres variables apparaissent comme jouant un rôle non négligeable ; le nombre de jours de pluies, l’intensité quotidienne moyenne ou encore certains DIS relatifs à l’organisation temporelle des pluies au sein d’une saison en font partie. L’influence des autres variables météorologiques est seulement visible pour les ‘long rains’ avec une covariation négative entre les rendements et les températures maximales ou, le rayonnement global. La date de semis semble jouer un rôle dans la modulation des rendements pour les stations de haute et moyenne altitudes, mais avec des différences notables entre les deux saisons des pluies
In Southern countries with rural low income populations, the vulnerability of rainfed agriculture to rainfall variability requires effective solutions to mitigate the effects of climatic hazards on crops. Predicting the characteristics of rainy seasons some time before they start should help the establishment of agricultural adaptation strategies to rainfall hazards. This is the objective of the present study, focused on East Africa (Kenya and northern Tanzania), and divided in three parts:- Define and document intra-seasonal descriptors (ISD) that will be considered in the predictability study. A new methodological approach has been developed in order to define the onset date (ORS) and the cessation date (CRS) of the rainy seasons at the regional level. Based on a multivariate analysis, it eliminates the subjective choice of rainfall thresholds imposed by the definitions commonly used in agroclimatology. An analysis of spatial coherence at interannual time-scale shows that for the two rainy seasons ("long rains" and "short rains"), the seasonal amount and the number of rainy days have a high spatial coherence, while it is medium for the onset and cessation dates and low for the average daily rainfall intensity.- Analyze the predictability of the ISD at both regional and local scales based on numerical simulations from the global climate model ECHAM 4.5. Daily precipitation simulated by the model, even after bias correction, do not correctly capture the IDS interannual variability. A specification of the ORS and CRS variability using statistical models applied to observed climate indices, suggests quite a low predictability of the descriptors at the local (regional) scale, regardless of the season. The development of statistical-dynamical models from wind fields simulated by ECHAM 4.5, in experiments forced by either observed or predicted sea temperatures, also shows quite poor skills locally and regionally.- Explore how the space-time variability of climatic and environmental factors modulate the variations of sorghum yields. Crop yields are simulated by the agronomic model SARRA-H using observed climate data (1973-2001) at three stations located at different elevations along the eastern slopes of Mt Kenya. The seasonal rainfall accumulation and the duration of the season account for a large part of the yields variability. Other rainfall variables also play a significant role, among which the number of rainy days, the average daily intensity and some ISD related to the temporal organization of rainfall within the season. The influence of other meteorological variables is only found during the long rains, in the form of a negative correlation between yields and both maximum temperature and global radiation. Sowing dates seem to play a role in modulating yields for high and medium altitude stations, but with notable differences between the two rainy seasons

APA, Harvard, Vancouver, ISO, and other styles

38

Philip, Priya. "Long-term rainfall variations and their impacts in the South West of Western Australia." Thesis, Griffith University, 2020. http://hdl.handle.net/10072/400559.

Full text

Abstract:

The South West of Western Australia (SWWA) has been of interest to research due to the decrease in rainfall over this region since the 1950s with a significant shift since the 1970s. SWWA depends on the winter rainfall for meeting its agricultural water requirements and town water supply. A decrease in rainfall has adverse impacts on these sectors. The decreasing trend has been attributed to the decrease in the magnitude and frequency of the westerlies which bring rainfall to this region and the major changes in the large-scale atmospheric phenomenon such as the Southern Annular Mode. The observed decline in water levels in the dams of this region indicates a decrease in runoff which is mostly a result of decrease in heavy rainfall. This suggests to the need to characterize the rainfall changes in SWWA both temporally and spatially. Total rainfall can be decomposed into light, medium and heavy rainfalls, and the land responds differently to these rainfall classes. The light and medium rainfall is crucial in replenishing the soil moisture which is beneficial to vegetation. While heavy rainfall contributes mostly to runoff flowing into dams, it also poses a higher risk of soil erosion compared to light and medium rainfall. This study aims to quantify contributions from these rainfall classes to the decrease and interannual variations in rainfall, and to relate the decrease to station characteristics, i.e., latitude, elevation and the mean annual rainfall, and to the largescale circulation pattern known as the Southern Annular Mode (SAM). The Southern Annular Mode (SAM) is the north south movement of the westerlies which are winds from west to east and occur in the midlatitudes between the 30˚ and 60˚ in the northern and southern hemispheres. Long-term data for 30 stations were used, and daily rainfall was divided into three classes in such a way that they contributed equally (one third of the total) to the total rainfall of each station. It was observed that the decrease in heavy rainfall was mainly responsible for the decrease in total rainfall, followed by the medium and light rainfalls. Stations with a higher rainfall along the coast were more likely to experience a decrease in rainfall than those in the drier inland areas. Stations, where rainfall was strongly correlated with SAM, were mostly concentrated along the west coast of SWWA and the SAM index explained 9% of the variation in heavy rainfall and 11% in total rainfall for the region. Rainfall volume is a crucial aspect because the precipitation over an area such as a catchment largely determines water resources availability for that area. Changes in the rainfall volume have considerable implications for regional water resources planning and management. As the rainfall volume is the product of the wet area, which is the area receiving rainfall and the rainfall depth, the change in rainfall volume is the result of change in rainfall depth or that in wet area or both. No study has yet been undertaken to examine the change in rainfall volume in SWWA. This study also aims to examine the spatial and temporal changes in rainfall volume and to attribute this change to that in the wet area and that in the average rainfall depth in SWWA. Gridded daily rainfall data at 0.05° resolution for the period from 1911 to 2018 were used for an area of 265,952 km2 in SWWA. The results showed that regions near the coast with mean annual rainfall ≥ 600 mm showed significant decreasing trends in rainfall volume, and 84% of which could be attributed to a decrease in the wet area, while the decrease in rainfall depth only played a minor role. The regions farther inland showed an increasing trend in rainfall volume although the trend was not statistically significant. The regions near the coast also showed a decreasing trend in wet area with a higher number of rain days while the regions farther inland showed an increasing trend in wet area with a lower number of rain days. In the coast, the rate of decrease in rainfall has been reduced, and heavy rainfall, in fact, has increased over past 30 years, although, there was no concurrent change in SAM. The runoff in SWWA has been steadily decreasing which has led to reduction in the water available for water supply and agriculture. The study aimed to understand the role of rainfall changes in the decrease of runoff in the study area. Daily rainfall, potential evapotranspiration and runoff data for 10 catchments in SWWA were used. It was observed that all catchments exhibited a decreasing trend in runoff while the rainfall showed an increasing trend in some catchments. Further, the rate of change in runoff was found to be 2.6 times the rate of change in rainfall. The AWBM model overpredicted the runoff suggesting the presence of factors besides the decreasing rainfall in the observed decrease in runoff. The results indicated that the decrease in rainfall has led to a persistent decrease in groundwater table, which accelerated the decrease in streamflow in the region. This study focused on the trend in rainfall of different intensities and their contribution to the total rainfall trend. It was found that the decreasing trend was mainly concentrated along the coastal region (high mean annual rainfall) while the inland region (low mean annual rainfall) experienced an increasing trend in rainfall. In other words, the wet regions were becoming drier and the dry regions were becoming wetter. The trend and variability in heavy rainfall was observed to be the major contributor to the variations in total rainfall. Rainfall volume along the coast also showed a significant decrease and this was mainly due to the decrease in wet area while the decrease in average daily rainfall depth only played a minor role. Although, in the long term, the rainfall shows a decreasing trend, in the recent period, the rate of decrease in the total rainfall has reduced and the heavy rainfall, in fact, has increased with no concurrent change in SAM. The decrease in runoff was not solely caused by the changes in rainfall, but the steady decline of groundwater levels in the region could also be contributing to the decreasing runoff. Although, in the recent years, the rate of decrease in rainfall has reduced, the groundwater in this region needs to first recover before we can observe any positive change in streamflow in this region.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
Full Text

APA, Harvard, Vancouver, ISO, and other styles

39

Zahid. "The influence of Asian monsoon variability on precipitation patterns over the Maldives." Thesis, University of Canterbury. Department of Geography, 2011. http://hdl.handle.net/10092/5891.

Full text

Abstract:

Asian climate varies on various spatial and temporal scales and has a wide spectrum of climatic characteristics. Climate variability, especially decadal to inter-annual scale rainfall variability across Asia has gained considerable attention of climatologists over the last century due to the fact that rainfall variability is known to have caused considerable damage to southern Asian nations. Until recent, much of the existing literature on southern Asian climate focused on India and it is only recently that studies have focused on countries other than India. Although the Maldives is a nation within southern Asia (lying in the Indian Ocean southwest of India), literature on precipitation patterns over the Maldives and its connection to the Asian monsoon is lacking. This thesis examines the variability of precipitation over the Maldives in relation to the Asian monsoon, since proper knowledge of the spatial and temporal variations of precipitation is essential for managing the water resources and agricultural sector of the Maldives. Yearly and monthly rainfall across the Maldives indicates that the rainfall varies temporally and spatially. Despite spatial variability of mean annual rainfall (January-December total) showing rainfall increasing from north to south, it was found that on average the northern and southern parts of the Maldives have received less rainfall during the monsoon season (May-November). This suggests that the mean annual rainfall maximum for the Maldives occurs between central and southern parts of the Maldives during the monsoon season. The Maldives monsoon rainfall is characterised by inter-decadal and inter-annual periodicities with a frequency of 12.9 and 2.5-4 years, and intra-seasonal periodicities (10-20 days and 30-60 day) in daily time series of monsoon rainfall for different regions of Asia. The fact that no objective criteria previously existed to identify monsoon onset and withdrawal dates in the Maldives, the criteria developed here for defining the monsoon season objectively for this region indicates that on average the rainy season or monsoon commences between 4 May and 13 May (mean onset dates based on outward longwave radiation (OLR) index and rain and wind criteria, respectively) and terminates in late November (21 and 23 November: mean withdrawal dates based on rain and wind, and OLR index criteria, respectively) for the Maldives. The mean length of the rainy season (LRS) based on the OLR index is 204 days, the mean LRS based on rain and wind is 11 days shorter (193 days). Results also demonstrate that the earliest monsoon onset for the Asian region occurs in the south of the Maldives in April. Correlation coefficient maps generated between Maldives monsoon rainfall and meteorological parameters suggest that the most significant parameters that influence the interannual variability of the Maldives monsoon rainfall (MMR) are mean sea level pressure, surface air temperature, OLR, sea surface temperature (SST), and the zonal wind and relative humidity at various levels. Temporal consistency checks carried out for these parameters with the MMR led to the elimination of some of these predictors (which have less influence in the variance of MMR). The predictors which explained a significant amount of variance in the MMR were retained, including surface relative humidity during April (SRHAPR), 850 hPa level relative humidity during May (850RHMAY) and 500 hPa relative humidity for May (500RHMAY). These parameters were then used to formulate a regression model (using backward regression) for the prediction of Maldives monsoon rainfall. The predictors included in the model account for a significant part of the variance (76.6%, with a correlation coefficient, CC = 0.9) in MMR, indicating the usefulness of the model for medium-range prediction of MMR before the core monsoon season commences. Global scale processes such as the El Niño-Southern Oscillation (ENSO) phenomenon influence the weather and climate around the globe, with ENSO considered to be one of the strongest natural phenomena influencing the climate of Asia on inter-annual time-scales. The association between the Maldives monsoon rainfall and ENSO events demonstrates that deficient/excess monsoon rainfall over the Maldives and India region is linked to the strong/moderate El Niño and La Niña events, respectively. During strong/moderate El Niño events, about 71.4% of the time the Maldives/India region experiences deficiencies in monsoon rainfall, while the Maldives/India region experiences excessive monsoon rainfall about 75% of the time during strong/moderate La Niña events. One of the regional scale processes that influence the climate of Asia is Eurasian snow cover. No previous studies have directly examined possible relationships between Eurasian snow and Maldives monsoon rainfall. The possible relationship between Eurasian snow cover (ESC) and the Maldives monsoon rainfall, explored in this research for the first time, appears to be only very weak. The results also demonstrate that the inverse relationship between the ESC and the Indian monsoon has weakened over recent decades. The correlation coefficient (-0.34) between Indian monsoon rainfall and ESC obtained for the 1973-94 period dropped to -0.18 for the 1979-2007 period. The inter-annual variability of the Indian and Australian monsoon rainfall experiences a remarkable biennial oscillation, which has been referred to as the tropospheric biennial oscillation (TBO). It is believed that the land and ocean surface conditions in March-May (MAM) over the Indo-Pacific region play an important role in monsoon transitions. The Maldives monsoon rainfall transition from relatively strong/weak to relatively weak/strong in consecutive years demonstrates a TBO connection (via a biennial tendency in Maldives monsoon rainfall). In relation to the Maldives monsoon rainfall, TBO strong years occur about 47.1% of the time, while weak TBO years occur about 52.9% of the time. Only some of the El Niño and La Niña onset years correspond to strong TBO years, with El Niño onset years (1982, 1987 and 2002) corresponding to weak TBO years, while La Niña onset years (1988 and 2000) corresponding to strong TBO years. Variability (spatial and temporal) in Maldives precipitation associated with global and regional scale processes results in flood and drought events that have downstream impacts, such as on water resources and the agricultural sector of the Maldives. Excess (wet) or deficient rainfall years identified for the period 1992-2008 indicate that the central region is most vulnerable to flooding (5 years with excess rainfall: 27.8% of the time), while the southern region is least vulnerable to both flooding (2 years with excess rainfall: 11.1% of the time) and drought (2 years with deficit rainfall: 11.1% of the time). The northern and central regions show an equal number of years with deficit rainfall (3 years: 16.7% of the time), indicating that they are equally prone to drought events. Furthermore, field survey results demonstrate that about 23, 31 and 37% households (respondents) from the northern, central and southern regions experienced flood events. About 79, 58 and 77% of the farmers from the northern, central and southern areas also experienced floods on their farms. On the other hand, field survey results also suggest that the 49-63% of the households in outer islands of the Maldives and 48-62% of farmers experience shortage of rainwater.

APA, Harvard, Vancouver, ISO, and other styles

40

Hedberg, Sofia. "Regional Quantification of Climatic and Anthropogenic Impacts on Streamflows in Sweden." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-269824.

Full text

Abstract:

The anthropogenic impact on earth’s systems has rapidly increased since the middle of the last century and today it is hard to find a stream that is not influenced by human activities. The understanding of causes to changes is an important knowledge for future water management and planning and of that reason climatic and anthropogenic impact on streamflow changes in Sweden were explored and quantified. In the first step trends and abrupt changes in annual streamflow were detected and verified with the non- parametric Mann-Kendall’s and Pettitt’s test, all performed as moving window tests. In the second step HBV, a climatic driven rainfall-runoff model, was used to attribute the causes of the detected changes. Detection and attribution of changes were performed on several catchments in order to investigate regional patterns. On one hand using smaller window sizes, period higher number of detected positive and negative trends were found. On the other hand bigger window sizes resulted in positive trends in more than half of the catchments and almost no negative trends. The detected changes were highly dependent on the investigated time frame, due to periodicity, e.g. natural variability in streamflow. In general the anthropogenic impact on streamflow changes was smaller than changes due to temperature and streamflow. In median anthropogenic impact could explain 7% of the total change. No regional differences were found which indicated that anthropogenic impact varies more between individual catchments than following a regional pattern.
Sedan mitten av förra århundradet har den antropogena påverkan på jordens system ökat kraftigt. Idag är det svårt att hitta ett vattendrag som inte är påverkat av mänsklig aktivitet. Att förstå orsakerna bakom förändringarna är en viktig kunskap för framtida vattenplanering och av denna anledning undersöktes och kvantiferades den antropogen och klimatpåverkan på flödesförändringar i svenska vattendrag. I arbetets första steg användes de Mann-Kendalls och Pettitts test för att lokalisera och verifiera förändringar i årligt vattenflöde. Alla test var icke parametriska och utfördes som ett glidande fönster. I nästa steg undersöktes orsakerna till förändringar med hjälp av HBV, en klimatdriven avrinningsmodell. Ett större antal avrinningsområden undersöktes för att upptäcka regionala mönster och skillnader. Perioder med omväxlande positiva och negativa trender upptäcktes med mindre fönsterstorlekar, medan större fönster hittade positiva trender i mer än hälften av områdena och knappt några negativa trender hittades. De detekterade förändringarna var på grund av periodicitet i årligt vattenflöde till stor grad beroende på det undersöka tidsintervallet. Generellt var den antropogena påverkan större påverkan från nederbörd och temperatur, med ett medianvärde där 7 % av den totala förändringen kunde förklaras med antropogen påverkan. Inga regionala skillnader i antropogen påverkan kunde identifieras vilket indikerar att den varierar mer mellan individuella områden än följer ett regionalt mönster.

APA, Harvard, Vancouver, ISO, and other styles

41

Fowler, Hayley Jane. "The impacts of climatic change and variability on water resources in Yorkshire." Thesis, University of Newcastle Upon Tyne, 2000. http://hdl.handle.net/10443/432.

Full text

Abstract:

Observational evidence and future climate change scenarios suggest an amplification of climatic contrasts across the UK. This is seen most prominently in the marked increase in notable flood events and drought episodes and may profoundly affect water resource systems in vulnerable areas, as exemplified by the 1995 Yorkshire drought. The 1995-96 drought resulted in severe stress to the Yorkshire water supply, necessitating the emergency measure of tanking in water from outside the region, and was caused by an unusual pattern of weather and precipitation. This research is an investigation into both natural climatic variability and possible future climate change in Yorkshire aiming to quantify the risk of future occurrence of severe drought events, such as that of 1995. Historical drought characteristics and spatial-temporal precipitation variability in Yorkshire are examined and linked to synoptic weather patterns. A multi-site stochastic rainfall model is then developed using conditioning by synoptic weather types. The model can account for spatial variability and allows the concurrent simulation of precipitation time-series for very different climatological sub-regions within the same water resource area. This model is used to investigate the impact of natural climatic variability and possible future climate change upon water resource reliability, resilience and vulnerability in Yorkshire. The structure of the stochastic rainfall model enables the impact of variations in weather type persistence or frequency to be investigated. In addition, rainfall model statistics can be altered to simulate instances of increased precipitation intensity or proportion dry days for example, for individual weather groups. The UKCIP98 Medium-High climate change scenarios for 2021- 2050 and 205 1-2080 are investigated using modifications to weather type frequency, precipitation and potential evapotranspiration. Results indicate that water resources in Yorkshire are likely to become more reliable on average under the examined climate change scenarios due to increased winter precipitation. However, model simulations also suggest a reduction in resource resilience and increased vulnerability to drought. Severe droughts comparable to that of 1995 show only a slight increase in frequency by 2080. However, there will be a significant increase in both magnitude and duration of severe drought, as a consequence of summer precipitation reductions and increased climatic variability. This methodology of simulating the impacts of potential atmospheric circulation change on precipitation regimes can provide a basis for the future planning and management of water resource systems.

APA, Harvard, Vancouver, ISO, and other styles

42

Walker, Clare. "Modelling the hydrological impacts of mechanised peat extraction on an upland blanket bog." Thesis, University of Huddersfield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327184.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Ortwine, Michelle L. "The impacts of rainfall runoff on tidal creek algal and bacterial production /." Electronic version (PDF), 2007. http://dl.uncw.edu/etd/2007-1/ortwinem/michelleortwine.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Chagnon, Frédéric J. F. (Frédéric Jacques F. ). 1975. "Patterns of shallow clouds and rainfall over the Amazon : climatic impacts of deforestation." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/28930.

Full text

Abstract:

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2005.
Includes bibliographical references.
(cont.) and, to a lesser extent, cold cloud patterns over the Amazon. Through complex interactions, the results reported in this thesis may have important implications for the local ecosystem dynamics of the Amazon, for the geomorphology of the Amazon river basin, for the flow regimes of the Amazon river, and for global climate.
The climatic impact of the current state of deforestation in the Amazon basin is examined in this thesis. Past modeling studies have shown that complete deforestation of the Amazon basin could result in dramatic decreases in regional rainfall and evaporation leading to desertification (e. g., Salati and Vose [1984], Shukla et al. [1990]). Yet, although 15% of the 4,000,000 km² Brazilian Amazon has already been deforested [INPE, 2003], current deforestation patterns in the Amazon basin are not uniform, nor do their extents surpass tens of kilometers. Numerical simulations indicate that idealized heterogeneities of land-surface properties could lead to organized mesoscale circulations that enhance convection (e. g., Anthes [1984], Chen and Avissar [1994a], Avissar and Liu [1996], Wang et al. [1998]); similar results were found in case-study simulations of actual Amazon deforestation (e. g., Wang et al. [2000], Roy and Avissar [2002]). Qualitative observations of enhanced shallow cloud cover over cleared areas have provided preliminary indications of episodic land-cover-driven mesoscale circulations in the Amazon basin (e. g., Cutrim et al. [1995], Durieux et al. [2003], Negri et al. [2004]). Based on these studies, the effects of the "fishbone" patterns of deforestation on shallow vection were thought to occur only episodically during few precious weeks toward the end of the dry season, and were largely accepted as being climatically insignificant. However, through the use of satellite data from the Geostationary Operational Environmental Satellite (GOES) and the Tropical Rainfall Measuring Mission (TRMM), this thesis quantitatively demonstrate that the complex pattern of deforestation in the Amazon has resulted in a climatic shift in shallow cloud, rainfall
by Frédéric J. F. Chagnon.
Ph.D.

APA, Harvard, Vancouver, ISO, and other styles

45

Ambrosino, C. "Rainfall variability in southern Africa : drivers, climate change impacts and implications for agriculture." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1322446/.

Full text

Abstract:

Southern Africa is characterised by a high degree of rainfall variability affecting agriculture among other sectors. The focus of this study is to investigate such variability and to identify stable relationships with its potential drivers in the climate system. These relationships are used as the basis for the statistical downscaling of climate model (GCM) outputs. From the simulated rainfall, indices representative of growing season characteristics are computed with the final purpose of studying the implications on maize cropping under a future climate change scenario. The analysis uses generalized linear models (GLMs), which allow the investigation of the relationships between different components of the climate system (geographical and climatic drivers) simultaneously. Initially, the effects of various climate indicators upon monthly regional (for all southern Africa) precipitation occurrences and amounts are characterised. Six climate factors are found to drive part of the rainfall variability in the region and their modelled effect upon rainfall occurrences and amounts agrees broadly with previous studies. Among the retained indices, relative humidity and El Niño accounted for the highest degree of explained variability. The location and intensity of the jet stream is also found to have a statistically significant and physically meaningful effect upon rainfall variability. Although effective for the analysis of monthly regional precipitation, and used to investigate future regional projections, the models do not perform adequately at more local spatial scales such as station locations or few km grids. The same methodology is, therefore, applied to characterise daily precipitation variability at multiple locations within a smaller region. The small scale statistical models capture adequately the seasonal and annual rainfall structure in the area. Indeed, the observations can not be distinguished from the simulated time series. However, the simulated rainfall values tend to be slightly too high throughout the seasons, possibly due to the spatial correlation structure not completely appropriate for such a complex region. From the simulated rainfall sequences, seven growing season indices (including the onset and length of the growing season, proportion of rainy days and total precipitation during the growing season) are derived and their projected change investigated under a climate change scenario. There is little consensus between the 18 selected GCMs, regarding changes in growing season indices between two investigated periods in the 20th and 21st centuries. For the next couple of decades the dominant source of variation in the indices appears to be the natural rainfall variability. Such information should therefore be taken into account when planning adaptation and mitigation strategies. The research presented here emerges as the first comprehensive assessment of different climatic factors linked to southern Africa rainfall variability as well as the first attempt to evaluate the GLMs suitability for the generation of rainfall sequences for agricultural impact studies.

APA, Harvard, Vancouver, ISO, and other styles

46

Shi, Ge. "Variability and change of the Indo-Pacific climate system and their impacts upon Australia rainfall." University of Southern Queensland, Faculty of Sciences, 2008. http://eprints.usq.edu.au/archive/00004784/.

Full text

Abstract:

[Abstract]: Australia is one of the driest continents in the world, and over the past decades, severe drought has plagued most of the country. Water security is an important national issue. The ultimate water supply, rainfall, however, is one of the most variable ones in theworld and is complicated by the fact that it is affected by several remote oceanatmospheric teleconnection systems simultaneously, including the El Niño-SouthernOscillation, the Indian Ocean Dipole and Southern Hemisphere oceanic and atmospheric variability. These three systems sometimes conspire to produce a severe impact, whereas sometimes they offset each other to produce a mild influence. The recent severe watershortage has generated a surge of investments with strong regional applications. The present study focuses on areas and issues outside the scope of these regional studies,aiming to provide an Australia-wide assessment of future Australian rainfall under climate change. Firstly, we unravel a process of the Indo-Pacific oceanic teleconnection and examine its role in influencing variability of the Indian Ocean, and hence Australianrainfall variations. An examination of their contribution to the warming structure of the Indian Ocean is carried out. Secondly, we explore dynamics of North West Australianrainfall variability and mechanisms of a rainfall increase over the past decades, and benchmark climate models in terms of their ability to reproduce the observed variability and trends, focusing on the role of increasing northern hemispheric aerosols in the rainfallincrease. Thirdly, we provide a dynamical explanation to the common future of a fast Tasman Sea warming rate under climate change, and identify the impacts of suchwarming on Australian rainfall. Finally, we examine the relative importance of the three systems, in addition to Tasman Sea warming, in driving rainfall changes undergreenhouse conditions. This project contributes to no less than six peer-reviewed journal publications.

APA, Harvard, Vancouver, ISO, and other styles

47

Saal, Lauren B. "Rainfall impacts on suspended sediment concentrations in an urbanized tidal creek, southeastern North Carolina /." Electronic version (PDF), 2005. http://dl.uncw.edu/etd/2005/saall/laurensaal.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Lee, Amanda Sean Peik. "Assessment of climate change impacts on rainfall series in Peninsular Malaysia using statistical methods." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39740/.

Full text

Abstract:

There is growing interest in quantifying the impact of climate change on extreme hydrologic events where failing to integrate the effect of climate change in rainfall estimation will underestimate the severity of the events and the adequacy of current hydraulic structure designs. The purpose of this study aims is to assess the rainfall trend and frequency analysis with impact from climate change in Peninsular Malaysia using statistical methods. The thesis consists of two sections, where the statistics of rainfall trend are assessed by Mann-Kendall (MK) test and non-stationary tests while the frequency analysis illustrates the changes in distribution functions that fit full series and sub-series of annual maximum rainfall. The study area is delineated into five regions according to their distance to the nearest coast (the different extents of the influence of monsoon to the study area) to examine the spatial characteristic of the rainfall series. The MK test has detected changes for each delineated region during different monsoon seasons. At the same time, the result of non-stationary tests reveal that changes in rainfall trend have developed around year 1995 in most of the stations (41% to 50% annual rainfall over the west coast regions; more than 50% of the short duration annual maximum rainfall in the central west region have shown non-stationarity). Among the regions, the short duration rainfall in central west region show most significant increasing trend by both the MK test and the non-stationary tests. Thus, year 1995 served as trend change-point to split full series data into two sub-series data and frequency analyses are performed on these data sets. From the outcomes of the frequency analysis using two sub-series data sets, the estimated quantiles from most of the regions have increased when the sub-series posterior to 1995 is used compared to full series data, implying an overall upward rainfall trend. The results also indicate that the combination of Generalised Extreme Value distribution function and L-moments for parameters estimation (GEV-LM) outperforms the other choices. The GEV-LM is able to fit well to all regions for short-duration rainfall and three regions for long-duration rainfall. This study demonstrates the importance of incorporating climate change in rainfall assessment. There are two-fold implications of this study. First, there is considerable variability of rainfall patterns due to climate change and hence, it is important to divide the study area into regions based on the results of the MK trend and non-stationary tests. Then, the best fitted distribution function and parameter estimation method combination for frequency analysis should be tested for every region. Second, it is important to appreciate the non-stationarity of rainfall series due to climate change and the impact on how frequency analysis shall be carried out. As the warming trends in Peninsular Malaysia started around year 1995, rainfall series have shown significance upward trend, while the results of the frequency analysis (estimated quantiles) reflects the changes in the rainfall characteristics as well. Hence, in this case, it is important to concern the non-stationarity in data to achieve better estimation performance using frequency analysis.

APA, Harvard, Vancouver, ISO, and other styles

49

Nuworsu, Eugene Kwaku Mawutor. "Modeling the Impacts of Changing Agricultural Patterns on Rainfall and Temperature in North Dakota." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31852.

Full text

Abstract:

Global climate change has been an issue of much concern for many years now with human activity being the main contributor to this phenomenon. However, some evidence in the United States Midwest suggests that there has been a decline in summer temperatures and a rise in summer rainfall as a result of increasing agricultural production in this region. This research applies a system of simultaneous equations more specifically a seemingly unrelated Tobit regression model to understand how land-use change and increasing crop production may be contributing to these changes in rainfall and temperature in the months of June, July, August and September in the state of North Dakota. The findings from the study indicate that corn production to some extent is contributing to increasing precipitation and declining temperatures in North Dakota.

APA, Harvard, Vancouver, ISO, and other styles

50

Hansingo, Kabumbwe. "An investigation into the impacts of the Benguela Niño on rainfall over southern Africa." Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/6479.

Full text

Abstract:

Includes abstract.
Includes bibliographical references (leaves 109-124).
The impacts of the Benguela Niño on southern African rainfall and circulation are investigated using an atmospheric general circulation model. The model used is the United Kingdom Met Office Hadley Centre Atmospheric General Circulation Model version 3 and experiments using idealizations of observed regional and remote SST anomalies during various Benguela Niño events were performed. It is found that SST forcing in tropical South East Atlantic induces a regional baroclinic response and that a Benguela Niño is capable of forcing anomalous wet conditions over western Angola on its own, via changes to uplift and evaporation over the SST forcing. It is also capable of forcing anomalous rainfall much further inland when the intensity is increased. An experiment with the tropical South East Atlantic SST anomaly shifted slightly further north produced a larger circulation and rainfall response in the model. Additional experiments with various SST anomalies in the South West Indian Ocean/central equatorial Pacific combined with those in the South East Atlantic were performed. These experiments are motivated by the fact that equatorial Pacific/South Indian Ocean SST anomalies of varying signs often occur at the same time as the Benguela Niño Events. The results suggest that depending on its sign, magnitude and location, SST forcing from the South West Indian Ocean may augment or oppose the southern African rainfall anomalies occurring during a Benguela Niño event to varying degree.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'IMPACT OF RAINFALL'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles