Дисертації з теми "Drought events"
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1
Cole, Andrew. "The response of grassland carbon cycling to drought events and changes in nutrient availability." Thesis, Lancaster University, 2016. http://eprints.lancs.ac.uk/86756/.
Анотація:
In grasslands, climate change has the potential to disrupt a range of ecosystem services, including agricultural production, carbon (C) storage and nutrient cycling. In particular, climate change is likely to increase the frequency and severity of extreme climate events, such as drought and the subsequent rewetting event. Yet the effect of drought events will not be consistent across grassland communities, instead likely varying with grassland properties. One such property may be the level of nutrient availability, which brings about changes in plant productivity, plant community composition, and soil microbial composition and function. In this thesis, the effect of reduced precipitation on C cycling in UK species-rich grasslands is investigated in two field experiments, with varying long-term grassland restoration treatments and short-term nutrient addition, and a glasshouse experiment with reduced soil moisture. It was hypothesised that changes in plant and soil microbial communities, brought about by differences in nutrient availability, would modulate above and belowground C cycling responses to drought. This thesis found that the level of nutrient availability was important for modulating how C is cycled in response to drought in plants, soil microbial communities and whole ecosystem CO2 fluxes. For plants, the effect of drought and nutrient availability differed between functional groups, species and due to intraspecific trait variation. For soil microbial communities, the effect of drought on carbon use efficiency was modulated by short-term nutrient addition. Increased nutrient availability and drought therefore interact to determine how C is cycled and stored in plants and soil microbial communities, revealing the importance of agricultural practices in modulating whole community responses to climate change. Overall, this thesis shows the mechanisms by which drought may alter C cycling and its potential feedbacks to climate are complex, but at least in part, depend on the level of nutrient availability.
2
Hausler, Melanie. "Assessment of the hydrological effect of drought and fire events on evapotranspiration at a regional scale." Doctoral thesis, ISA/UL, 2019. http://hdl.handle.net/10400.5/18337.
Анотація:
Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia / ULUntil today, there is only little knowledge about the behavior of actual evapotranspiration (ETa) before and after wildfires in Portugal, which can be estimated from remote sensing techniques. In this thesis, an existing Simplified Two-Source Energy Balance model (STSEB) was adapted, based on moderate resolution imagery to estimate ETa and its contributing parts of transpiration and evaporation. The study served to test the model and its precision. A bias of about 1 mm d1 for the estimated ETa was observed, where evaporation was regularly overestimated and transpiration underestimated. This error is acceptable for two-layer models based on satellite imagery, but estimates cannot be used for irrigation management. The evolution of the estimated ETa after wildfires (up to four years) was analyzed at eucalypt stands at the Caramulo mountain range in Portugal. By investigating the recovery of ETa after wildfire, the difference between burnt and unburnt stands was mainly related to fire severity and stand characteristics. Two to three years after the fire events, the difference between burnt and unburnt stands became nonsignificant for all severity classes. At the same region, the prediction of soil moisture deficit from drought indices was tested. The drought indices empirically estimate the dryness of an area and are directly related to fire danger. They are based on a simple water balance equation where effective rainfall and ETa are the only input and output, respectively. In this work the empirical equation of (ETa) was substituted by the estimated ETa from STSEB, which enhanced the spatial resolution of the drought indices, being regularly interpolated from point estimates. Spatial patterns of soil moisture deficit were predicted, which indicated a relationship to fire occurrences. To conclude, the ETa estimated by the remote sensing based STSEB model, was used to make observations of the water cycle on a regional scale. In contrast to other post-fire studies, eucalypt stands in Portugal were found to be subject to a smaller hydrological impact after wildfires. This implies a fast recovery and a smaller influence on streamflow and groundwater resources. Furthermore, the drought indices, using the ETa from STSEB, identified areas with higher proneness to drought, by improving the spatial resolution, using satellite imagery compared to traditional interpolation techniques. The results support fire danger rating and might help to improve fire regime and forest management
N/A
3
Rodrigues, Allan Soljenitsin Barreto. "Jornalismo e meio ambiente na Amazônia: a cobertura de eventos ambientais extremos pela imprensa escrita de Manaus." Universidade Federal do Amazonas, 2013. http://tede.ufam.edu.br/handle/tede/3140.
Анотація:
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Previous issue date: 2013-04-30This multidisciplinary research starts from these premises and has as objective the press coverage of the droughts taken place in Amazonas from 2005 to 2010. The question that guided this investigation was: Was the Amazon written Press able to efficiently inform its public about the drought phenomenona and its implications? To answer that question it was necessary to use methodological tools and theoretical structures of various areas of Social Sciences like Communication, Journalism, Sociology, Political Sciences among others. As a general goal, we had the analysis of the scientific and environmental information quality passed through Diario do Amazonas and A Crítica newspapers during the press coverage of both extreme climatic events. The methodology used was the quantitative and qualitative. In the quantitative area, it was used the content analysis since it is used to detect tendencies and criteria analysis models of noticing, framing and scheduling. The method consisted of the collecting and analysis, based on the fixed categories taking into account the journalistic principles and environmental issues approach of journalistic texts that deal with the droughts taken place in Amazonas. In the qualitative area, interviews were used with the intent of broaden out the analytical image beyond the message (news) focusing the communication process in a broader way, including source studies, the messengers (journalists) and receptors (readers). Joining the content analysis results and the information obtained from the interviews, we are able to infer the lack of quality information received by the readers from both main newspapers in Manaus, having as ground the journalistic principles and its scientific and environmental types. The investigation also pointed out the small contribution of the journalistic droughts coverage in Amazonas in 2005 and 2010 to the decision taking cleared up by the citizens of the main Amazon capital over the issues regarding global climatic changes. We identified the fragilities of the coverage and proposed ways to meet the requirements of the informative content regarding the environmental issues and its consequences in the Amazon.
Esta pesquisa tem como objeto a cobertura jornalística das secas ocorridas na Amazônia nos anos de 2005 e 2010. Nosso objetivo geral foi a análise da qualidade das informações científicas e ambientais passadas pelos jornais Diário do Amazonas e A Crítica durante as coberturas jornalísticas destes dois eventos climáticos extremos. A pergunta que presidiu a investigação concentrou-se na indagação se a imprensa escrita do Amazonas conseguiu ou não informar eficientemente seu público sobre os fenômenos das secas e suas implicações para a vida das populações. Para dar conta da resposta, foi necessário lançar mão de ferramentas metodológicas e arcabouços teóricos de várias áreas das Ciências Sociais, como a Comunicação, o Jornalismo, a Sociologia, a Ciência Política e outras. A metodologia assumiu a perspectiva das abordagens qualitativas e quantitativas. No aspecto quantitativo, utilizamos a análise de conteúdo pelo fato de ser uma técnica para detectar tendências e modelos de análise de critérios de noticiabilidade, enquadramentos e agendamentos. Este método compreendeu o recolhimento e análise, com base em categorias estabelecidas levando em conta os princípios do jornalismo e a abordagem da questão ambiental, dos textos jornalísticos que tratam sobre o fenômeno das secas ocorridas no Amazonas. No aspecto qualitativo, fizemos uso de entrevistas com o intuito de ampliar o espectro analítico para além da mensagem (reportagens) focalizando o processo comunicacional de forma mais ampla, incluindo o estudo das fontes, dos emissores (jornalistas) e dos receptores (leitores). Aliando os resultados da análise de conteúdo com as informações obtidas nas entrevistas conseguimos aferir a falta de qualidade da informação recebida pelos leitores dos dois principais jornais impressos de Manaus tendo como base os princípios do jornalismo e de seus gêneros científico e ambiental. A investigação também apontou a pouca contribuição da cobertura jornalística das secas no Amazonas em 2005 e 2010 para tomadas de decisão esclarecidas por parte dos moradores da principal capital da Amazônia sobre as questões relacionadas às mudanças climáticas globais. Identificamos ainda as fragilidades da cobertura e propomos caminhos para qualificar o conteúdo informativo acerca da questão ambiental e seus desdobramentos na Amazônia.
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Erfaneh, Sharifi. "Stochastic Modeling of Hydrological Events for Better Water Management." Kyoto University, 2016. http://hdl.handle.net/2433/217181.
Анотація:
Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第20006号
農博第2190号
新制||農||1045(附属図書館)
学位論文||H28||N5015(農学部図書室)
33102
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 藤原 正幸, 教授 村上 章, 准教授 宇波 耕一
学位規則第4条第1項該当
5
Phillips, Ian Douglas. "The occurrence, dynamical structure and prediction of drought events over Devon and Cornwall over a forty year period." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343455.
6
Vieira, Ricardo Jorge Almeida. "Biochemical and physiological changes on three commercial marine fish species to extreme weather events." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22233.
Анотація:
Mestrado em Biologia MarinhaThe effect of climate change is an issue of major concern to the scientific community and politicians, with the register, at the past decades, of extreme climate events worldwide. A biomarker based biomonitoring program represents a promising approach, due to its usage to assess the health status of organisms with the biochemical response may be used as early-warning signal of chemical (e.g. pollutants) and environmental stress conditions. However, it is of high importance to develop further approaches, to identify standard key species and organs to diagnose and determine damages caused by severe weather events in studies in situ. This work aims to investigate biomarker responses, in situ, in the liver and at the brain of three marine fish species (Dicentrarchus labrax, Platichthys flesus and Solea solea), from the Mondego estuary (Portugal), during two distinct extreme climatic events (drought (2012) and flood (2014)) in order to determine their baseline levels and to identify the organ to be used as endpoint in ecotoxicological studies. In addition, biochemical analyzes were supplemented with physiological indices of the sampled organisms, diagnosing their physiological state and implications for the antioxidant potential. Severe climatic events had distinct modes of action affecting the physiological condition of the studied species. Biochemical experimental approach shows that the brain has a low antioxidant defense system compared to the liver, increased ROS accumulation rates, making it particularly susceptible to oxidative damage during the dry event. In the flood event, the antioxidant potential of the brain compared to the liver revealed higher difficulty in detoxification of xenobiotic compounds. According to higher oxidative sensitivity of the brain, this organ shows to be a good indicator to assess the influence of climate change in aquatic ecosystems, using the liver as a reference organ, less sensitive to the factors above mentioned, although until now the organ often used in the analysis of oxidative metabolism.
Um assunto que tem requerido especial atenção por parte da comunidade científica e de políticos é o efeito das alterações climáticas, tendo-se registado nas últimas décadas eventos climáticos extremos cada vez mais frequentes mundialmente. A biomonitorização dos sistemas aquáticos baseada em análise de biomarcadores permite avaliar o estado fisiológico dos organismos e utilizar as respostas bioquímicas como sinais de alerta precoce de condições de stress ambientais ou químicos. Porém, é fundamental desenvolver e aprofundar estas metodologias de modo a identificar espécies aquáticas standard e órgãos chave que permitam diagnosticar os impactos provocados por fenómenos climáticos em estudos in situ. O presente trabalho tem como objectivo principal determinar as respostas in situ de biomarcadores analisados no fígado e no cérebro de três espécies de peixes marinhos (Dicentrarchus labrax, Platichthys flesus e Solea solea), recolhidos no estuário do Mondego (Portugal), em dois anos distintos, e sob a influência de eventos climáticos extemos (seca (2012), e inundação (2014)), de modo a determinar os níveis basais e identificar o órgão a ser usado como indicador em estudos ecotoxicológicos. As análises bioquímicas foram complementadas com índices fisiológicos dos organismos capturados, permitindo determinar o estado fisiológico dos organismos e implicações no sistema de defesa antioxidante. Os eventos climáticos extremos tiveram distintos modos de acção tendo-se registado no ano de seca a interrupção na dinâmica dos condutores ambientais, o que afectou a condição fisiológica das espécies estudadas. A análise bioquímica indica que o cérebro tem um sistema de defesa antioxidante baixo em comparação com o fígado, maiores taxas de acumulação de ROS, tornando-o particularmente susceptível ao dano oxidativo no ano de seca. O potencial antioxidante do cérebro comparado com o do fígado no ano onde se registaram inundações revelou maior dificuldade deste órgão na desintoxicação de compostos xenobióticos. De acordo com a maior sensibilidade oxidativa do cérebro, este órgão mostra ser um bom indicador na avaliação dos impactos das alterações climáticas nos ecossistemas aquáticos, utilizando o fígado como órgão de referência, menos sensível aos factores acima mencionados, no entanto, até ao momento, o órgão preferencial na análise do metabolismo oxidativo.
7
Skiadaresis, Georgios [Verfasser], Jürgen [Akademischer Betreuer] Bauhus, and Kerstin [Akademischer Betreuer] Stahl. "Effects of groundwater extraction and extreme drought events on vitality and growth of pedunculate oak (Quercus robur L.) trees." Freiburg : Universität, 2020. http://d-nb.info/1231711809/34.
8
Tran, Hoa Thi. "Integration of Geospatial Technologies in Monitoring Drought Events in a Coastal Area of Vietnam (Case study: Binh Thuan Province)." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/95471.
Анотація:
Drought is a climatic event regarding prolonged "drier than normal" conditions. Precipitation deficits, crop-moisture stress, soil-water unbalance, sudden stream flow cut-offs and low carrying capacity of ecosystems are responses to drought. Drought can occur in humid to arid climates, however, drought is more severe in arid and semi-arid areas due to the fact that in those distinctive areas, water resources are extremely limited and restricted. Additionally, local ecologies and ecosystems in arid regions are very fragile. Once a water competition occurs, critical services of ecosystems such as pure water, recreation, and land productivity will be threatened.
This research focuses on prolonged drought events that have been occurring more frequently in a coastal province of South Central Vietnam – named Binh Thuan. The study area is distinctive because its climate is characterized as one of the driest provinces in Vietnam. Annual rainfall in the North and near the coast of the province is less than 800 mm per year. During 6 months of dry season, there is almost no rain, or less than 50 mm. Due to precipitation deficits and high surface temperatures in recent years, meteorological droughts have occurred more frequently, and lasted longer, thereby stressing water resources for vegetation, wildlife, households, and industry. The occurrence of prolonged droughts has constrained economic activities in the coastal areas, especially agriculture and aquaculture. Furthermore, a long duration of dry conditions coupled with unsustainable land management (such as overgrazing), "drought-sensitive" soils in areas with sand and barren lands may introduce and accelerate risks of desertification processes (land productivity deterioration and unable to recover).
This research uses geospatial technologies to monitor drought severity and drought impacts on land use and land cover. Chapter 1 is a brief introduction and literature review of the drought context in Binh Thuan Province to place the research questions and objectives in content. Chapter 2 discusses the occurrence of meteorological droughts in Binh Thuan Province, then proposes climatic indices able to monitor this type of drought. Chapter 3 focuses on explaining and assessing uneven dry conditions that stressed vegetation health in the study area. This chapter investigates spatiotemporal distributions and frequencies of prolonged agricultural droughts using remotely sensed data and anomalies of precipitation distribution. Results indicate that coastal areas in the North of Binh Thuan are subject to severe droughts. Chapter 4 assesses human impacts on land management and practices in the study area during drought periods. Results show that in recent years (2010 to present), local governments and residents have implemented strategies to prevent sand dominance and to adapt to water shortages during dry seasons, such as vegetative cover, crop rotation with drought-tolerant plants and wind breaks. Accuracy was assessed using field data collected in the summer of 2016, in conjunction with Google Earth imagery.
In summary, this dissertation enhances understanding of drought events and impacts in Binh Thuan Province by considering different types of drought - meteorological and agricultural drought, and interactions of drought and human impacts upon land management and land practices during dry periods. Furthermore, findings and results of this research have demonstrated the effectiveness of remotely sensed datasets, and other geospatial technologies, such as geographic information systems, in modeling drought severity and in examining efforts and drought-adaptive practices of local residents. This work is a valuable foundation on which further studies can build to support policy development to protect and reserve soil-land productivity in Binh Thuan and other coastal regions of Vietnam affected by prolonged droughts.Doctor of Philosophy
Drought is a temporal climatic event with "drier than normal" conditions. While drought can occur in any climates, it can be more extreme in arid and semi-arid areas where annual rainfall and water resources are limited. Depending on types of drought, its presences and impacts may differ: (1) meteorological drought relates to a decrease of average rainfall/snowfall may resulting in moisture stress, (2) hydrological drought leads to a reduction of streamflow and groundwater, and (3) agricultural drought influences soil-water-crop balance or vegetation health. Prolonged drought – abnormally long duration of dry conditions, coupled with unsustainable management in water and land practice may cause losses of land productivity, promote soil erosion, and result in sand dominance in coastal areas. These land degradation processes can lead to "a desert-like condition" in impacted areas. This research concerns drought and its impacts in a coastal province in South central Vietnam, Binh Thuan. The study area is distinctive because its climate is characterized as one of the driest provinces in Vietnam. Annual rainfall in the North and near the coast is less than 800 mm per year, and during the 6 months of the dry season, there is almost no rain, or less than 50 mm. Due to precipitation deficits and high surface temperatures in recent years, meteorological droughts have occurred more frequently and lasted longer, stressing water resources for vegetation, wildlife, households, and industry. Additionally, unsustainable land management, such as overgrazing, coupled with movements of sand and barren lands from the coast inland, have accelerated the risks of land degradation. This research applies an integration of geospatial technologies for monitoring drought severity and impacts on land management and illustrates how local people have adapted to droughts.
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Chattopadhyay, Somsubhra. "IMPACT OF CLIMATE CHANGE ON EXTREME HYDROLOGICAL EVENTS IN THE KENTUCKY RIVER BASIN." UKnowledge, 2017. http://uknowledge.uky.edu/bae_etds/50.
Анотація:
Anthropogenic activities including urbanization, rapid industrialization, deforestation and burning of fossil fuels are broadly agreed on as primary causes for ongoing climate change. Scientists agree that climate change over the next century will continue to impact water resources with serious implications including storm surge flooding and a sea level rise projected for North America. To date, the majority of climate change studies conducted across the globe have been for large-sized watersheds; more attention is required to assess the impact of climate change on smaller watersheds, which can help to better frame sustainable water management strategies.
In the first of three studies described in this dissertation, trends in annual precipitation and air-temperature across the Commonwealth of Kentucky were evaluated using the non-parametric Mann-Kendall test considering meteorological time series data from 84 weather stations. Results indicated that while annual precipitation and mean annual temperature have been stable for most of Kentucky over the period 1950-2010, there is evidence of increases (averages of 4.1 mm/year increase in annual precipitation and 0.01 °C/year in mean annual temperature) along the borders of the Kentucky. Considered in its totality, available information indicates that climate change will occur – indeed, it is occurring – and while much of the state might not clearly indicate it at present, Kentucky will almost certainly not be exempt from its effects. Spatial analysis of the trend results indicated that eastern part of the state, which is characterized by relatively high elevations, has been experiencing decreasing trends in precipitation.
In the second study, trends and variability of seven extreme precipitation indices (total precipitation on wet days, PRCPTOT; maximum length of dry and wet periods, CDD and CWD, respectively; number of days with precipitation depth ≥20 mm, R20mm; maximum five-day precipitation depth, RX5day; simple daily precipitation intensity, SDII; and standardized precipitation index, SPI were analyzed for the Kentucky River Basin for both baseline period of 1986-2015 and the late-century time frame of 2070-2099. For the baseline period, the majority of the indices demonstrated increasing trends; however, statistically significant trends were found for only ~11% of station-index combinations of the 16 weather stations considered. Projected magnitudes for PRCPTOT, CDD, CWD, RX5day and SPI, indices associated with the macroweather regime, demonstrated general consistency with trends previously identified and indicated modest increases in PRCPTOT and CWD, slight decreases in CDD, mixed results for RX5day, and increased non-drought years in the late century relative to the baseline period. The study’s findings indicate that future conditions might be characterized by more rainy days but fewer large rainfall events; this might lead to a scenario of increased average annual rainfall but, at the same time, increased water scarcity during times of maximum demand.
In the third and final study, the potential impact of climate change on hydrologic processes and droughts over the Kentucky River basin was studied using the watershed model Soil and Water Assessment Tool (SWAT). The SWAT model was successfully calibrated and validated and then forced with forecasted precipitation and temperature outputs from a suite of CMIP5 global climate model (GCMs) corresponding to two different representative concentration pathways (RCP 4.5 and 8.5) for two time periods: 2036-2065 and 2070-2099, referred to as mid-century and late-century, respectively. Climate projections indicate that there will be modest increases in average annual precipitation and temperature in the future compared to the baseline (1976-2005) period. Monthly variations of water yield and surface runoff demonstrated an increasing trend in spring and autumn, while winter months are projected as having decreasing trends. In general, maximum drought length is expected to increase, while drought intensity might decrease under future climatic conditions. Hydrological droughts (reflective of water availability), however, are predicted to be less intense but more persistent than meteorological droughts (which are more reflective of only meteorological variables). Results of this study could be helpful for preparing any climate change adaptation plan to ensure sustainable water resources in the Kentucky River Basin.
10
Kulman, Denilson. "ANALYSIS OF LOCATION AND REFORM OF SETTLEMENTS OF VULNERABILITY FOR AGRICULTURAL DROUGHT EVENTS IN A RIO GRANDE DO SUL - 1981-2011." Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/9436.
Анотація:
Studies and surveys on climate phenomena serve to plan the geographical space. In
this sense, research has mainly focused on spatialization of the drought in Rio
Grande do Sul from 1981 to 2011 and the location of land reform settlements (PA).
The social issue was viewed from the location of land reform settlements and their
susceptibility to drought. The steps to performing the research consist of literature
review, data surveys in primary and secondary sources, such as INCRA and INPE.
For the treatment of information and preparation of final maps, the SPRING and the
QGIS software were used, along with Ordinary Kriging geostatistical technique. A
fieldwork was also carried out in selected settlements from the location in areas of
high drought occurrence in order to verify the susceptibility of the settlers. The results
are divided into two parts: use of GIS and geostatistical technique for obtaining the
spatial maps of drought occurrence per decade and synthesis map of occurrence for
the whole period of analysis and the PA location map per drought occurrence class.
The second part is the analysis and discussion of the results obtained in maps and
tables with information about the settlements, in order to support the territorial
planning.Estudos e levantamentos sobre os fenômenos climáticos servem para planejar o espaço geográfico. Nesse sentido, a pesquisa tem como objetivo central a espacialização da estiagem no Rio Grande do Sul no período de 1981 a 2011 e a localização dos assentamentos da reforma agrária. Abordou-se a questão social a partir da localização dos assentamentos da reforma agrária e sua vulnerabilidade a estiagem. As etapas de realização da pesquisa consistem em revisão bibliográfica, levantamentos de dados em fontes primárias e secundárias, como INCRA e INPE. Para o tratamento das informações e elaboração dos mapas finais utilizou-se os softwares SPRING, QGIS, e técnica geoestatística da Krigagem Ordinária. Também realizou-se trabalho de campo em assentamentos selecionados a partir da localização em área de alta ocorrência de estiagem com a finalidade de verificar a suscetibilidade dos assentados. Os resultados dividem-se em duas partes: utilização de SIG e técnica geoestatística para a obtenção dos mapas de espacialização de ocorrência da estiagem por década e mapa síntese da ocorrência em todo o período de análise e o mapa de localização dos PAs por classe de ocorrência da estiagem. A segunda parte consiste na análise e discussão dos resultados obtidos nos mapas e tabelas com informações sobre os assentamentos, com a finalidade de subsidiar o planejamento territorial.
11
Rudebeck, Hugo. "HYDROLOGICAL DROUGHTS IN SWEDEN: Mapping of historical droughts and identificationof primary driving climate variables andcatchment properties." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-350520.
Анотація:
This study investigated the relationship between hydrological, and to some extent, meteorological droughts, and meteorological variables and catchment characteristics in 235 Swedish catchments between 1983 and 2013. This was done in order to investigate what factors affect the drought sensitivity in Swedish catchments and to map the occurrence of droughts in Sweden between 1983 and 2013. There have been studies about which meteorological phenomena and catchment characteristics that promote hydrological droughts, but for Sweden this is relatively unexplored. To investigate droughts during the study period three indices were used: the Standardized Precipitation Index (SPI), which is an index for meteorological droughts, the Standardized Streamflow Index (SSI), which predicts hydrological droughts and a threshold index for streamflow droughts. These indices were used to identify the number of drought events and the total number of drought days. For the majority of the 235 Swedish catchments there were no significant trends for the number of drought events or the total number of drought days during the 30-year period. The SPI and the SSI were found to correlate best in time when adding a one-month lag period to the SSI time series. The correlations between the indices and the meteorological variables and the catchments properties varied depending on how the catchments were grouped according to latitude or elevation. For example, the number of drought events was positively correlated to the mean elevation of the catchments in north and central Sweden when using the SSI while there were no significant correlations with elevation in southern Sweden. Another example is that it was almost only in northern Sweden where significant correlations between the percentage of bedrock and drought characteristics were identified. The percentage of bedrock can be used as an indication for how much groundwater a catchment can store. The correlations also look different for the different indices. For example, when looking at all catchments together the number of drought events identified with the SPI was negatively correlated to latitude and mean elevation while the number of drought events identified with the SSI was positively correlated to the same variables. For further research into this topic it would be wise to study winter and summer droughts separately to better identify which are the driving variables.I den här studien undersöktes sambanden mellan hydrologiska, och till viss del meteorologiska, torrperioder och bakomliggande meteorologiska drivvariabler och avrinningsområdesegenskaper i 235 svenska avrinningsområden mellan 1983 och 2013. Detta gjordes i syfte att undersöka vilka faktorer som påverkar känsligheten för torka i svenska avrinningsområden och för att kartlägga förekomsten av torrperioder i Sverige mellan 1983 och 2013. Internationellt finns det studier på vilka meteorologiska fenomen och egenskaper hos avrinningsområden som leder till risk för fler torrperioder, men för Sverige är det ett relativt outforskat område. För att undersöka torrperioder under den aktuella perioden användes tre index: Standardized Precipitation Index (SPI), vilket är ett index för meteorologiska torrperioder, Standardized Streamflow Index (SSI), som används för hydrologiska torrperioder och ett tröskelvärdes-index för att identifiera hydrologisk torka. Indexen användes för att identifiera antalet torrperioder och totala antalet dagar med torka under studieperioden. För majoriteten av de 235 avrinningsområdena gick det inte att se några signifikanta trender för antalet torrperioder eller totala antalet dagar med torka under perioden 1983-2013. SPI och SSI korrelerade bäst med varandra över tiden när SSI-tidsserien försköts med en månad. Korrelationerna mellan torrperioderna identifierade med de olika indexen och de meteorologiska variablerna och avrinningsområdesegenskaperna varierade beroende på hur avrinningsområdena grupperades efter latitud eller medelhöjd. Till exempel, i norra och centrala Sverige korrelerade antalet torrperioder för SSI positivt med medelhöjden medan det i södra Sverige inte fanns några signifikanta korrelationer. Ett annat exempel är att det nästan bara var i norra Sverige som det fanns korrelationer mellan procenten berggrund och de identifierade torrperiodsegenskaperna. Procenten berggrund i jordlagret kan användas som en indikation på hur mycket grundvatten som kan lagars i ett avrinningsområde. Korrelationerna skiljde sig också åt för de olika indexen. Till exempel, sett över alla avrinningsområden så var antalet torrperioder beräknat med SPI negativt korrelerade med latitud och medelhöjd medan antalet torrperioder beräknat med SSI var positivt korrelerade med dessa egenskaper. För vidare forskning inom detta område rekommenderas att titta separat på vinter- och sommartorkor för att bättre kunna identifiera potentiella drivvariabler.
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Santos, Leonardo Valente dos. "Spatio-temporal dynamics of the zooplankton community of the Mondego estuary." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22788.
Анотація:
Mestrado em Biologia MarinhaEstuaries are among the most valuable and productive aquatic systems in terms of their services to human welfare. In the last decades it has been highlighted the importance of plankton (and mainly zooplankton) in the dynamic of aquatic food webs. Zooplankton plays a pivotal ecological role in terms of biomass and energy fluxes transference between primary producers and higher trophic levels, being raised the importance of this group in ecological studies. Furthermore, spatio-temporal scales of zooplankton communities’ structure and composition are an important focus in ecological research. Thus, the main aim of this work was to study the spatio-temporal dynamics and vertical distribution of zooplankton community in the Mondego estuary (Portugal), based on monthly field surveys conducted from May 2012 to March 2014, at the bottom and surface, with a mesh net size of 335 μm, in high tide. In addition, the influence of environmental variables (e.g. temperature, salinity, nutrients concentration) in the distribution of zooplankton communities was determined. The occurrence of a extreme climate events (drought and flood conditions) during the study period also allowed examining the effects of the extreme weather conditions on zooplankton ecology. The results showed variations in the distribution and abundance of various zooplankton groups related to drought and flood conditions during the studied period. The main variation in environmental parameters was register to the salinity and temperature levels, leading to the predominance of marine species during drought events. It was also possible to identify that these variations occur in the bottom and surface communities, however, at the bottom was not registered so drastic changes compared to the zooplankton composition from the surface.
Os estuários são dos sistemas aquáticos mais valiosos e produtivos em termos de bens e serviços para o bem-estar humano. Nas últimas décadas, evidenciou-se a importância do plâncton (e principalmente do zooplâncton) na dinâmica das cadeias tróficas aquáticas. O zooplâncton desempenha um papel ecológico fundamental em termos de transferência de fluxos de biomassa e energia entre produtores primários e níveis tróficos superiores, contribuindo para a importância deste grupo em estudos ecológicos. Além disso, escalas espaço-temporais da estrutura e composição das comunidades de zooplâncton são um foco importante em estudos ecológicos. Assim, o objetivo principal deste trabalho foi estudar a dinâmica espaço-temporal e a distribuição vertical da comunidade de zooplâncton no estuário do Mondego (Portugal), com base em campanhas mensais realizadas de maio de 2012 a março de 2014, no fundo à superfície, com uma rede de 335 μm de poro, em preia-mar. Determinou-se ainda a influência de variáveis ambientais (por exemplo, temperatura, salinidade, concentração de nutrientes) na distribuição da comunidade de zooplâncton. A ocorrência de eventos climáticos extremos (condições de seca e inundação) durante o período de estudo também permitiu determinar efeitos das condições climáticas extremas na ecologia do zooplâncton. Os resultados mostraram variações na distribuição e nas abundâncias de vários grupos de zooplâncton relacionados com condições de seca e inundações registadas durante o período de estudo. A principal variação nos parâmetros ambientais foi nos valores de salinidade e temperatura, levando ao predomínio de espécies marinhas em períodos de seca. Foi possível também identificar que estas variações ocorrem tanto nas comunidades de fundo como de superfície, no entanto, não se registam variações tão drásticas na composição da comunidade de zooplâncton no fundo.
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Driouech, Fatima. "Distribution des précipitations hivernales sur le Maroc dans le cadre d'un changement climatique : descente d'échelle et incertitudes." Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0065/document.
Анотація:
Dans le contexte du changement climatique, il est nécessaire d'affiner les informations relatives à l'évolution du climat dans un pays, susceptible d'être négativement impacté par le réchauffement global, comme le Maroc. En effet, les différentes études de projections futures, dont celles du GIEC, sont basées majoritairement sur les sorties de modèles climatiques à faible résolution qui ne permettent pas d'aborder les échelles régionales et locales. La première partie de ce travail concerne l'étude des tendances et évolutions observées au niveau du climat du Maroc à travers un certain nombre d'indices climatiques. Outre la forte variabilité interannuelle des précipitations et l'augmentation de la fréquence des sécheresses depuis le début des années 1980, la distribution des précipitations du Maroc a bien connu un changement au cours de la période 1961-2008. Ce changement, consistant en une évolution vers des conditions plus sèches, a coïncidé avec une augmentation de la température moyenne en toutes saisons. L'évaluation des changements futurs est réalisée tout d'abord à l'aide d'une descente d'échelle dynamique effectuée avec le modèle ARPEGE-Climat dans sa version à résolution variable. L'examen des capacités du modèle, dont la résolution est de l'ordre de 50km sur le Maroc, a montré son aptitude à simuler correctement la circulation de grande échelle ainsi que la variabilité interannuelle des précipitations marocaines en dépit d'une sous-estimation de leur quantité. A l'horizon 2021-2050, une baisse des cumuls généralisée à tout le pays concernerait la saison d'hiver (DJF). Si on se limite à la zone située à l'ouest des montagnes de l'Atlas, la baisse concernerait la partie la plus pluvieuse de l'année (ONDJFM). Cette baisse serait accompagnée d'une diminution du nombre de jours humides et du nombre d'événements de fortes précipitations ainsi que d'une augmentation de la persistance temporelle de la sécheresse. Ce changement de la distribution des précipitations coïnciderait avec un réchauffement qui se manifesterait à la fois aux échelles saisonnière et annuelle. Les sorties d'une dizaine de modèles régionaux de climat (MRC) du projet FP6-ENSEMBLES, sont utilisées pour balayer une partie de la marge des incertitudes relatives aux changements climatiques et notamment celles inhérentes à la modélisation. Les changements futurs issus de ces MRC, compatibles dans l'ensemble avec ceux issus d'ARPEGE-Climat, optent dans la plupart des cas pour une réduction des cumuls pluviométriques de l'hiver accompagnée généralement d'une baisse du nombre d'événements de fortes précipitations et d'une augmentation du nombre maximal de jours consécutifs secs. L'examen, réalisé à la fois à l'aide du modèle ARPEGE-Climat et des MRC d'ENSEMBLES, de la possibilité d'utilisation d'une méthode de réduction d'échelle statistique basée sur les régimes de temps de l'Atlantique nord pour la déduction des changements futurs des précipitations locales, montre la déficience de ce type d'approche dans le cas de la pluviométrie hivernale marocaine. La méthode de correction par quantiles étendues aux régimes de temps de l'Atlantique nord et appliquée aux sorties d'ARPEGE-Climat confirme le signe des changements issus de ce modèles, malgré un effet légèrement modérateur de leurs amplitudes. L'évaluation des impacts potentiels sur l'hydrologie à l'aide du modèle hydrologique GR2M et des scénarios climatiques d'ARPEGE-Climat, montre une future réduction des débits mensuels au niveau du bassin versant de la Moulouya du fait de la concomitance de précipitations moins abondantes et d'une évapotranspiration potentielle accrue par l'augmentation de température. Enfin, une descente d'échelle dynamique réalisée à l'aide du modèle à aire limitée ALADIN-Climat à très haute résolution (12km) sur la moitié nord du pays permet de confirmer dans l'ensemble les projections issues d'ARPEGE-Climat à la fois en termes de moyennes et d'extrêmesIn the context of climate change, it is important to improve climate information concerning countries that may be negatively impacted by global warming such as Morocco. Indeed, various studies of future projections, including IPCC ones, are mainly based on the outputs of low resolution climate models that do not allow accessing the regional and local scales. The first part of this work focuses on the study and analysis of observed climate evolution and trends in Morocco through a set of climate indices. Moroccan rainfall is characterized by a high interannual variability and more frequent droughts have occurred since the early 1980s. Furthermore, a clear change is shown in the distribution of precipitation during the period 1961-2008. It consists in a shift towards warmer and drier conditions. The assessment of future climate changes is done, firstly, using a variable resolution version of the global GCM ARPEGE-Climat with high resolution over Morocco (50km). The examination of this version capability shows the ability of the model to well reproduce the large scale circulation as well as the interannual variability of Moroccan rainfall despite an underestimation of its amount. A reduction of winter rainfall over the whole country is projected by the model for 2021-2050. In the region located west of the Atlas Mountains, the reduction could concern the wettest part of the year (ONDJFM). The changes in rainfall characteristics may also occur through a decrease in the number of wet days and the number of heavy precipitation events and by more persistent droughts. Furthermore, an increase of mean temperature is projected at annual and seasonal scales. The outputs of ten RCMs of the FP6-ENSEMBLES (ENSEMBLES) project are used to assess the uncertainties associated to future climate change. The changes issued from ARPEGE-Climat are in the range covered by the ten RCMs. Most of the models agreed on a reduction of winter precipitation associated with a decrease in the number of heavy precipitation events and an increase in the number of maximum consecutive dry days. The evaluation of a statistical downscaling approach that uses large scale fields such as North Atlantic weather regimes to construct local scenarios of future climate change shows the deficiency of this approach in the case of Moroccan winter precipitation. This result is obtained by both ARPEGE-Climat and the ENSEMBLES RCMs. The quantile-quantile correction method extended to weather regimes and applied to the outputs of ARPEGE-Climat confirms the sign of the changes despite a slight reduction of their amplitudes. The assessment of potential impacts on hydrology done using the hydrological model GR2M and the climate scenarios issued from ARPEGE-Climat shows a future reduction of the Moulouya watershed discharges. This is due to the combination of a rainfall decrease and an enhanced potential evapotranspiration induced by increasing temperature. Finally, a dynamical downscaling achieved using the limited area model ALADINClimat with very high resolution (12km) on the northern half of the country allows a further assessment of future climate changes and related uncertainties. The projections issued from ARPEGE-Climat are generally confirmed both in terms of average and of extremes
14
Karlie, Makeya. "Attribution of the 2015-2016 hydrological drought in KwaZulu-Natal to anthropogenic climate change." Master's thesis, University of Cape Town, 2020. http://hdl.handle.net/11427/32512.
Анотація:
In 2015-2016 Kwa-Zulu Natal (KZN) and other provinces in South Africa suffered from drought conditions. Drought can have negative impacts on the environment, society and the economy. Climate change is predicted to exacerbate extreme events such as droughts that would adversely affect already vulnerable regions such as KZN. The main aim of this study is to implement the attribution procedure, to determine if climate change has contributed to the 2015-2016 hydrological drought in selected KZN catchments. Methodology of the study followed a general framework of implementation of hydrological attribution experiments with climate data obtained from attribution simulations with HadAM3p global climate model. Prior to simulations in attribution mode, QSWAT model was set up for the study area and calibrated using SWAT-CUP and SUFI-2. Calibration results were poor but the model could be applied in the context of this study, under certain constraints. Results of attribution experiments revealed that for all 3 subbasins studied no increase of risk was observed and hence no influence of climate change on the 2015-2016 magnitude of drought for selected catchments was concluded by this study. These results are limited, as they are based on climate attribution experiments with only one climate model, rather than with a multi-model ensemble. Also, QSWAT model, in its implementation with generic climate data is of limited use in attribution (or hydrological) simulations as even after calibration the model performs poorly.
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Ecoto, Dicka Geoffrey. "Modélisation et apprentissage machine learning appliqués à l'estimation des dommages consécutifs à la survenance d'un événement de sécheresse par retrait-gonflement des argiles dans le cadre du régime d'indemnisation des catastrophes naturelles français." Electronic Thesis or Diss., Université Paris Cité, 2023. http://www.theses.fr/2023UNIP7182.
Анотація:
Cette thèse est consacrée à l'anticipation de l'impact financier sur les biens assurés de la survenance d'un événement de sécheresse grâce au recours à des méthodes au croisement de la statistique et du machine learning. Le terme sécheresse désigne ici le phénomène de retrait-gonflement des argiles provoquant des dommages aux bâtiments. L'exercice peut être décomposé en deux sous-problèmes que nous abordons tour à tour. Le premier sous-problème considère plus spécifiquement la tâche consistant à prédire quelles communes formuleront une demande de reconnaissance de l'état de catastrophe naturelle au titre de l'événement sécheresse. Le second est consacré à la prédiction de l'impact financier de l'événement sécheresse sur les biens assurés situés dans les communes reconnues en état de catastrophe naturelle. Dans le cadre du premier sous-problème, nous développons, étudions et appliquons un algorithme original pour la prédiction des demandes de reconnaissance de l'état de catastrophe naturelle. L'algorithme bénéficie de deux formalisations complémentaires de la tâche d'intérêt, abordé sous l'angle de la classification supervisée et comme un problème de transport optimal. Les prédictions finales sont obtenues comme moyenne géométrique des deux types de prédictions. Théoriquement, le plan de transport optimal peut être obtenu en appliquant l'algorithme iPiano [Ochs et al., 2015], dont nous prouvons que les hypothèses qui sous-tendent son analyse sont bien vérifiées. L'analyse des prédictions obtenues démontre la pertinence de l'algorithme. Dans le cadre du second sous-problème, nous développons, étudions et appliquons un algorithme original d'agrégation d'algorithmes inspiré du Super Learner [van der Laan, 2007]. Deux écueils doivent être pris en compte. D'une part, parce que le péril sécheresse n'est couvert par le régime d'indemnisation des catastrophes naturelles français que depuis 1989, le nombre d'événements sécheresse sur lesquels nous pouvons entraîner notre algorithme est réduit, chaque événement sécheresse se voyant associer un jeu de données de grande taille. D'autre part, à la dépendance temporelle s'ajoute une dépendance spatiale due notamment aux proximités géographique et administrative entre communes françaises. Fondée sur une modélisation de la dépendance à l'aide d'un graphe de dépendance, l'étude théorique révèle que la brièveté de la série temporelle peut être compensée si la dépendance spatiale est faible. De nouveau, l'analyse des prédictions obtenues démontre la pertinence de notre algorithmeThis Ph.D. thesis is dedicated to forecasting the financial impact on insured properties in the event of drought, utilizing methods that merge statistics and machine learning. In this context, "drought" refers to the phenomenon of clay shrinkage and swelling that leads to damage to buildings. The task can be broken down into two sub-problems that we address separately. The first sub-problem focuses on predicting which municipalities will submit a request for the government declaration of natural disaster for a drought event. The second is dedicated to predicting the financial impact of drought events on insured properties located in municipalities that obtained the government declaration of natural disaster for a drought event. For the first sub-problem, we develop, study, and apply an original algorithm to predict requests for the government declaration of natural disaster. The algorithm benefits from two complementary formalizations of the task at hand, approached as both supervised classification and an optimal transport problem. The final predictions are obtained as a geometric mean of these two prediction types. Theoretically, the optimal transport plan can be obtained by applying the iPiano algorithm [Ochs et al., 2015], and we demonstrate that the assumptions underlying its analysis are met. The analysis of the predictions obtained confirms the algorithm's relevance. Regarding the second sub-problem, we develop, investigate, and apply an original aggregation algorithm, inspired by the Super Learner [van der Laan, 2007]. Two challenges must be considered. First, since drought events have only been covered by the French natural disaster compensation scheme since 1989, the number of drought events available for training our algorithm is limited, with each drought event associated with a large dataset. Second, temporal dependence is compounded by spatial dependence, primarily due to geographic and administrative proximity between French municipalities. Based on a dependency modeling using a dependency graph, the theoretical analysis reveals that the brevity of the time series can be compensated if spatial dependence is weak. Once again, the analysis of the predictions obtained underscores the relevance of our algorithm
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Braz, Dejanira Ferreira, and Dejanira Ferreira Braz. "Impacto de eventos severos na agricultura do Rio Grande do Sul." Universidade Federal de Pelotas, 2015. http://repositorio.ufpel.edu.br:8080/handle/prefix/3459.
Анотація:
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Os eventos severos (ES) podem causar prejuízos econômicos e sociais, com danos na agricultura e pecuária de uma região. O Rio Grande do Sul (RS), por ter grande parte da sua economia baseada na agricultura, sofre diretamente com a ocorrência de ES ao longo do ciclo de desenvolvimento das culturas, o que pode acarretar em quebra de safras. O objetivo deste trabalho foi analisar a ocorrência dos ES que atingiram a agricultura no RS, e caracterizar espacial e temporalmente o ES mais frequente bem como sua distribuição temporal, a relação deste com o fenômeno ENOS e o impacto dentro das principais culturas do Estado. Para isto, foram utilizados dados de ocorrência de ES que afetaram a área rural por municípios do RS no período de 2003 a 2012, obtidos no banco de dados da Defesa Civil do RS (DCRS). Para a análise do impacto nas culturas agrícolas, foram utilizados os dados de produtividade, rendimento e valor bruto das culturas de arroz, soja, milho e trigo (EMATER e IBGE). Foi observado o registro de ES durante todos os meses de todos os anos, com maior frequência nos meses de verão e outono, sendo que os ES mais frequentes são estiagem, granizo e vendaval, respectivamente. A estiagem em geral ocorre com maior frequência nos meses de dezembro a julho, e em meses sem a atuação do fenômeno El Niño Oscilação Sul (ENOS). Mas ao compararmos a ocorrência dentro de cada fase de ENOS, observou-se que os casos de estiagem são mais frequentes em períodos de La Niña, nos meses de dezembro a março. Em relação à distribuição geográfica, a maior parte dos municípios atingidos por ano pela estiagem no RS estavam localizados na metade norte do Estado, embora a maioria das Regionais de Defesa Civil (REDECS) tenha registrado estiagem em todos os seus municípios pelo menos uma vez no período de estudo. Os anos com maiores danos para os agricultores do RS foram 2005, 2009 e 2012, sendo que a maior perda na produção final de grãos foi em 2012 em relação a 2011 foi de quase 100 milhões de toneladas de grãos. A intensidade da estiagem devido a atuação do fenômeno La Niña gerou déficit de precipitação à 296 municípios do RS, impactando diretamente na produção agrícola do Estado.
Severe events (ES) can cause economic and social losses, damage to agriculture and livestock in a region. The state of Rio Grande do Sul (RS), because much of its economy is based on agriculture, suffers directly with the occurrence of ES along with the development cycle of the crops, which can result in crop failures. The objective of this study was to analyze the occurrence of ES that hit agriculture in RS, and characterize spatially and temporally the most frequent ES and its temporal distribution, the relationship with the ENSO phenomenon and the impact within the state's major crops. For this, ES occurrence data were used that affected the rural area by RS municipalities from 2003 to 2012, obtained from the Civil Defense database RS (DCRS). For the analysis of the impact on agricultural crops, productivity data were used, yield and gross value of rice, soybean, corn and wheat (EMATER and IBGE). The ES log was observed during every month of every year, most often in the summer months and fall. And the most frequent ES are drought, hail and gale, respectively. The drought usually occurs more frequently between the months December to July, and months without the work of the El Niño Southern Oscillation (ENSO). But when comparing the occurrence within each ENSO phase, it was observed that cases of drought are more frequent during periods of La Niña in the months from December to March. Regarding geographical distribution, most of the municipalities affected by the drought year in RS were located in the northern half of the state, although the majority will of REDECS has recorded drought in all municipalities at least once during the study period. The worst years with further damage to farmers in RS were in 2005, 2009 and 2012, with the greatest loss in the final grain yield was in relation to 2012 and 2011 it was of nearly 100 million tons of grain. The intensity of the drought was because of the La Niña phenomenon that generated precipitation Deficit 296 municipalities in the RS, directly impacting production.
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Bambakidis, Theodore. "Changes in Benthic Algal Community Structure Following an Unpredictable Stream-Wide Desiccation Event." Bowling Green State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1245682807.
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Cordero, Mera Andrea Estefania. "Reservoir influences on droughts and floods characteristics in the Piedmont Region, Italy." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Анотація:
Among the consequences of global climate change, the alteration of hydrological cycles is one of the most worrisome, since it can result in an intensification of the characteristics of extreme events. In the Anthropocene era, human activities can further increase the frequency and magnitude of floods and droughts. Therefore, it is of utmost importance to analyse the influence of anthropogenic activities on the magnitude and frequency of hydrologic extremes. In the present work, Piedmont region (Italy) was taken as a case study. The work analyses 15 pairs of regulated up- and downstream catchments characterized by the presence of dam/reservoirs (hydroelectrical, irrigation and small artificial reservoirs). Following an analysis of the climate and hydrological regime of the catchments, based on the collection and spatial processing of hydro-meteorological time-series, a main general purpose has been assigned to each catchment and information on the reservoirs present in the basins were collected. Then, extreme events occurring in the last decades were identified using the threshold level approach with a constant and variable threshold for droughts, and the peak over threshold method for floods. The characteristics of the extreme events, such as duration, deficit/volume and intensity/peak were then computed. The quantification of the impact of the different dam/reservoir purpose was analysed through the paired-catchment analysis, which consists in the comparison of the drought/flood characteristics between up- and downstream catchments. The obtained results seem to indicate an overall alleviation of the severity of the drought and flood metrics downstream. It was also noticed that the magnitude of these changes is related to the dam/reservoir purpose (higher for hydroelectric purpose) and their volume. This study could be used as a first estimate of human influence (reservoirs) on hydrological extremes in Piedmont.
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Cooke, Kayleen. "Questions of resilience in municipal finance response to a shock event: a case study of the Cape Town drought." Master's thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/31167.
Анотація:
The gaining prominence of resilience in urban policy has meant that urban decision makers are increasingly being asked to exhibit foresight and preparedness in how the urban system is planned and managed. The City of Cape Town has accepted this principle of resilience as a key means of driving collective understanding and action within the urban system in a time of growing uncertainty. Cape Town recently experienced the worst natural disaster in the history of its city-dom, in the form of a three-year drought. The impact of this drought on the municipal budget has been formidable. In terms of expenditure, considerable adjustments to the planned expenditure had to be made in order to source the funds required for large-scale infrastructure projects designed to increase resilience within the municipal water supply. In terms of revenue, there is significant concern around the fiscal sustainability of the municipality as more and more households are developing their own water supply in the form of rainwater tanks and boreholes, which is anticipated to decrease the municipal revenue gained from water tariffs dramatically (CCT, 2018f). The story of how the municipal budget system was affected by and reacted to the drought provides an opportunity to observe the application of the City’s understanding of resilience to a complex system, where many actors undertake simultaneous and independent activities, and the impact of these activities is evident at multiple levels and across multiple systems and sub-systems.
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Melo, Davi de Carvalho Diniz. "Propagação de secas na bacia do Rio Paraná: do evento climático ao impacto hidrológico." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-31082018-164404/.
Анотація:
Desastres naturais (secas, enchentes, etc) têm resultado em perdas humanas e grandes prejuízos financeiros em diversos lugares do mundo. Os recentes períodos de seca ocorridos na região sudeste do Brasil mostraram a importância de se dispor de estratégias de mitigação dos efeitos decorrentes desses eventos extremos. Um pré-requisito para prever impactos desses eventos no futuro, é compreender como os mesmos ocorreram no passado, caracterizando-os espacial e temporalmente. Diante do exposto, o objetivo deste trabalho é quantificar os impactos regionais no sistema hidrológico causados por eventos extremos e identificar conexões entre as secas meteorológicas e hidrológicas, usando a bacia do rio Paraná como estudo de caso. Para tanto, foram identificados e caracterizados os principais eventos de seca ocorridos entre 1995 e 2015, analisaram-se as perdas de água nos componentes do balanço hídrico e no armazenamento total de água. Foram utilizados dados de sensoriamento remoto, incluindo medições da missão GRACE de anomalias no armazenamento total de água terrestre (TWSA), e estimativas de precipitação e evapotranspiração pelos satélites TRMM e MODIS, respectivamente. Simulações de modelos globais de assimilação de dados de superfície terrestre forneceram estimativas de escoamento superficial e umidade do solo. Foram coletados dados de 37 reservatórios para quantificar as perdas de água no armazenamento em terra. Os resultados mostram que o TWSA diminuiu 150 ± 50 km3 entre 2011 e 2015 na bacia do rio Paraná, o armazenamento dos reservatórios diminuiu 30% em relação à capacidade máxima do sistema com taxas de -17 a -25 km3 ano-1 durante as secas. Foram identificados seis grupos de reservatórios cujas respostas são variáveis de acordo com tipo de forçante (natural ou antropogênica) de maior controle. A análise dos tempos de resposta do sistema hidrológico sugere um tempo de até aproximadamente 6 meses para que medidas de combate às secas sejam tomadas. Este estudo ressalta as vantagens do uso combinado de dados de diferentes fontes em estudos regionais.Natural disasters have caused major economics and human losses globally. Recent droughts over Southeast Brazil underscored the importance of having mitigation strategies to fight the effects from extreme events and a prerequisite to anticipate the impacts from future events is an understanding of past droughts by means of spatial and temporal characterization. The objective of this study is to quantify regional impacts of extreme events on the hydrological system and identify linkages between meteorological and hydrological droughts. To this end, major droughts events between 1995 and 2015 were identified and characterized. Depletion in total water storage (TWS) and main components of the water budget were analyzed. Simulated soil moisture and runoff from land surface models and remote sensing data were used, including measurements of TWS anomalies (TWSA) data from GRACE mission, rainfall and evapotranspiration estimates from TRMM and MODIS satellites, respectively. To quantify reservoir storage depletion, data from 37 reservoirs were collected. Results show that TWSA declined by 150 ± 50 km3 between 2011 and 2015 in the Paraná basin; and reservoir storage decreased 30% relative to the system\'s maximum capacity, with negative trends ranging from -17 to -25 km3 yr-1 during the droughts. Six groups of reservoirs were identified whose response vary according to the main forcing type: human and/or natural controls. Analysis of the system\'s time lag responses indicated a 6 month window during which actions could be taken to combat the drought impacts. This study emphasizes the importance of integrating remote sensing, modelling and monitoring data to evaluate droughts and develop a comprehensive understanding of the linkages between meteorological and hydrological droughts for future management.
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Fileni, Felipe. "Vegetation-climate interactions in California – an in-depth analysis on the influence of climatic events across different Californian biomes." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-442370.
Анотація:
It is widely accepted that climate variability is a key driver of vegetation productivity. Yet, there are discrepancies on the ideal timescales of climatic events and vegetation response. The work herein attempts to clarify how those variables interact in the region of California. The Standard Precipitation Evapotranspiration Index (SPEI), a drought index, was used as an indicator of interannual climate variability in the region. Vegetation productivity was accounted with Normalized Difference Vegetation Index (NDVI) or net growth point data. In this study, four parameters were tested: the length of climate events influencing vegetation, the ideal time to be accounted as vegetation response, the start of the growing season, and the lag between climate and vegetation response. In total, 594 different scenarios were simulated, with 432 considering the correlation between SPEI and NDVI anomalies and the remaining between SPEI and net growth. The findings shows that the Hot Deserts of California have an early start of the drought season, in March or April, with climate events from 6 months prior influencing vegetation greenness for the next 3 months. In those deserts, the direct correlations between SPEI and NDVI have been the highest, of 0.70 (Mojave) and 0.64 (Sonoran), meaning that, in these locations drier periods will decrease vegetation health. Cold Deserts present a later start of the drought season, in May. Vegetation in these regions will have a delayed response to droughts, with scenarios of 1 to 2 months lags between climate events and vegetation response presenting the highest correlations between SPEI and NDVI. Response that is also longer with climatic events influencing the next 9 months of vegetation greenness. When the correlations were significant, Mediterranean California behaved similarly to cold deserts, with a lag between climate and vegetation, and even longer periods of climatic influence on vegetation, of up to 12 months. In colder regions of California, entailing the entire Western Cordillera, Cold Deserts, and some regions of Mediterranean California an inverse relationship between SPEI and NDVI was found. Drier periods early in the season, in March or April will cause vegetation to be greener during the following months. In cold deserts and Mediterranean California, this climate vegetation relationship happened for short climatic events, as only the previous months will have an impact on vegetation for the following three months. The Cordillera was influenced by longer climatic events, of up to three months, and was the location that showed the best inverse correlations between NDVI and SPEI. In these locations, an early snowmelt and higher temperatures, leading to higher evapotranspiration, could explain the increase in greenness of vegetation by drier periods. However, this observation does not hold when considering a larger scale of climatic events. The correlation between SPEI and Net Growth has showed that when longer periods are considered, with climatic events of 12 or 24 months, a decrease in the net growth of plants will happen for the following season. As Californian climate is predicted to become more extreme it is of great importance understanding the possible consequences for vegetation.
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Vine, Michael David. "Between the event and the ordinary : climate crises and the ecologies of everyday life in the California desert." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/274463.
Анотація:
The notion of an environmental crisis or catastrophe conjures connotations of rupture, emergency, and impermanence: an intermediary moment of chaos in which the normal order of things collapses in on itself only to be brought back to life—or “recovered”—after the crisis is finished. It is by definition an event out of the ordinary, which in turn is idealised as the realm of routine, repetition, and the reproduction of the social order. But how might such crises permeate the body, home, and other ecologies of everyday life? And how might these ecologies be marshalled and transformed in a time of unfolding change? California is currently caught in a cascade of intersecting environmental crises, erupting most spectacularly with the state’s “historic” drought, which lasted from 2011 to 2017 and peaked in 2014/2015. Alongside the drought and its second order ramifications like wild fires and dust storms, the local manifestations of a changing climate are converging to generate among Californians a sense of near-constant crisis that is both powerful and widespread. Based on thirteen months' fieldwork from June 2014 to July 2015 in the arid lands of Central and Southern California, this thesis examines everyday lived experiences of space and time amidst this scene of instability and uncertainty. Each chapter tracks from a different vantage point the ways in which people are experimenting with the material, practical, and symbolic elements of “the ordinary” in response to the discontinuities introduced into daily life by forces beyond their control. It is my assertion that these ongoing and open-ended practices are poorly captured by the concept of “recovery”—a recurrent figure in the anthropology of disaster—which strongly suggests a telos of return to some or another pre-disaster way of life. The central argument of the thesis, then, is that these processes of experimentation must be understood in an analytical framework that embraces rather than disavows the mutual absorption of the ordinary and the event. As such, the thesis examines the improvisational as well as the habitual aspects of everyday life, whilst also directing attention to the generative as well as destructive dimensions of environmental crisis. Sure enough, environmental crises can incite shock and trauma in those that live through them. At their most extreme, they may also reduce life to a state of bare survival. Yet my interlocutors also took great pride in their collective capacities not only to “weather the storm” but also to invent new modes of self-sufficiency in response to their altered physical circumstances. In doing so, they all drew heavily upon images of California’s past in order to make sense of their present and chart paths for future action. As such, the thesis will contribute to anthropologies of disaster, the ordinary, and historical imagination and practice in the contemporary United States.
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Binda, Andrey Luís. "Eventos hidrológicos extremos e morfodinâmica fluvial em área afetada por processos de arenização no sudoeste Do Rio Grande Do Sul – Bacia Hidrográfica Do Arroio Miracatu." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2016. http://hdl.handle.net/10183/148271.
Анотація:
Os processos de arenização no sudoeste do Rio Grande do Sul têm sua explicação na relação entre a fragilidade do meio e a dinâmica hídrica, esta sustentada por eventos torrenciais de chuva. A presença de processos erosivos sob a forma de ravinamentos e de voçorocamentos e a exposição das formações superficiais nos areais atestam, nessa área, elevada mobilidade de sedimentos. Além disso, atividades agropecuárias sem o manejo adequado têm intensificado esses processos naturais, ampliando a interação hidrossedimentar entre as vertentes e os fundos de vale. Embora haja inúmeros trabalhos que abordam o processo de arenização e as dinâmicas do espaço geográfico no sudoeste do Rio Grande do Sul, há ainda uma lacuna em pesquisas que visam compreender suas inter-relações com a morfodinâmica fluvial. Tendo como recorte espacial a Bacia Hidrográfica do Arroio Miracatu (BHAM), esta pesquisa visa analisar, justamente, a importância de eventos hidrológicos extremos na morfodinâmica fluvial e a sua interação com os processos de arenização. Dados de chuva e vazão da BHAM foram analisados com vistas a identificar o regime pluvio-fluviométrico. Para tanto foram empregados parâmetros estatísticos com a finalidade de discriminar os eventos mais comuns daqueles mais raros. Como a ênfase do trabalho são os eventos hidrológicos extremos, estes foram observados a partir de diferentes escalas temporais (anual, mensal, pentadal e diário) e relacionados tanto ao excesso, como à escassez hídrica. Os resultados apontam para uma elevada variabilidade nas chuvas, que tendem a se concentrar em um número reduzido de dias, tanto anualmente, como mensalmente. Uma relação muito próxima entre a chuva e a vazão foi observada, de tal modo que os anos-padrão de chuva apresentaram correspondência com aqueles classificados pela Condição Hídrica da Bacia Hidrográfica (CHid). Isso decorre do fato de que tanto o El Niño Oscilação Sul (ENOS) como a Oscilação Decadal do Pacífico (ODP) modulam as chuvas e, consequentemente, as vazões na BHAM. Adicionalmente, foram identificados períodos ora mais secos (ODP-), ora mais chuvosos (ODP+). Esses períodos foram fundamentais para a compreensão da morfodinâmica fluvial, que é moldada por uma sucessão de regimes dominados por estiagem ou por inundação. Com a finalidade de avaliar esses processos de ajustamento foi selecionado um segmento localizado no médio curso da sanga da Areia. Nesse local a rede de drenagem é influenciada pelos processos de arenização, havendo conexão entre as vertentes e o fundo de vale, com intenso aporte de sedimentos. Com base em imagens de sensoriamento remoto (fotos aéreas e satélite) foi possível identificar a posição do canal em dez ocasiões diferentes, no período que se insere entre 1948-2013. Os ajustamentos que se processaram nesse segmento permitiram dividi-lo em dois trechos distintos (a montante e a jusante), com evolução diferenciada. Além dos ajustamentos na morfologia de canal, foram observados ainda variações na largura do canal, demonstrando ora um padrão entrelaçado (mais largo), ora meandrante (mais estreito). Concomitantemente a esses ajustamentos, a incisão fluvial promoveu a esculturação de diferentes feições, sendo possível delimitar dois níveis de terraços e um nível de planície de inundação. Na intenção de compreender os processos erosivo-deposicionais, procedeu-se ao monitoramento de nove seções transversais no trecho a montante do segmento estudado na sanga da Areia. O canal fluvial, inicialmente meandrante com calha estreita e profunda, passou para um padrão entrelaçado, com leito muito mais largo e raso ao fim do levantamento. Esses ajustamentos não se processaram de modo contínuo, mas bruscamente, em decorrência de pulso excepcional de cheia por ocasião de chuva pentadal extrema. Esse pulso promoveu um aumento brusco da carga sedimentar esculturando um canal entrelaçado (raso e largo) pela estocagem intracanal do material. Ajustamentos dessa natureza moldam a morfologia do canal e sugerem ocorrer de modo periódico na sanga da Areia.The sandization processes in the southwestern of Rio Grande do Sul State have their explanation on the relationship between environment fragility and water dynamics, and this, supported by torrential rain event. The presence of erosive processes in the form of ravines and gullies and the exposure of soil surface in the sand deposits attest, in this area, high sediment mobility. In addition, agricultural activities without appropriate management have intensified these natural processes, expanding water-sediment interaction between the slopes and valley bottoms. Although there are numerous studies that discuss the sandization process and the dynamics of the geographic space in the southwestern of Rio Grande do Sul, there is still, a gap in research aimed at understanding their interrelations with the fluvial morphodynamics. The Miracatu arroyo watershed was defined as the study area of this research, which aims to analyze the importance of extreme hydrological events in the river morphodynamics and their interaction with sandization processes. Rainfall and river-flow were analyzed in order to identify the rain-flow regime. For this purpose, statistical parameters were used in order to discriminate the most common of those rare events. The extreme hydrological events were observed from different time scales (annual, monthly, daily and pentad) and related either to excess, as the water scarcity. The results indicate a high variability in rainfall that tend to occur in a few days both annual as monthly. Was observed a relationship between rainfall and river-flow and it happens due the influence of El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) that modulate the rains and therefore the flow in Miracatu Arroyo. Furthermore, was identified a succession of drier (PDO-) and rainiest periods (PDO+). These periods were fundamental to the understanding of fluvial morphodynamics, once it allow characterize alternating drought- and flood dominated regimes. In order, to evaluate the fluvial adjustment processes were selected a segment-river located in the Areia Creek. In this place, the drainage network is influenced by sandization processes, with connection between the slopes and the valley bottom, with strong input of sediments. Based on remote sensing images (air photo and satellite) was identified the channel position in ten occasions in the period of 1948-2013. The fluvial adjustments that were processed in this segment allowed to divide it into two distinct reaches (upstream and downstream reaches), with different evolution. It was also observed variations in the width and channel pattern, sometimes showing a braided channel (wider) while in others a meandering course (narrower). Concurrently with these adjustments, the fluvial incision promoted the sculpturing of different features and it is possible define two levels of terraces and a flood plain level. The intention to understand the erosive-depositional processes proceeded to monitoring nine cross sections in the upstream reach of the segment-river studied in Areia Creek. The river channel, initially meandering with narrow and deep channel, passed for a braided pattern with bed wider and shallower at the end of the survey. These fluvial adjustments are not processed in a continuous manner, but abruptly, due to exceptional flood-pulse during extreme pentadal rain. This event promoted an abrupt increase in load-bed forming a braided channel (shallow and wide) by in-channel sediment storage. Adjustments of this nature shape the channel morphology and occur periodically in Areia Creek.
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Cavin, Liam. "Spatial and temporal patterns in the climate-growth relationships of Fagus sylvatica across Western Europe, and the effects on competition in mixed species forest." Thesis, University of Stirling, 2013. http://hdl.handle.net/1893/19992.
Анотація:
Increases in temperature, altered precipitation patterns, and the occurrence and severity of extreme climatic events have been important characteristics of the climate change observed to date. This has had many and diverse impacts upon the living world, with one recent observation being a global reduction in the net primary production of all terrestrial vegetation. Increases in temperature and the frequency of extreme events are predicted to continue throughout the 21st century, and can be expected to have far reaching effects on global terrestrial ecosystems. Increases in temperature and drought occurrence could fundamentally impact upon the growth rates, species composition and biogeography of forests in many regions of the world, with many studies indicating that this process is already underway. European beech, Fagus sylvatica, is one of Europe’s most widespread and significant broadleaved tree species, forming an important and frequently dominant component of around 17 million hectares of forest. However, the species is also considered to be drought sensitive. Thus, much research interest has focused on eliciting the details of its physiological response to increased water stress, whilst dendroecological studies have attempted to identify sites and regions where reductions in growth might be found. A significant knowledge gap exists regarding a multi-regional, range-wide view of growth trends, growth variability, climate sensitivity, and drought response for the species. Predicting the potential effects of climate change on competition and species composition in mixed species forests remains an important challenge. In order to address this knowledge gap, a multi-regional tree-ring network was constructed comprising of 46 sites in a latitudinal transect across the species’ Western European range. This consisted of 2719 tree cores taken from 1398 individual trees, which were used to construct tree-ring chronologies for each site in the network. As a first step in a multi-regional assessment for F. sylvatica, a combination of the tree-ring chronologies and environmental data derived from a large scale gridded climate dataset were used in a multivariate analysis. Sites in the latitudinal transect were partitioned into geographically meaningful regions for further analysis. The resulting regions were then studied using climate-growth analysis, pointer year analysis of drought years, analysis of growth trends and growth variability, in order to examine regional variation in the response of the species to climate. Furthermore, a combination of long-term monitoring data from one specific site was combined with tree-ring sampling of multiple cohorts of F. sylvatica and one co-dominant competitor, Quercus petraea, to study the effects of an extreme drought event in 1976 on mortality and subsequent recovery. Key results of the multi-regional analysis are that large scale growth reductions are not evident in even the most southerly and driest portions of the species’ range. Radial growth is increasing, both in the north and in the core of the species’ range, with southern range edge forests maintaining stable growth. However, the variability of growth from year to year is increasing for all regions, indicative of growing stress. Crucially, the southern range edge, which previous studies had identified as an ‘at risk’ region, was shown to be more robust than expected. Climate sensitivity and drought impacts were low for this region. Instead, forests in the core of the species range, both in continental Europe and in the south of the UK, were identified as having the highest climate sensitivity, highest drought impacts, and experiencing periodic reductions in growth as a result. Northern range edge forests showed little sign of being affected by drought, instead having low climate sensitivity and strongly increasing growth trends. Extreme drought was found to affect species differently: the dominant species (F. sylvatica) failed to recover pre-drought levels of growth, whilst a transient effect of competitive release occurred for the co-dominant species (Q. petraea). There was also a long term effect on the relative abundance of the two species within the woodland, due to differences in the levels of drought induced mortality experienced by the species. This shows that in the case of extreme climatic events where thresholds in the ability of species to tolerate water stress are breached, the effects of drought can be rapid and long lasting. Drought impacts can cascade beyond that experienced by the most drought sensitive species, due to changes in competitive interactions between species in mixed species forests. The implications of this work suggest opportunities, risks and strengths for F. sylvatica. In the northern portion of the species’ range, predicted increases in productivity are confirmed by recent growth trends, indicating a good outlook for the species. At the southern range edge, F. sylvatica forests exist either in locations where precipitation is high or locations where local environmental conditions buffer them from an inhospitable regional climate. These factors result in southern range edge forests which are highly resilient to the effects of increasing climate stress. It is instead in the core of the species’ range where the most sensitive forests are found. The effects of extreme drought on a range core forest demonstrated here provide a cautionary note: where drought stress tolerance thresholds are breached, rapid and long lasting effects on growth and mortality can occur, even in regions where drought has not previously been considered to pose a strong risk to the species.
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Ferrari, Gláucia Tatiana. "Imputação de dados pluviométricos e sua aplicação na modelagem de eventos extremos de seca agrícola." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/11/11134/tde-28062011-103251/.
Анотація:
Este trabalho relata o procedimento utilizado na obtenção de um banco de dados contínuo de precipitação diária de estações meteorológicas localizadas no Estado do Paraná. O banco de dados é composto por 484 séries históricas com dados entre janeiro de 1975 a dezembro de 2009. Para preencher os dados faltantes do banco de dados foram testados três métodos de imputação: o vizinho mais próximo, distância inversa ponderada e regressão linear. A raiz do erro quadrático médio (REQM) foi utilizada para comparar os métodos e o método da distância inversa ponderada proporcionou o melhor resultado. Após a imputação, os dados passaram por um processo de controle de qualidade que teve como objetivo identificar possíveis erros como precipitação idêntica em sete dias consecutivos (não aplicados a dados de precipitação zero) e valores de precipitação que diferem significativamente dos valores em estações meteorológicas vizinhas. Neste processo foram substituídos 1,21% valores de precipitação. Com o banco de dados contínuo, o interesse foi utilizar a teoria de valores extremos para modelar o período seco (número máximo de dias consecutivos com precipitação abaixo de 7mm para o período entre janeiro e fevereiro) crítico para a fase de enchimento de grãos da soja nas cinco principais mesorregiões (Centro Ocidental, Centro Sul, Norte Central, Oeste e Sudoeste) produtoras do Estado do Paraná. Pelo teste de Kolmogorov-Smirnov, ao nível de 5% de significância, a distribuição Gumbel foi a que melhor se ajustou aos dados de cada mesorregião e assim, a probabilidade de ocorrência de valores extremos de seca acima de 5, 25, 35 e 45 dias, o período de retorno para os maiores valores registrados em cada mesorregião e os níveis de retorno para o período de 5, 25, 50 e 75 anos foram calculados.This paper describes the procedure used to obtain a continuous database of daily precipitation from weather stations located in the state of Parana. The database consists of 484 time series with data from January 1975 to December 2009. To complete missing data from the database were tested three imputation methods: the nearest neighbour, inverse distance weighting and linear regression. The root mean square error (RMSE) was used to compare the methods and the inverse distance weighting method yielded better results. After imputing the data went through a process of quality control that aimed to identify possible errors as precipitation identical in seven consecutive days (not applied to precipitation data zero) and precipitation values that dier signicantly from the values in neighboring meteorological stations. In this process were replaced 1.21 % values of precipitation. With a continuous database, the interest was to use the Extreme Value Theory to model the dry period (maximum number of consecutive days with precipitation less than 7mm for the period between January and February) for the critical grain lling stage of soybean in ve main regions (Central West South Central, North Central, West and Southwest) producing state of Parana. Through the Kolmogorov-Smirnov, at 5 % level of signicance, the Gumbel distribution was best tted the data of each regions and therefore the probability of extreme values of drought over 5, 25, 35 and 45 days, the return period for the highest values in each and levels return for the period of 5, 25, 50 and 75 years were calculated.
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TimÃteo, SÃsthenis de Lima. "Guidelines struture of water safety Plan for extreme events : droughts and floods. Case study company of the situation room omplementation of Management Water Resources of CearÃ." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13686.
Анотація:
A Water Safety Plan for Extreme Events - PSAEE, has the purpose of description the procedures in potentially critical situations due to the occurrence of extreme weather
events (droughts and floods). Provides the developing of preventive actions and contingency plan as a way to mitigate the effects of these phenomena. Will be developed in different and complementary steps, aiming anticipation, recognition and risk assessment, identification and monitoring of vulnerable regions and the implementation of a warning network against Floods and Droughts. The present document describes guidelines for structuring a Water Safety Plan for Extreme Events, Floods and Droughts, structured in five (05) steps; 1. Preliminary Steps, 2 Diagnostic System; 3 Operational Monitoring; 4. Management Plans and 5.Validation and Verification. As a case study, the document analyzed the process of implementing the Situation Room of the Water Resources Management Company of Cearà - COGERH , also presenting some suggestion of a Work Plan for the Situation Room, which will serve as a Management Center of Extreme Hydrological Events for the State of CearÃ, Brazil.Um Plano de SeguranÃa de Ãgua para Eventos Extremos â PSAEE, tem como objetivo a descriÃÃo de procedimentos em situaÃÃes potencialmente criticas devido a ocorrÃncia de eventos climÃticos extremos (Secas e Cheias). Prevà o desenvolvendo de aÃÃes preventivas e plano de contingÃncia como forma de mitigar os efeitos destes fenÃmenos. Serà desenvolvido em etapas distintas e complementares, visando a antecipaÃÃo, reconhecimento e avaliaÃÃo de riscos, a identificaÃÃo e monitoramento de regiÃes vulnerÃveis, a implementaÃÃo de rede de alerta contra Cheias e Secas. O presente trabalho descreve diretrizes para estruturaÃÃo de um Plano de SeguranÃa de Ãgua para Eventos Extremos, Cheias e Secas, estruturado em 05 (cinco) etapas; 1. Etapas Preliminares, 2. DiagnÃstico do Sistema; 3. Monitoramento Operacional; 4. Planos de GestÃo e 5. ValidaÃÃo e VerificaÃÃo. Como estudo de caso, o trabalho analisou o processo de implantaÃÃo da Sala de SituaÃÃo da Companhia de GestÃo dos Recursos HÃdricos do Cearà â COGERH, apresentando, tambÃm, sugestÃo de um Plano de Trabalho para a Sala de SituaÃÃo, a qual servirà de Centro de GestÃo de Eventos Extremos HidrolÃgicos para o Estado do CearÃ, Brasil.
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RIVA, MARINA. "GESTIONE PARTECIPATA DELL'ACQUA E RISPOSTE ADATTIVE DEL SETTORE IRRIGUO A SEGUITO DI EVENTI DI CRISI IDRICA." Doctoral thesis, Università degli Studi di Milano, 2010. http://hdl.handle.net/2434/150088.
Анотація:
Droughts and extreme weather events have been highlighting for some years many water management problems, even where water is abundant and social-economic context is advanced, as it happens at our latitudes. It’s important to adopt new, multilevel, inclusive policy-making and management approaches in order to develop governance systems suitable to face current challenges, and consequently to mediate the rising conflicting stakes on water and to make more effective the investment in technological modernization.
In this context the case study of droughts events happened in Lombardy region between 2003 and 2007 turned out to be interesting. Developing a conceptual framework and making some interviews, the thesis characterizes the adaptive answer to such events from “water stakeholders” at the regional level, paying particular attention to irrigation sector.
The experiences of participatory water resources management, undertaken in those years, have allowed to the system to respond in emergency, have increased knowledge and social network, have started important remarks within the irrigation sector towards upgrade of innovation. However empirical evidences show that, in order to solve the emerging conflicts and develop an integrated and sustainable water resource management, is important, on the one hand, continuing to invest in participation, on the other hand, create a more stable regulatory framework.
28
(5930027), Ganeshchandra Mallya. "DROUGHT CHARACTERIZATION USING PROBABILISTIC MODELS." Thesis, 2020.
Анотація:
Droughts are complex natural disasters caused due to deficit in water availability over a region. Water availability is strongly linked to precipitation in many parts of the world that rely on monsoonal rains. Recent studies indicate that the choice of precipitation datasets and drought indices could influence drought analysis. Therefore, drought characteristics for the Indian monsoon region were reassessed for the period 1901-2004 using two different datasets and standard precipitation index (SPI), standardized precipitation-evapotranspiration index (SPEI), Gaussian mixture model-based drought index (GMM-DI), and hidden Markov model-based drought index (HMM-DI). Drought trends and variability were analyzed for three epochs: 1901-1935, 1936-1970 and 1971-2004. Irrespective of the dataset and methodology used, the results indicate an increasing trend in drought severity and frequency during the recent decades (1971-2004). Droughts are becoming more regional and are showing a general shift to the agriculturally important coastal south-India, central Maharashtra, and Indo‑Gangetic plains indicating food security challenges and socioeconomic vulnerability in the region.
Drought severities are commonly reported using drought classes obtained by assigning pre-defined thresholds on drought indices. Current drought classification methods ignore modeling uncertainties and provide discrete drought classification. However, the users of drought classification are often interested in knowing inherent uncertainties in classification so that they can make informed decisions. A probabilistic Gamma mixture model (Gamma-MM)-based drought index is proposed as an alternative to deterministic classification by SPI. The Bayesian framework of the proposed model avoids over-specification and overfitting by choosing the optimum number of mixture components required to model the data - a problem that is often encountered in other probabilistic drought indices (e.g., HMM-DI). When sufficient number of components are used in Gamma-MM, it can provide a good approximation to any continuous distribution in the range (0,infinity), thus addressing the problem of choosing an appropriate distribution for SPI analysis. The Gamma-MM propagates model uncertainties to drought classification. The method is tested on rainfall data over India. A comparison of the results with standard SPI shows significant differences, particularly when SPI assumptions on data distribution are violated.
Finding regions with similar drought characteristics is useful for policy-makers and water resources planners in the optimal allocation of resources, developing drought management plans, and taking timely actions to mitigate the negative impacts during droughts. Drought characteristics such as intensity, frequency, and duration, along with land-use and geographic information, were used as input features for clustering algorithms. Three methods, namely, (i) a Bayesian graph cuts algorithm that combines the Gaussian mixture model (GMM) and Markov random fields (MRF), (ii) k-means, and (iii) hierarchical agglomerative clustering algorithm were used to find homogeneous drought regions that are spatially contiguous and possess similar drought characteristics. The number of homogeneous clusters and their shape was found to be sensitive to the choice of the drought index, the time window of drought, period of analysis, dimensionality of input datasets, clustering method, and model parameters of clustering algorithms. Regionalization for different epochs provided useful insight into the space-time evolution of homogeneous drought regions over the study area. Strategies to combine the results from multiple clustering methods were presented. These results can help policy-makers and water resources planners in the optimal allocation of resources, developing drought management plans, and taking timely actions to mitigate the negative impacts during droughts.
29
Moura, Mikael Alvites. "The impact of drought events on the xylogenesis and phloem anatomy of Pinus pinaster Aiton saplings." Master's thesis, 2018. http://hdl.handle.net/10316/86152.
Анотація:
Dissertação de Mestrado em Ecologia apresentada à Faculdade de Ciências e TecnologiaClimate change is widely recognized as a significant threat to biodiversity and ecosystem services which will have an impact on forests. Climate change forecasts a temperature increase, irregular precipitation and intense drought, conditioning tree growth. The Mediterranean region is no exception, with a prediction of more intense droughts and reduced precipitation. In the first stages of development, tree mortality is high and thus it is increasingly important to understand the impact of drought on saplings. Pinus pinaster is an important species in the Portuguese and Mediterranean forest. To understand the impact of water availability on growth parameters, xylogenesis and phloem development of P. pinaster saplings, a water manipulation experiment was performed using 2-year-old maritime pines. The saplings were submitted to a drought period but also to an extra irrigation period (after the drought) to verify if the saplings could recover from an intense drought period. Four treatments were established: CC (control + control); CI (control + extra irrigation); EC (water exclusion + control) and EI (water exclusion + extra irrigation).In general, the saplings that were submitted to a water exclusion period showed a lower diameter and height. Concerning the xylogenesis, no differences were observed among the treatments when comparing the number of cambial cells, cells in enlargement (E), in lignification (L) and mature (M). However, the treatments that had the extra irrigation after the drought period, showed a higher rate in the production of mature cells (M and ELM cells) and of phloem, with the EI treatment showing the fastest recovery. Furthermore, the extra irrigation treatments also produced more tracheids during that period.Overall, the fact that saplings did resist to a drought period is very important for restoration and reforestation programs under stressful and unfavorable conditions because the early life stages of trees are important for the initial establishment of a forest.
As alterações climáticas são reconhecidas como uma ameaça significativa à biodiversidade e aos ecossistemas. Prevê-se um aumento da temperatura, um regime de precipitação irregular e de seca intensa, condicionando o crescimento das árvores. A região do Mediterrâneo não é exceção, onde estas previsões se aplicam. A taxa de mortalidade nas árvores é elevada nas primeiras fases de desenvolvimento, por isso é crucial perceber como estas condições afetam árvores jovens e/ou plântulas. Para tal, foi desenhada uma experiência de manipulação de àgua. Utilizaram-se plântulas de pinheiro-bravo (Pinus pinaster), uma espécie importante na floresta portuguesa e mediterrânica, para entender o impacto da seca ao nível de crescimento, xilogénese e desenvolvimento do floema. Foi realizada uma experiência com plântulas de dois anos de idade sujeitas a diferentes regimes hídricos, um grupo foi submetido a uma seca mais intensa, seguida de um período de irrigação extra (após a seca) e o outro grupo serviu como controlo. A irrigação após a seca foi aplicada para perceber se as plântulas conseguem recuperar após um período de falta de água. Assim, foram estabelecidos quatro tratamentos: CC (controlo + controlo); CI (controlo + irrigação extra); EC (exclusão de água + controlo); EI (exclusão de água + irrigação extra). Em geral, as plântulas submetidas à exclusão de água apresentaram alturas e diâmetros reduzidos. Em relação à xilogénese, não houve diferenças significativas entre os tratamentos em relação ao número de células do câmbio, células em fase de expansão (E), lenhificação (L) e maduras (M). No entanto, os tratamentos com irrigação extra apresentaram uma elevada produção de células maduras (M) e de floema, com o tratamento EI a apresentar uma recuperação mais rápida. O facto de as plântulas terem resistido à seca é muito importante para a restauração e reflorestação de florestas em condições desfavoráveis e de stress, uma vez que as primeiras fases da vida das árvores são importantes para o estabelecimento inicial de uma floresta.
30
Rito, João Manuel Cura. "The impact of extreme flood and drought events on the population dynamics of Scrobicularia plana (da Costa)." Master's thesis, 2009. http://hdl.handle.net/10316/13450.
Анотація:
Os ambientes marinhos estão entre os ecossistemas mais importantes do
planeta, tanto em termos ecológicos como sócio-económicos. O estuário do
Mondego, como muitos outros, providencia funções ecológicas essenciais,
serviços e óptimos habitats para muitas espécies e possui extrema importância
para a população humana local. Todos estes benefícios oferecidos por este
ecossistema podem estar em risco, visto que a frequência e a intensidade de
eventos climáticos extremos, tais como cheias e secas, tem vindo a aumentar
drasticamente nas últimas décadas, como resultado das alterações climáticas.
Estas perturbações afectam a qualidade geral do estuário, diminuindo a sua
produtividade através de impactos na abundância e biomassa das populações
e comunidades. O objectivo principal deste estudo foi analisar a resposta de
Scrobicularia plana, uma espécie dominante de bivalves na comunidade
macrobentónica do Mondego, à forte cheia de 2000/2001 e à seca extrema de
2004/2005. Esta espécie foi altamente afectada por estes dois eventos, mas de
diferentes modos. A cheia provocou uma total ausência de recrutamentos em
2001, a diminuição da biomassa e alterou a estrutura da população. A seca
causou um maior impacto na biomassa, o declínio na abundância geral e
também alterou a estrutura da população. A variação da salinidade da água no
estuário está directamente relacionada com a quantidade de precipitação. Os
valores extremos de salinidade alcançados durante as cheias e as secas são
uma das principais razões para a alteração da dinâmica populacional de
Scrobicularia plana. Tendo esta espécie uma extrema importância ecológica e
económica, os eventos extremos climáticos causaram grandes impactos
ecológicos e económicos na área em questão.
31
Satyanarayana, P. "Regional Frequency Analysis Of Hydrometeorological Events - An Approach Based On Climate Information." Thesis, 2009. https://etd.iisc.ac.in/handle/2005/1110.
Анотація:
The thesis is concerned with development of efficient regional frequency analysis (RFA) approaches to estimate quantiles of hydrometeorological events. The estimates are necessary for various applications in water resources engineering. The classical approach to estimate quantiles involves fitting frequency distribution to at-site data. However, this approach cannot be used when data at target site are inadequate or unavailable to compute parameters of the frequency distribution. This impediment can be overcome through RFA, in which sites having similar attributes are identified to form a region, and information is pooled from all the sites in the region to estimate the quantiles at target site. The thesis proposes new approaches to RFA of precipitation, meteorological droughts and floods, and demonstrates their effectiveness. The approach proposed for RFA of precipitation overcomes shortcomings of conventional approaches with regard to delineation and validation of homogeneous precipitation regions, and estimation of precipitation quantiles in ungauged and data sparse areas. For the first time in literature, distinction is made between attributes/variables useful to form homogeneous rainfall regions and to validate the regions.
Another important issue is that some of the attributes considered for regionalization vary dynamically with time. In conventional approaches, there is no provision to consider dynamic aspects of time varying attributes. This may lead to delineation of ineffective regions. To address this issue, a dynamic fuzzy clustering model (DFCM) is developed. The results obtained from application to Indian summer monsoon and annual rainfall indicated that RFA based on DFCM is more effective than that based on hard and fuzzy clustering models in arriving at rainfall quantile estimates. Errors in quantile estimates for the hard, fuzzy and dynamic fuzzy models based on the proposed approach are shown to be significantly less than those computed for Indian summer monsoon rainfall regions delineated in three previous studies. Overall, RFA based on DFCM and large scale atmospheric variables appeared promising. The performance of DFCM is followed by that of fuzzy and hard clustering models.
Next, a new approach is proposed for RFA of meteorological droughts. It is suggested that homogeneous precipitation regions have to be delineated before proceeding to develop drought severity - areal extent - frequency (SAF) curves. Drought SAF curves are constructed at annual and summer monsoon time scales for each of the homogeneous rainfall regions that are newly delineated in India based on the proposed approach. They find use in assessing spatial characteristics and frequency of meteorological droughts. It overcomes shortcomings associated with classical approaches that construct SAF curves for political (e.g., state, country) and physiographic regions (e.g., river basin), based on spatial patterns of at-site values of drought indices in the study area, without testing homogeneity in rainfall. Advantage of the new approach can be noted especially in areas that have significant variations in temporal and spatial distribution of precipitation (possibly due to variations in topography, landscape and climate).
The DFCM is extended to RFA of floods, and its effectiveness in prediction of flood quantiles is demonstrated by application to Godavari basin in India, considering precipitation as time varying attribute. Six new homogeneous regions are formed in Godavari basin and errors in quantile estimates based on those regions are shown to be significantly less than those computed based on sub-zones delineated in Godavari basin by Central Water Commission in a previous study.
32
Satyanarayana, P. "Regional Frequency Analysis Of Hydrometeorological Events - An Approach Based On Climate Information." Thesis, 2009. http://hdl.handle.net/2005/1110.
Анотація:
The thesis is concerned with development of efficient regional frequency analysis (RFA) approaches to estimate quantiles of hydrometeorological events. The estimates are necessary for various applications in water resources engineering. The classical approach to estimate quantiles involves fitting frequency distribution to at-site data. However, this approach cannot be used when data at target site are inadequate or unavailable to compute parameters of the frequency distribution. This impediment can be overcome through RFA, in which sites having similar attributes are identified to form a region, and information is pooled from all the sites in the region to estimate the quantiles at target site. The thesis proposes new approaches to RFA of precipitation, meteorological droughts and floods, and demonstrates their effectiveness. The approach proposed for RFA of precipitation overcomes shortcomings of conventional approaches with regard to delineation and validation of homogeneous precipitation regions, and estimation of precipitation quantiles in ungauged and data sparse areas. For the first time in literature, distinction is made between attributes/variables useful to form homogeneous rainfall regions and to validate the regions.
Another important issue is that some of the attributes considered for regionalization vary dynamically with time. In conventional approaches, there is no provision to consider dynamic aspects of time varying attributes. This may lead to delineation of ineffective regions. To address this issue, a dynamic fuzzy clustering model (DFCM) is developed. The results obtained from application to Indian summer monsoon and annual rainfall indicated that RFA based on DFCM is more effective than that based on hard and fuzzy clustering models in arriving at rainfall quantile estimates. Errors in quantile estimates for the hard, fuzzy and dynamic fuzzy models based on the proposed approach are shown to be significantly less than those computed for Indian summer monsoon rainfall regions delineated in three previous studies. Overall, RFA based on DFCM and large scale atmospheric variables appeared promising. The performance of DFCM is followed by that of fuzzy and hard clustering models.
Next, a new approach is proposed for RFA of meteorological droughts. It is suggested that homogeneous precipitation regions have to be delineated before proceeding to develop drought severity - areal extent - frequency (SAF) curves. Drought SAF curves are constructed at annual and summer monsoon time scales for each of the homogeneous rainfall regions that are newly delineated in India based on the proposed approach. They find use in assessing spatial characteristics and frequency of meteorological droughts. It overcomes shortcomings associated with classical approaches that construct SAF curves for political (e.g., state, country) and physiographic regions (e.g., river basin), based on spatial patterns of at-site values of drought indices in the study area, without testing homogeneity in rainfall. Advantage of the new approach can be noted especially in areas that have significant variations in temporal and spatial distribution of precipitation (possibly due to variations in topography, landscape and climate).
The DFCM is extended to RFA of floods, and its effectiveness in prediction of flood quantiles is demonstrated by application to Godavari basin in India, considering precipitation as time varying attribute. Six new homogeneous regions are formed in Godavari basin and errors in quantile estimates based on those regions are shown to be significantly less than those computed based on sub-zones delineated in Godavari basin by Central Water Commission in a previous study.
33
Ribeiro, Andreia Filipa Silva. "Development of an Agriculture Drought Risk model for the Iberian Peninsula." Doctoral thesis, 2020. http://hdl.handle.net/10451/48520.
Анотація:
Among climate extremes, droughts are a major source of risk to agriculture and food security, which are expected to be increasingly affected considering the tendency towards a warmer climate. Within the context of climate change, the Iberian Peninsula (IP) is one of the regions recurrently highlighted as one of the areas expected to be particularly affected by drought episodes, due to the strong variations in the precipitation regime that make the region prone to drought events. In this way, this dissertation aimed the development of an agricultural drought risk model to contribute to more resilient systems in the IP.
The skills of several drought indicators (SPEI, VCI, TCI and VHI) in predicting wheat and barley yields were firstly assessed based on neural networks and multiple linear regression models. Afterwards, copula-based models were designed to assess the joint probability of crop yields and droughts for a probabilistic risk assessment. The agricultural drought risk was then defined as the conditional probability of crop-loss under drought conditions and mapped at the province level of the IP. Ultimately, the additional risk associated with the occurrence of extreme temperatures during droughts was evaluated to characterize how the interaction between dry and hot conditions may exacerbate the impacts of the individual hazards in agriculture.
The results showed the good performance of drought indicators in predicting the occurrence of crop failures. In general, barley exhibits greater agricultural drought risk in comparison to wheat. Overall, the risk of crop-loss increases with the severity of drought conditions, and drought-related risks increase with the interaction with extreme temperatures. Although compound dry and hot conditions lead to the larger damages in crop yield than the individual drought- or heat-stress, drought is still the dominant factor. From an operational point of view, this research intends contributing to the agricultural decision-making.
34
Remelgado, Ruben Tiago Soares Lapa. "Analysis of in Situ measurements supported by earth observation data for the identification of drought events in South Tyrol." Master's thesis, 2013. http://hdl.handle.net/10451/20516.
Анотація:
Desenvolvido no seio do projeto ModEOalp, financiado pelo Instituto de Deteção Remota Aplicada, centro de investigaçao da Academia Europeia de Bolzano (EURAC), o presente trabalho de investigação providencia uma avaliação da eficiência da integração de dados de campo e de deteção remota para a identificação e avaliação de eventos de seca sobre a região da Tirol do Sul.
Como demonstrado em diversos estudos (Weingartner et al., 2009; Beniston, 2012; López-Moreno et al., 2012) desenvolvidos em torno do efeito das alterações climáticas sobre a neve na Grande Região Alpina (GRA), as alterações climáticas adquirem um papel fundamental, apresentando-se como uma problemática fundamental a médio e longo prazo à escala regional e continental. Devido à sua contribuição para a manutenção dos níveis de água de alguns dos maiores rios europeus (Danubio, Rhine e o Pó), a GRA adquire uma forte dimensão estratégica sendo a sua manutenção fundamental para garantir a subsistência das comunidades europeias. Apesar de o conceito de seca ainda não adquirir um papel expressivo no contexto da investigação desenvolvida em torno das alterações climáticas na região alpina, a variação da precipitação e da temperatura ao longo das ultimas décadas assim como as consequentes alterações verificadas sobre a neve apontam para ma crescente e preocupante tendência. Como demonstrado por Beniston et al. (1997 , 2002, 2012), embora as a alteração registadas ao nível da quantidade e densidade da neve precipitada durante o inverno ao longo dos últimos 60 anos não sugiram o alcançar de valores preocupantes assim como visíveis implicações para as comunidades que desta dependem para o abastecimento de água e para o desenvolver de atividades turísticas, a tendência negativa observada obriga à consciencialização por parte dos atores envolvidos para as suas possíveis repercussões. Consequentemente, a monitorização das condições meteorológicas assim como das alterações por estas criadas sobre a superfície assume um papel fundamental, contribuindo para a mitigação dos efeitos negativos originados por potenciais eventos de escassez de água.
Focando a sua atenção num período de 11 anos entre 2001 e 2011, a combinação dos métodos estatísticos e de SIG propostos e aplicados no âmbito do presente trabalho de investigação permitiram a avaliação do comportamento espácio-temporal das alterações climáticas na Tirol do Sul durante este período, contribuindo para a identificação de eventos climáticos extremos e para a observação das suas implicações sobre a vegetação e a neve. Enquanto que a neve se apresentar como um importante indicador das mudanças nos padrões meteorológicos a curto-prazo respondendo diretamente à precipitação recebida assim como às rápidas alterações da temperatura, a vegetação desempenha um papel fundamental, providenciando um indicador da intensidade dos eventos climáticos extremos observados, revelando o efeito da prolongada escassez de água e assinalando a presença (ou ausência) de eventos de seca. Consequentemente, a adoção de uma abordagem multi-temporal para a identificação torna-se essencial para a identificação de eventos de seca, permitindo a compreensão da influência cumulativas das alterações registadas e motivando a perceção de potenciais impactos sobre a superfície e contribuindo para a antecipação e mitigação de efeitos negativos sobre as comunidades humanas e naturais.
No âmbito do período de 11 anos considerado, a aplicação do SPI como um indicador de seca meteorológica assim como a estandardização da temperatura permitiram a bem-sucedida identificação de eventos climáticos extremos a várias escalas temporais, providenciando as bases necessárias para o desenvolvimento de futura investigação científica. Neste contexto, a utilização de imagens MODIS assume um papel fundamental no trabalho desenvolvido. A utilização de índices como o NDVI e o NDII assim como informação espacial da presença de neve sobre a superfície estudada potencializam a validação da análise estatística efetuada providenciando uma maior robustez a esta e criando as bases necessárias para a sua aplicação na monitorização do fenómeno estudado em superfícies topográficas complexas. Através da análise estatística aplicada, 2003, frequentemente referido como um importante pico na primeira década do século 21 devido à elevada intensidade das alterações registadas tanto no observado deficit de precipitação como no aumento das temperaturas, revelou elevadas anomalias positivas de temperatura assim como condições extremamente secas. Apesar disto, considerando as alterações das anomalias de precipitação a médio prazo, o período entre 2003 e 2007 adquire um papel comparativamente maior na compreensão das dinâmicas climáticas estudadas. Apesar de o SPI 24 apontar para uma baixa intensidade do deficit de precipitação após 2003, a presença continuada de um deficit de precipitação aliada à forte e acumulada acumulação de anomalias positivas de temperatura revelam a presença de um evento de seca a médio-prazo cujas consequências são visíveis pela aplicação de métodos de deteção remota, revelando a aplicabilidade de imagens de satélite de resolução moderada e da sua combinação com medições de campo para a monitorização das alterações climáticas e dos seus impactos sobre superfícies altamente complexas.Abstract: Developed in the scope of the ModEOalp project financed by European Academy of Bolzano (EURAC) research center Institute of Applied Remote Sensing, the presented research provides an evaluation of the effectiveness of integration of in situ and remote sensing data for the identification and evaluation of drought events over the region of South Tyrol. As shown by several studies developed on the effect of climate change on snow cover in the Great Alpine Region (Weingartner et al., 2009; Beniston, 2012; López-Moreno et al., 2012), climate change acquires a major role presenting itself as a large mid and long-term issue on both regional and continental level. Although the concept of drought still does not acquire a significant role within the alpine region climate change research, the variation of both precipitation and temperature during the last decades as well as the resulting changes in snow dynamics point to a growing and worrying tendency. Focusing its attention on an 11 year period between January 2001 and December 2011, the statistical and GIS methods proposed and applied within this research allowed for the evaluation of interannual variability of South Tyrol’s climate within this period, contributing for the identification of extreme climate events and for the observation of its implications over vegetation and snow. Although snow presents itself as an important indicator of short-term changes in meteorological patterns directly responding to incoming precipitation as well as to rapid changes in temperature, vegetation plays a major role, providing an indicator of the intensity of the observed extreme climate events revealing the effect of prolonged water scarcity and signaling the presence (or absence) of drought. Within the considered 11 year period, the application of the SPI as an indicator of meteorological drought as well as the standardization of temperature managed to successfully identify extreme climate events providing the basis for future investigation. In this contexto, the application of MODIS imagery assumes a fundamental role in the developed workflow. The usage of índices like NDVI and NDII as well as the spatial information of the presence of snow creates the potential for the validation of the performed statistical analysis as well as its application in the monitoring of the studied phenomena over complex topographic surfaces..Through the applied statistical analysis, 2003, usually referred to an important peak during the 21th century due to the high intensity of the registered changes in both precipitation deficits and temperature increases, showed significant changes during the Summer, revealing high positive temperature anomalies as well as extremely dry conditions. Despite this, considering the mid-term changes in precipitation anomalies, the period between 2003 and 2007 acquired a comparatively larger role within the studied climate dynamics. Although SPI 24 indicates to the presence of low intensity events pass 2003, the continued accumulated precipitation deficit allied to the strong and continuous accumulated positive temperature anomalies reveals the presence of a mid-term drought event which consequences over natural vegetation are visible through the application of remote sensing methods, revealing the application of moderate resolution satellite imagery and of its combination with in situ measurements for the monitoring of climate changes and its impacts over highly complex surfaces.
35
Collett, Ryan. "Assessment of a Food for Work Program and the Drought Survival Needs of Ethiopian Communities in the Northern Tigray Region." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10297.
Анотація:
The highland Tigray region of Northern Ethiopia has historically suffered significantly from drought shock events. These events, coupled with a high poverty rate- have left a severe impact on the agricultural output and community survival of the region. Several development interventions have been implemented in Ethiopia to address the effects of drought and poverty, the largest being the recent Food for Work Productive Safety Net Programme (PSNP). The purpose of this study was to assess the food security and drought survival needs of Ethiopian communities, more specifically, communities in the Northern Tigray Region. The main research questions were: (a) what are major themes from the permanent literature on the PSNP's management policies' impact at the beneficiary level; and (b) what are common needs of drought prone villages in the Tigray Region of Northern Ethiopia?
Research Question (a) was approached through content analysis of six purposely chosen peer reviewed journal articles related to the implementation of the first five years of the PSNP. Data was analyzed through the constant comparative method and two major themes emerged: Targeting Policy, and Transfer Policy.
To address Research Question (b), the researcher traveled to four drought prone villages in the Tigray Region and facilitated a combination of Participatory Rural Appraisal and Rapid Rural Appraisal techniques to assess community-level needs. Interviews with Non-Governmental Agency employees, Ministry of Agriculture and Rural Development employees, and University faculty provided institutional perspective to the research question. Data was analyzed using the constant comparative method and inductively formed into 11 themes, housed in three sectors: Economic Diversification, Environmental Management, and Social Coping Mechanisms.
The results of this study concurred with food security literature; namely that mechanisms for selecting intervention beneficiaries (i.e., targeting policy) and the process for distributing benefits (i.e., transfer policy) are practical concerns at the village level in Ethiopia. Analysis of participatory data formed a framework of community drought survival needs in the context of the Tigray Region. Asset building, water management, and human capacity are example needs which emerged from this study and should be addressed for the long term improvement of Ethiopia's resilience to drought shock events.
36
Musil, Jan. "Extremita odtoku v povodí horní Lužnice." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-343780.
Анотація:
Thesis subject is the evaluation of runoff and flood regime of rivers Lužnice and Skřemelice at the closing profiles just before their confluences. The results are compared with findings from the profile Pilař, which were published in the past by other authors. More attention is paid to the evaluation of the hydrological year 2013 and in detail is described the flood in June of the same year. Daily flow data from the years 1971 - 2014 were used for evaluating of runoff conditions. The assessment of the runoff regime in terms of daily, monthly and annual flows were compared with the runoff regime in Pilař gauge station. The source regions with dominating influence on the resulting runoff were discovered. Analysis of the flood regime confirmed that spring floods in Lužnice came mainly from upland and hilly parts of catchment and large summer floods have main source area in the catchment of Lužnice river itself, before the confluence of the Lužnice river and Skřemelic river. When assessing flood in 2013, the main source areas of flood flows that hit Lužnice river basin were founded. The flood extremity was compared in each closing profiles.
37
Hsu, Chih-Yang, and 許智揚. "The Study of Government’s Crisis Management: The Case of 2014-2015 Drought Event." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/29541679234631922785.
Анотація:
碩士國立中興大學
國家政策與公共事務研究所
105
In the recent years, more and more attention has been paid to issues in relation to global climate and environment change. The frequency and intensity of extreme events around the world have both been increasing. According to the records of the climate disasters occurring in Taiwan in the past 10 years, alternate flooding–drought conditions have become more and more frequent. The drought from September, 2014 to May, 2015 is the most serious drought in Taiwan in the past 67 years. The government’s responding measures and how it carried out tasks related to freedom of information and crisis communication during the process of crisis management are the topics this study discusses. The structural foundation of this study is the C3I system for dealing with a crisis suggested by Tsang (2000). This study reviews what the central government had done for crisis management during the drought from 2014 to 2015 from four major aspects, which are command, control, communication, and intelligence, and explores the factors causing droughts in Taiwan and the difficulties the government had had faced while fighting against droughts. The main finding of this study is that, besides insufficient rainfall, other causes of droughts in Taiwan include limited water storage and water use management. In the aspect of organizational operations in relation to responding measures for droughts, the findings are summarized as below: 1. more flexible manipulation with adaptability for crisis management and common consensuses between agencies are essential; 2. although there are already regulations regarding division of authority and responsibility for the drought responding mechanisms, the influence of selfish departmentalism should not be overlooked; 3. the process of fighting drought is also a long-term communication process; 4. in this process of fighting drought, the government used more diversified media instruments. However, there was still space for better internal communication; and 5. the government already started to collect related information from internet media and use communication software to help establish contact. In the aspect of the pressure the government felt or the challenge it faced, the findings are summarized as below: 1. externally, the main source of pressure and challenge is the questioning from the stakeholders of tap water; and 2. internally, the pressure and challenge lie in maintaining confidence in the government’s decisions in the long run. In the future, the frequency of droughts may increase. And this study provides the government the following suggestions to improve its responding mechanisms: 1. related laws and regulations should more appropriate to the times; 2. communication in peacetime between agencies which help to fight drought should be improved; 3. a training institution for spokesmen should be built; 4. the government should make good use of related technology such as new media; 5. the stability of water supply should be improved; and 6. education systems should be strengthened and concepts should be changed.
38
Kuo, Chin-Yuan, and 郭晉源. "Estimating the Effects of Drought Event Induced by Climate Change on Global Grain Production." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/8cg8h7.
Анотація:
碩士國立中興大學
應用經濟學系所
101
This study examines the impact of drought phenomenon on wheat, maize, and soybean’s production of the world by crop production model based on econometric panel data model. This study estimates the crops production on drought index of the world using the panel data model of major crops producing countries as examples. From empirical results, we come to the conclusion that drought index certainty have significant impacts on crops production. Results indicate that drought index have a significant negative impact on crops productions. The projection of future drought phenomenon for 2010s to 2090s reveals that the wheat production of world would change by -0.8％ to -4.1％ in response to the future drought incidence. Maize production of world would change by -0.7 to -7.32％. Soybeans production of world would change by 1.33 to -2.4％. Therefore, we suggest that the Government emphases on the issue of drought event induced by global climate change.
39
Monteiro, João Nuno Gomes. "Effect of extreme climatic events on Carcinus maenas population in the Mondego estuary." Master's thesis, 2019. http://hdl.handle.net/10316/88021.
Анотація:
Dissertação de Mestrado em Ecologia apresentada à Faculdade de Ciências e TecnologiaEventos climáticos extremos têm vindo a aumentar a sua frequência e intensidade nas últimas décadas. Deste modo, é importante compreender como estes afetam as espécies e habitats. O objetivo deste estudo foi analisar a variação temporal e espacial na dinâmica populacional de Carcinus maenas no estuário do Mondego, e os efeitos dos eventos climáticos extremos (secas e cheias) nesta população. As amostragens foram realizadas mensalmente durante os anos de 2003 a 2018 (exceto 2012 e 2013), durante a noite com o auxílio de uma rede de arrasto de vara de 2 metros. As densidades de C. maenas foram padronizadas em indivíduos por 1000m2. Analisando as densidades de juvenis observou-se a existência de um padrão de recrutamento contínuo ao longo de todo o estudo, com picos de recrutamento em anos de secas, além disso, é observável que os juvenis se encontram maioritariamente em zonas mais a montante do estuário. A população é constituída essencialmente pelo morfótipo verde, encontrando-se os indivíduos com morfótipos laranjas e vermelhos em zonas mais a jusante do estuário. O ratio sexual (machos/fêmeas) foi diferente conforme as classes de tamanho, apresentando valores superiores a 1 nas primeiras classes de tamanho, mostrando posteriormente, um equilíbrio do número de machos e fêmeas. A produção secundária (P) estimada para C. maenas foi diferente durante todos os anos do estudo, tendo valores superiores em anos de secas. Os diagramas de ordenação (RDA) mostraram as diferenças espaciais, temporais e ambientais de Carcinus maenas no estuário do Mondego. Através da análise das somas acumulativas (CUSUM) verificou-se uma correlação entre a maioria das características biológicas de C. maenas e as variáveis ambientais e o índice de oscilação norte atlântico (índice NAO). Avaliando as diferentes populações de caranguejo verde no planeta, observaram-se claras diferenças no período de recrutamento, no tamanho máximo dos indivíduos e na esperança média de vida. As populações do Sul da Europa apresentam menores tamanhos máximos e um maior período de recrutamento. Com o aumento da latitude, observa-se populações com maiores tamanhos máximos e com um menor período de recrutamento. A existência de eventos climáticos extremos leva à alteração da dinâmica populacional de Carcinus maenas, sendo que as maiores diferenças são observáveis durante secas extremas, onde devido à diminuição do caudal do rio e ao aumento da salinidade, irá existir um maior recrutamento de juvenis, levando assim a um aumento da densidade populacional.
Extreme climate events have been increasing in frequency and intensity in the last decades. So, it is important to understand how these affect species and habitats. The objective of this study was to analyse the temporal and spatial variation in the population dynamics of Carcinus maenas in the Mondego estuary and the effect of extreme climate events (droughts and floods) on this population. Samplings were performed monthly during the years 2003 to 2018 (except 2012 and 2013), with a 2-meter beam trawl during the night. The densities of C. maenas were standardized in individuals per 1000m2. Analysing juvenile densities, a continuous recruitment pattern was observed throughout the study, with recruitment peaks in years of droughts, in addition, it was observable that juveniles are found mainly in upstream areas of the estuary. The population consists essentially on the green morphotype, being the orange and red morphotypes present in more downstream areas of estuary. The sex ratio (males/females) was different according to the size classes, being much higher than 1 in the first size classes, showing afterwards, in older individuals a value close to 1. The secondary production (P) estimated for C. maenas was different during all the period, having higher values in droughts years. The ordering diagrams (RDA) showed spatial, temporal and environmental differences of Carcinus maenas in the Mondego estuary. A correlation between Carcinus maenas biological features and the environmental variables and the North-Atlantic Oscillation index (NAO index) was verified through the cumulative sums analysis (CUSUM). The different populations of the green crab on the planet, showed clear differences in the recruitment period, the maximum size of the individuals and the life span. Southern European populations have lower maximum carapace width and a longer recruitment period. With the increase of latitude, populations with larger maximum carapace width and with a shorter recruitment period were observed. The existence of extreme climate events causes leads to an adjustment on the population dynamics of Carcinus maenas. Bigger differences are present during extreme droughts, where due to the low river flow and an increase in the salinity, there will be a more intense recruitment of juveniles, leading to an increase in population density.
FCT
40
Campana, Pete. "Water usage in Athens, Georgia as a result of the 2007 drought event and analysis of future water availability." 2009. http://purl.galileo.usg.edu/uga%5Fetd/campana%5Fpeter%5Fa%5F200905%5Fms.
41
Tsay, Yih-Liang, and 蔡易良. "Analysis and Study on Irrigation Practice for Coping with Drought Event in Shi-Tze-Tou Tsuen Irrigation Area of kaohsiung Irrigation Assocation." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/33219043150518505429.
42
FURIK, Miroslav. "Analýza řešení připravenosti obcí na mimořádnou událost sucho v regionu Jihočeského kraje." Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-320699.
Анотація:
The aim of this diploma thesis is to evaluate the needs and preparedness of municipalities with extended competence of the South Bohemian Region for an extraordinary event of drought. To achieve the stated goal, a search of available literature and foreign sources was carried out, which helped obtain the basic information necessary to understand this issue. A qualitative research method based on a structured interview was used to analyze the needs and readiness of municipalities with extended competence. This research was carried out among the crisis management personnel of municipalities with extended competence in the territory of the South Bohemian Region. Other experts such as those involved in the crisis management department of the South Bohemian Regional Office, the Department of the Environment of Municipalities with Extended Powers or the Fire Brigade of the South Bohemian Region were also questioned. The available documents also examined details of selected aspects that increase the resilience and preparedness of municipalities with extended jurisdiction for drought. These documents examined the extent of involvement of state administration and self-government in drought preparedness issues and the way of implementation in the analyzed documents. Afterwards, the information collected was arranged and evaluated. The research has shown that the preparedness of the municipalities with extended powers for the extraordinary event of drought is insufficient. Documentation dealing with drought issues has not been elaborated for individual administrative districts of municipalities with extended competence and has not been incorporated in the emergency plan of the region or the crisis plan of the municipality with extended competence. Another problem is the insufficient information of municipalities with extended competence on drought episodes in the administrative districts of municipalities with extended competence in the territory of the South Bohemian Region. The research also identified a problem with a low number of drinking water sources and insufficient provision of alternative or emergency drinking water sources.
43
Sikhwari, Thendo. "Variability and long-term trends of climate extremes over the Limpopo, South Africa." Diss., 2019.
Анотація:
MENVSCDepartment of Geography and Geo-Information Sciences
Climate change has a crucial impact on livelihoods, economy, and water resources due to the occurrence of weather and climate extreme events such as floods, droughts and heat waves. Extreme weather has been increasing worldwide, hence the need to understand their nature and trends. The aim of this study was to analyse the spatial variability and long-term trends of climate extremes over the Limpopo in South Africa from 1960 to 2014. Rainfall, temperature, and circulation fields were analysed to understand the extent, nature of climate extremes over the Limpopo. Extreme value theory (EVT) is a powerful method that was also employed in this study to provide statistical models for events rarely observed. R statistical software was used for clustering analysis which has a variety of functions for cluster analysis. Any station whose value is larger than 95th for any day of the season was considered as a widespread extreme event. The results show that the study area is highly vulnerable to extreme events due to its latitudinal location and low altitude. Anomalous cut-off lows, tropical cyclones and tropical storms are the major extreme producing systems affecting the Limpopo province whilst the Botswana High becomes dominant during heat waves and drought. Extreme weather events are common in Limpopo during summertime and often coincide with mature phases of the El Nino Southern Oscillation. In this study, after the suitable model for data was chosen, the interest was in deriving return levels of extreme maximum rainfall. The computed data for return levels predicted that the 5-year return period’s return level is approximately 223.89 mm, which suggests that rainfall of 223.89 mm or more per month should occur at that station or location on the average of once every five years.
NRF
http://hdl.handle.net/11602/1485