Добірка наукової літератури з теми "Rainfall percentile"
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Статті в журналах з теми "Rainfall percentile"
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Shrestha, Sushban, Xing Fang, and Wesley C. Zech. "What Should Be the 95th Percentile Rainfall Event Depths?" Journal of Irrigation and Drainage Engineering 140, no. 1 (January 2014): 06013002. http://dx.doi.org/10.1061/(asce)ir.1943-4774.0000658.
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Thangjai, Warisa, Sa-Aat Niwitpong, and Suparat Niwitpong. "Estimation of common percentile of rainfall datasets in Thailand using delta-lognormal distributions." PeerJ 10 (December 7, 2022): e14498. http://dx.doi.org/10.7717/peerj.14498.
Повний текст джерелаАнотація:
Weighted percentiles in many areas can be used to investigate the overall trend in a particular context. In this article, the confidence intervals for the common percentile are constructed to estimate rainfall in Thailand. The confidence interval for the common percentile help to indicate intensity of rainfall. Herein, four new approaches for estimating confidence intervals for the common percentile of several delta-lognormal distributions are presented: the fiducial generalized confidence interval, the adjusted method of variance estimates recovery, and two Bayesian approaches using fiducial quantity and approximate fiducial distribution. The Monte Carlo simulation was used to evaluate the coverage probabilities and average lengths via the R statistical program. The proposed confidence intervals are compared in terms of their coverage probabilities and average lengths, and the results of a comparative study based on these metrics indicate that one of the Bayesian confidence intervals is better than the others. The efficacies of the approaches are also illustrated by applying them to daily rainfall datasets from various regions in Thailand.
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Cao, Fuqiang, Tao Gao, Li Dan, Lian Xie, and Xiang Gong. "Variability of Summer Precipitation Events Associated with Tropical Cyclones over Mid-Lower Reaches of Yangtze River Basin: Role of the El Niño–Southern Oscillation." Atmosphere 10, no. 5 (May 9, 2019): 256. http://dx.doi.org/10.3390/atmos10050256.
Повний текст джерелаАнотація:
Based on tropical cyclone (TC) track data and gridded observational rainfall data of CN05.1 during the period of 1961 to 2014, we examine the contribution of TCs on three metrics of summertime rainfall regimes and identify the connection between TC-induced precipitation events and El Niño–Southern Oscillation (ENSO) in middle–lower reaches of Yangtze River Basin (MLYRB). At the regional scale, TCs are responsible for approximately 14.4%, 12.5%, and 6.9% of rainfall events for normal, 75th, and 95th percentile precipitation cases, respectively. There is no evidence of significant long-term trends of the three type events linked with TCs, while their interdecadal variability is remarkable. Fractionally, larger proportions of TC-induced events occur along southeast coastal regions of MLYRB for normal rainfall events, and they are recorded over southwest and central-east MLYRB for 95th percentile cases. Moreover, a larger contribution of 95th percentile precipitation events to summer total rainfall is found than that for 75th percentile cases, suggesting that TCs may exert stronger impacts on the upper tail of summertime precipitation distribution across MLYRB. The TC-induced normal rainfall events tend to occur more frequency over central-west MLYRB during negative phase of ENSO in summer. However, the higher likelihood of TC-induced rainfall for three defined metrics are found over the majority of areas over MLYRB during negative ENSO phase in spring. In preceding winter, La Niña episode plays a crucial role in controlling the frequency of both normal and 75th percentile precipitation events.
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Ramezani Ziarani, Maryam, Bodo Bookhagen, Torsten Schmidt, Jens Wickert, Alejandro de la Torre, and Rodrigo Hierro. "Using Convective Available Potential Energy (CAPE) and Dew-Point Temperature to Characterize Rainfall-Extreme Events in the South-Central Andes." Atmosphere 10, no. 7 (July 8, 2019): 379. http://dx.doi.org/10.3390/atmos10070379.
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The interactions between atmosphere and steep topography in the eastern south–central Andes result in complex relations with inhomogenous rainfall distributions. The atmospheric conditions leading to deep convection and extreme rainfall and their spatial patterns—both at the valley and mountain-belt scales—are not well understood. In this study, we aim to identify the dominant atmospheric conditions and their spatial variability by analyzing the convective available potential energy (CAPE) and dew-point temperature ( T d ). We explain the crucial effect of temperature on extreme rainfall generation along the steep climatic and topographic gradients in the NW Argentine Andes stretching from the low-elevation eastern foreland to the high-elevation central Andean Plateau in the west. Our analysis relies on version 2.0 of the ECMWF’s (European Centre for Medium-Range Weather Forecasts) Re-Analysis (ERA-interim) data and TRMM (Tropical Rainfall Measuring Mission) data. We make the following key observations: First, we observe distinctive gradients along and across strike of the Andes in dew-point temperature and CAPE that both control rainfall distributions. Second, we identify a nonlinear correlation between rainfall and a combination of dew-point temperature and CAPE through a multivariable regression analysis. The correlation changes in space along the climatic and topographic gradients and helps to explain controlling factors for extreme-rainfall generation. Third, we observe more contribution (or higher importance) of T d in the tropical low-elevation foreland and intermediate-elevation areas as compared to the high-elevation central Andean Plateau for 90th percentile rainfall. In contrast, we observe a higher contribution of CAPE in the intermediate-elevation area between low and high elevation, especially in the transition zone between the tropical and subtropical areas for the 90th percentile rainfall. Fourth, we find that the parameters of the multivariable regression using CAPE and T d can explain rainfall with higher statistical significance for the 90th percentile compared to lower rainfall percentiles. Based on our results, the spatial pattern of rainfall-extreme events during the past ∼16 years can be described by a combination of dew-point temperature and CAPE in the south–central Andes.
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Krishnamurthy, Chandra Kiran B., Upmanu Lall, and Hyun-Han Kwon. "Changing Frequency and Intensity of Rainfall Extremes over India from 1951 to 2003." Journal of Climate 22, no. 18 (September 15, 2009): 4737–46. http://dx.doi.org/10.1175/2009jcli2896.1.
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Abstract Using a 1951–2003 gridded daily rainfall dataset for India, the authors assess trends in the intensity and frequency of exceedance of thresholds derived from the 90th and the 99th percentile of daily rainfall. A nonparametric method is used to test for monotonic trends at each location. A field significance test is also applied at the national level to assess whether the individual trends identified could occur by chance in an analysis of the large number of time series analyzed. Statistically significant increasing trends in extremes of rainfall are identified over many parts of India, consistent with the indications from climate change models and the hypothesis that the hydrological cycle will intensify as the planet warms. Specifically, for the exceedance of the 99th percentile of daily rainfall, all locations where a significant increasing trend in frequency of exceedance is identified also exhibit a significant trend in rainfall intensity. However, extreme precipitation frequency over many parts of India also appears to exhibit a decreasing trend, especially for the exceedance of the 90th percentile of daily rainfall. Predominantly increasing trends in the intensity of extreme rainfall are observed for both exceedance thresholds.
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Niyogi, Dev, Ming Lei, Chandra Kishtawal, Paul Schmid, and Marshall Shepherd. "Urbanization Impacts on the Summer Heavy Rainfall Climatology over the Eastern United States." Earth Interactions 21, no. 5 (June 1, 2017): 1–17. http://dx.doi.org/10.1175/ei-d-15-0045.1.
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Abstract The relationship between rainfall characteristics and urbanization over the eastern United States was examined by analyzing four datasets: daily rainfall in 4593 surface stations over the last 50 years (1958–2008), a high-resolution gridded rainfall product, reanalysis wind data, and a proxy for urban land use (gridded human population data). Results indicate that summer monthly rainfall amounts show an increasing trend in urbanized regions. The frequency of heavy rainfall events has a potential positive bias toward urbanized regions. Most notably, consistent with case studies for individual cities, the climatology of rainfall amounts downwind of urban–rural boundaries shows a significant increasing trend. Analysis of heavy (90th percentile) and extreme (99.5th percentile) rainfall events indicated decreasing trends of heavy rainfall events and a possible increasing trend for extreme rainfall event frequency over urban areas. Results indicate that the urbanization impact was more pronounced in the northeastern and midwestern United States with an increase in rainfall amounts. In contrast, the southeastern United States showed a slight decrease in rainfall amounts and heavy rainfall event frequencies. Results suggest that the urbanization signature is becoming detectable in rainfall climatology as an anthropogenic influence affecting regional precipitation; however, extracting this signature is not straightforward and requires eliminating other dynamical confounding feedbacks.
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Widi, Herlia, Dea Nisa Rahma Lani, and Faridatul Hasanah. "Determining Agricultural Premium Insurance in Malang City using Black Scholes Model." International Journal of Global Operations Research 2, no. 2 (May 7, 2021): 80–87. http://dx.doi.org/10.47194/ijgor.v2i2.81.
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This study examines the determination of rainfall-based agricultural insurance premium prices using the Black-Scholes model. The Black-Scholes model was originally used to determine the price of European-type options. The research method used is a literature study with secondary data collection. The data used in this study are rainfall data and rice production results in the city of Malang from 2015 to 2020. Based on the results and discussion, rainfall which is strongly correlated with rice production results is in quarter 2. The premium results obtained are different according to the desired percentile. In addition to percentiles, taking R_0 also affects the premium price. When R_0=322, the premium price tends to be cheaper than R_0=271.
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Dave, Hiren, and James M. E. "Characteristics of intense rainfall over Gujarat State (India) based on percentile criteria." Hydrological Sciences Journal 62, no. 12 (August 18, 2017): 2035–48. http://dx.doi.org/10.1080/02626667.2017.1357818.
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Zahiri, Eric-Pascal, Modeste Kacou, Marielle Gosset, and Sahouarizié Adama Ouattara. "Modeling the Interdependence Structure between Rain and Radar Variables Using Copulas: Applications to Heavy Rainfall Estimation by Weather Radar." Atmosphere 13, no. 8 (August 15, 2022): 1298. http://dx.doi.org/10.3390/atmos13081298.
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In radar quantitative precipitation estimates (QPE), the progressive evolution of rainfall algorithms has been guided by attempts to reduce the uncertainties in rainfall retrieval. However, because most of the algorithms are based on the linear dependence between radar and rain variables and designed for rain rates ranging from light to moderate rainfall, they result in misleading estimations of intense or strong rainfall rates. In this paper, based on extensive data gathered during the AMMA and Megha-Tropiques data campaigns, we provided a way to improve the estimation of intense rainfall rates from radar measurements. To this end, we designed a formulation of the QPE algorithm that accounts for the co-dependency between radar observables and rainfall rate using copula simulation synthetic datasets and using the quantile regression features for a more complete picture of covariate effects. The results show a clear improvement in heavy rainfall retrieval from radar data using copula-based R(KDP) algorithms derived from a realistic simulated dataset. For a better performance, Gaussian copula-derived algorithms require a 0.8 percentile distribution to be considered. Conversely, lower percentiles are better for Student’s, Gumbel and HRT copula estimators when retrieving heavy rainfall rates (R > 30). This highlights the need to investigate the entire conditional distribution to determine the performance of radar rainfall estimators.
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Liu, Tao, Luke A. McGuire, Nina Oakley, and Forest Cannon. "Temporal changes in rainfall intensity–duration thresholds for post-wildfire flash floods in southern California." Natural Hazards and Earth System Sciences 22, no. 2 (February 10, 2022): 361–76. http://dx.doi.org/10.5194/nhess-22-361-2022.
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Abstract. Rainfall intensity–duration (ID) thresholds are commonly used to assess flash flood potential downstream of burned watersheds. High-intensity and/or long-duration rainfall is required to generate flash floods as landscapes recover from fire, but there is little guidance on how thresholds change as a function of time since fire. Here, we force a hydrological model with radar-derived precipitation to estimate ID thresholds for post-fire flash floods in a 41.5 km2 watershed in southern California, USA. Prior work in this study area constrains temporal changes in hydrological model parameters, allowing us to estimate temporal changes in ID thresholds. The results indicate that ID thresholds increase by more than a factor of 2 from post-fire year 1 to post-fire year 5. Thresholds based on averaging rainfall intensity over durations of 15–60 min perform better than those that average rainfall intensity over shorter time intervals. Moreover, thresholds based on the 75th percentile of radar-derived rainfall intensity over the watershed perform better than thresholds based on the 25th or 50th percentile of rainfall intensity. Results demonstrate how hydrological models can be used to estimate changes in ID thresholds following disturbance and provide guidance on the rainfall metrics that are best suited for predicting post-fire flash floods.
Дисертації з теми "Rainfall percentile"
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Biswas, Falguni. "Hydrology of the upper Hunter catchment." Phd thesis, 2010. http://hdl.handle.net/1885/8760.
Повний текст джерелаАнотація:
One of the ten objectives of the 2004 Australian National Water Initiative is to manage surface and groundwater as a single resource. In order to do that it is necessary to understand the interactions between surface and groundwater, as well as the impacts of water abstraction, land use change and climate variability. In Australia, not just the quantity of water, but also its quality and particularly its salinity are critically important. Some of the difficulties facing agencies in managing surface and groundwater as a single resource are the extreme variability of climate in Australia, the lack of long-term streamflow and groundwater level data sets and the very limited temporal records on water quality.
This thesis presents a study of surface and groundwater interaction and salinity in a selected catchment in the Hunter Valley in mid New South Wales, eastern Australia, where data records are limited and incomplete. The hypotheses tested in this work are that (1) salinity discharge in the Hunter is largely determined by mineral weathering and deep groundwater inflows and (2) a simple parameter-efficient coupled surface and groundwater model can accurately predict groundwater and streamflow behaviour over monthly time scale and is useful in determining surface-groundwater interactions.<....>
Частини книг з теми "Rainfall percentile"
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Hapuarachchi, H. A. S. U., and Sarath Premalal. "Identification of Extreme Rainfall Events for the Period 1970–2019 in Sri Lanka Using Percentile-Based Analysis and Its Projections for 2100 for the Emission Scenarios of RCP 4.5 and 8.5." In Multi-Hazard Early Warning and Disaster Risks, 417–27. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-73003-1_28.
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Shaharudin, Shazlyn Milleana, and Norhaiza Ahmad. "Choice of Cumulative Percentage in Principal Component Analysis for Regionalization of Peninsular Malaysia Based on the Rainfall Amount." In Communications in Computer and Information Science, 216–24. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-6502-6_19.
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Hussain, Manzoor, Ljupcho Jankuloski, M. Habib-ur-Rahman, Massoud Malek, Md Kamrul Islam, M. Reza Raheemi, Jawdat Dana, et al. "Improving sustainable cotton production through enhanced resilience to climate change using mutation breeding." In Mutation breeding, genetic diversity and crop adaptation to climate change, 145–56. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789249095.0015.
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Abstract Cotton, being a leading commercial fibre crop, is grown on 20.5 million hectares in three major cotton-producing countries: China, India and Pakistan. Wide differences in yield per hectare exist among these countries and these are being aggravated by changing climate conditions, i.e. higher temperatures and significant seasonal and regional fluctuation in rainfall. Pakistan is one of the countries most affected by climate change. The disastrous effects of extreme periods of heat stress in cotton were very prominent in Pakistan during the growing seasons 2013-2014 (40-50% fruit abortion) and 2016-2017 (33% shortfall), which posed an alarming threat to the cotton-based economy of Pakistan. Poor resilience of the most commonly grown cotton varieties against extreme periods of heat stress are considered to be major factors for this drastic downfall in cotton production in Pakistan. Using the approach of induced mutation breeding, the Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan, has demonstrated its capabilities in developing cotton mutants that can tolerate the changed climatic conditions and sustain high yields under contrasting environments. The results of studies on the phenological and physiological traits conferring heat tolerance are presented here for thermo-tolerant cotton mutants (NIAB-878, NIAB-545, NIAB-1048, NIAB-444, NIAB-1089, NIAB-1064, NIAB-1042) relative to FH-142 and FH-Lalazar. NIAB-878 excelled in heat tolerance by maintaining the highest anther dehiscence (82%) and minimum cell injury percentage (39%) along with maximum stomatal conductance (27.7 mmol CO2/m2/s), transpiration rate (6.89 μmol H2O/m2/s), net photosynthetic rate (44.6 mmol CO2/m2/s) and physiological water use efficiency (6.81 mmol CO2/μmol H2O) under the prevailing high temperatures.
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Waqas, Muhammad, Muhammad Saifullah, Sarfraz Hashim, Mohsin Khan, and Sher Muhammad. "Evaluating the Performance of Different Artificial Intelligence Techniques for Forecasting: Rainfall and Runoff Prospective." In Weather Forecasting [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98280.
Повний текст джерелаАнотація:
The forecasting plays key role for the water resources planning. Most suitable technique is Artificial intelligence techniques (AITs) for different parameters of weather forecasting and generated runoff. The study compared AITs (RBF-SVM and M5 model tree) to understand the rainfall runoff process in Jhelum River Basin, Pakistan. The rainfall and runoff of Jhelum river used from 1981 to 2012. The Different rainfall and runoff dataset combinations were used to train and test AITs. The data record for the period 1981–2001 used for training and then testing. After training and testing, modeled runoff and observed data was evaluated using R2, NRMSE, COE and MSE. During the training, the dataset C2 and C3 were found to be 0.71 for both datasets using M5 model. Similar results were found for dataset of C3 using RBF-SVM. Over all, C3 and C7 were performed best among all the dataset. The M5 model tree was performed better than other applied techniques. GEP has also exhibited good results to understand rainfall runoff process. The RBF-SVM performed less accurate as compare to other applied techniques. Flow duration curve (FDCs) were used to compare the modeled and observed dataset of Jhelum River basin. For High flow and medium high flows, GEP exhibited well. M5 model tree displayed the better results for medium low and low percentile flows. RBF-SVM exhibited better for low percentile flows. GEP were found the accurate and highly efficient DDM among the AITs applied techniques. This study will help understand the complex rainfall runoff process, which is stochastic process. Weather forecasting play key role in water resources management and planning.
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"Appendix C Monthly Rainfall and its Percentage of the Annual Rainfall." In Hydrology of the Nile Basin, 489–508. Elsevier, 1985. http://dx.doi.org/10.1016/s0167-5648(08)70772-x.
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Bechara, Joseph, and George Mitri. "Assessment of forest fire risk perception at the fireshed level." In Advances in Forest Fire Research 2022, 1005–9. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_152.
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The concept of fire regime is crucial for understanding how wildfires and their effects vary across space and time. We differentiate fire regimes within a regional-sized study area in central Portugal, and then investigate the degree to which their differences are influenced by a set of biophysical drivers. Using civil parishes as units of analysis, we employ three complementary parameters to describe the fire regime over a reference period of 44 years (1975-2018): cumulative percentage of parish area burned, Gini concentration index of burned area over time, and area-weighted total number of wildfires. Cluster analysis is used to aggregate parishes into groups based on similarities regarding these parameters. A classification tree model is then employed to assess the relative capacity of each driver to differentiate between groups of parishes with similar fire regime. Drivers included slope, summer temperature and spring rainfall, land use/land cover (LULC) type and patch fragmentation, and net primary productivity. Results allowed to distinguish four types of fire regime and show that these can be significantly differentiated by the biophysical drivers, of which LULC, slope and spring rainfall are the most important. Among LULC classes, shrubland and herbaceous vegetation play the foremost role, followed by agriculture. Our results highlight the importance of vegetation type, availability, and rate of regeneration, as well as that of topography, in influencing fire regimes in the study area, while suggesting that other drivers, likely of a social nature, should also be taken into account.
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González-Villela, Rebeca, Alfonso Banderas Tarabay, and Marco Mijangos Carro. "Water Availability for the Environmental Flow in Two Rivers of Mexico under Climate Change." In River Basin Management - Under a Changing Climate [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.104881.
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Adaptation to climate change requires, among others, the modification of river flow regimes to account for the change in household, agricultural, industry, and energy water consumption as well as their short/medium/long-term socioeconomic impact. In this study, the comparative analysis of the variation of the precipitation in relation to the availability of water in the Yautepec and Cuautla rivers in Morelos, Mexico, for the previous period and subsequent period is carried out, to determine the change in the availability of water in the ecosystem. In winter (February), an increase in rainfall on the Yautepec and Cuautla River was observed, where annual seasonal agriculture and Pine and Oyamel forest are the characteristic vegetation. In autumn (October), a decrease in precipitation takes place. The flows in some regions do not coincide with the increase in the percentage of precipitation (Oaxtepec and Las Estacas Stations) and point out the synergistic effect of the human use of the water resource and the effects of climate change. On Ticumán Station, the depletion of the flow only can be associated with the use of the resource by human influence. The modifications caused by alteration of a river’s flow regime and climatic change must be studied through comparative multidisciplinary studies that give to decision-makers the design of environmental flows.
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Gupta, Avijit. "Accelerated Erosion and Sedimentation in Southeast Asia." In The Physical Geography of Southeast Asia. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780199248025.003.0026.
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Periodic attempts to plot global distribution of erosion and sedimentation usually attribute most of Southeast Asia with a very high sediment yield (Milliman and Meade 1983). The erosion rates and sediment yield figures are especially high for maritime Southeast Asia. Milliman and Syvitski (1992), for example, listed 3000 t km−2 yr−1 for the archipelagos and peninsulas of Southeast Asia. They provided a number of natural explanations for the high erosion rate: location near active plate margins, pyroclastic eruptions, steep slopes, and mass movements. This is also a region with considerable annual rainfall, a very substantial percentage of which tends to be concentrated in a few months and falls with high intensity. Part of Southeast Asia (the Philippines, Viet Nam, Timor) is visited by tropical cyclones with heavy, intense rainfall and possible associated wind damage to existing vegetation. The fans at the foot of slopes, the large volume of sediment stored in the channel and floodplain of the rivers, and the size of deltas all indicate a high rate of erosion and episodic sediment transfer. This episodic erosion and sediment transfer used to be controlled for most of the region by the thick cover of vegetation that once masked the slopes. When vegetation is removed soil and regolith de-structured, and natural slopes altered, the erosion rates and sediment yield reach high figures. Parts of Southeast Asia display striking anthropogenic alteration of the landscape, although the resulting accelerated erosion may be only temporary, operating on a scale of several years. Over time the affected zones shift, and slugs of sediment continue to arrive in a river but from different parts of its drainage basin. The combination of anthropogenic alteration and fragile landforms may give rise to very high local yields. Sediment yields of more than 15 000 t km−2 yr−1 have been estimated from such areas (Ruslan and Menam, cited in Lal 1987). This is undoubtedly towards the upper extreme, but current destruction of the vegetation cover due to deforestation, expansion of agriculture, mining, urbanization, and implementation of large-scale resettlement schemes has increased the sediment yield from < 102 to > 103 t km−2 yr−1.
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Alfredo Rodríguez-Pineda, José, and Lorrain Giddings. "Agricultural Drought in North-Central Mexico." In Monitoring and Predicting Agricultural Drought. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195162349.003.0018.
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Drought is the most significant natural phenomenon that affects the agriculture of northern Mexico. The more drought-prone areas in Mexico fall in the northern half of the country, in the states of Chihuahua, Coahuila, Durango, Zacatecas, and Aguascalientes (figure 10.1). The north-central states form part of the Altiplanicie Mexicana and account for 30.7% of the national territory of 1,959,248 km2. This area is characterized by dry and semidry climates (Garcia, 1981) and recurrent drought periods. The climate of Mexico varies from very dry to subhumid. Very dry climate covers 21%, dry climate covers 28%, and temperate subhumid and hot subhumid climates prevail in 21% and 23% of the national territory, respectively. About 20 years ago, almost 75% of Mexico’s agricultural land was rainfed, and only 25% irrigated (Toledo et al., 1985), making the ratio of rainfed to irrigated area equal to 3. However, for the northern states this ratio was 3.5 during the 1990–98 period (table 10.1). Because of higher percentage of rain-fed agriculture, drought is a common phenomenon in this region, which has turned thousands of hectares of land into desert. Though the government has built dams, reservoirs, and other irrigation systems to alleviate drought effects, rain-fed agriculture (or dryland farming) remains the major form of cultivation in Mexico. In Mexico, there is no standard definition for agricultural drought. However, the Comisión Nacional del Agua (CNA; i.e., National Water Commission), which is a federal agency responsible for making water policies, has coined its own definition for drought. This agency determines whether a particular region has been affected by drought, by studying rainfall records collected from the national climatic network. The national climatic network is spread throughout the country and is managed by the Servicio Meteorológico Nacional (SMN; i.e., National Meteorological Services). The CNA determines, for a municipal region, if the rainfall is equal to or less than one standard deviation from the long-term mean over a time period of two or more consecutive months. If it is, then the secretary of state declares drought for the region.
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Maun, M. Anwar. "The sand dune environment." In The Biology of Coastal Sand Dunes. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780198570356.003.0007.
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The micro-environmental conditions of different soil habitats are influenced by prevailing vegetation, aspect, soil texture, soil colour and other variables that influence the incoming and outgoing solar energy. The variability is especially pronounced in sand dunes because of shifting substrate, burial by sand, bare areas among plants, porous nature of sand and little or no organic matter, especially during the early stages of dune development. Even within a dune system there is disparity in radiative heating of different habitats that is manifested as variation in micro-environmental factors such as relative humidity, temperature, light, moisture content and wind turbulence. The major factor affecting these changes is the establishment of vegetation that stabilizes the surface, adds humus, develops shade, aids in the development of soil structure and reduces the severity of drought on the soil surface. The system changes from an open desert-like sandy substrate on the beach to a mature, well-developed soil system with luxuriant plant communities. The principal topics discussed in this chapter include accounts of micro-environmental factors of coastal sand dunes that influence the growth and reproduction of colonizing species. The water content of the substratum in sandy soils is one of the most important limiting factors in plant growth. Sandy soils have high porosity and after a rain most of the water is drained away from the habitat because of the large interstitial spaces between soil particles and the low capacity of sand to retain water. Evaporation in open dune systems also removes substantial quantities of water. Lichter (1998) showed that evaporation was greater on non-forested dune ridges than on forested areas and the rate of soil drying was influenced by soil depth and dune location. After 3 days of a heavy rainfall there was a drastic decrease in the percentage of moisture (67–80%) at 0–5 cm levels in open habitats compared to only 30–36% in the forested dune ridges. The same measurements at 10–15 cm depths showed much lower reduction in the percentage of moisture. In the swale (slack) even though the evaporative demand was the same, there was actually an increase in moisture because of seepage from the dune ridges.
Тези доповідей конференцій з теми "Rainfall percentile"
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Shrestha, Sushban, Xing Fang, and Junqi Li. "Mapping the 95th Percentile Daily Rainfall in the Contiguous U.S." In World Environmental and Water Resources Congress 2013. Reston, VA: American Society of Civil Engineers, 2013. http://dx.doi.org/10.1061/9780784412947.021.
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Phumkokrux, N., S. Sirito, S. Klaynadda, and P. Sonsri. "AGRICULTURAL DROUGHT INVESTIGATION OF NORTHERN THAILAND USING GENERALIZED MONSOON INDEX." In The 5th International Conference on Climate Change 2021 – (ICCC 2021). The International Institute of Knowledge Management, 2021. http://dx.doi.org/10.17501/2513258x.2021.5102.
Повний текст джерелаАнотація:
This research aims to study a change of rainfall and indicate levels of agricultural drought in the Southwest monsoon period of the northern region of Thailand by using the GMI. The rainfall data from June to September of the year 1987 to 2019 were collected from 21 meteorological stations over the northern region of Thailand. The data were used to create the maps of agricultural drought levels and to analyze the distribution of agricultural drought on the study period. Then, the distribution of total rainfall maps of each month and the trend of rainfall over the past 33 years were examined. The results showed that agricultural drought in Northern Thailand had no exact pattern. However, there was a drought impact on crops level in the lower part of Northern Thailand at the end of the Southwest monsoon period in 2019 with the GMI percentile score average (GMIpctsw) of 22.82 %. Furthermore, the severe drought impact and possible crop failure level were observed in the upper part of Northern Thailand in the same period. Moreover, the total rainfall sharply increased from June to August then decreased in September. The trend of total rainfall of the Southwest monsoon period (June to September) fluctuates along the study period with average value of 796.67 millimeter. Keywords: Agricultural drought; Drought in Thailand; Generalized Monsoon Index; Rainfall change
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Niksic, Matej, and Jernej Cervek. "Changed precipitation patterns and the need for a novel approach to building plot planning." In 55th ISOCARP World Planning Congress, Beyond Metropolis, Jakarta-Bogor, Indonesia. ISOCARP, 2019. http://dx.doi.org/10.47472/ywza7963.
Повний текст джерелаАнотація:
The events related to climate change are recently challenging the Slovenian urban planning. One of them are the floods in urbanised areas that call for a radically new approaches to how the urban built structure is organised and managed. The continental (and largest) part of Slovenia has a subalpine climate which has been traditionally characterised by a moderate precipitation throughout the year. This is now being changed as the larger amounts of water fall on the ground in a shorter period. As the current urban structure is not shaped in accordance with these new circumstances, parts of the cities are getting flooded more often. Some mitigation measures have been implemented, however to address the issue comprehensively new urban planning approaches are needed too. The paper will present one of the tools that has been developed within the endeavours of the national Ministry of Spatial Planning to reform the urban planning system to better reflect the changes posed by the climate change. It is related to the urban design criteria for building plots planning. To allow the rainfall to penetrate the soil as soon as the precipitation reaches the ground, new measures in organisation of the building plots will be provided. The current system defines the percentage of the built-up area within the plot but does not consider the permitted percentage of the paved open spaces (which do not allow the water to penetrate into the grounds), therefor it will be supplemented by the new measures based on the ability of the plots to allow the penetration of the water. The paper firstly presents the current system of building plots regulation within the Slovenian planning system. It then reports the results of the extensive analyses that focused on the existing characteristics of building plots for different building typologies across the country (housing, production, trade, public services) with the aim to map the state of the art in terms of the potential of the existing building plots to allow the water to flow into the grounds. The third part explains the methodological framework for the new approach to the building plots regulation. The last part presents the newly proposed approach and relates it to other urban design tools that need to support the implementation in practice. The concluding section relates the lessons learnt in Slovenian case to the similar situations elsewhere and stress the responsibilities that the urban planning and design have in providing future urban environments that will ensure the environmentally just living conditions for all.