نتایج جستجو برای: standardized precipitation index spi
تعداد نتایج: 519315 فیلتر نتایج به سال:
The Standardized Precipitation Index (SPI) is the most common index for drought monitoring. Although the calculation of this index is usually done by using the gamma distribution fitting of precipitation data, studies have shown that for accurate monitoring of drought, the optimal distribution of precipitation in each month should be determined. On the other hand, in non-stationary time series,...
Abstract In this research, SPEI (standardized precipitation and evaporation index) was used as an alternative index to SPI to study drought in warm southern coastal regions of Iran. Drought has a multi-scale nature that can be analyzed in time scales via analysis of precipitation and temperature data. Therefore, data were colected from 105 synoptic stations in Iran in 2015; Respective stati...
Abstract The use of artificial neural networks as a tool to forecast droughts in Sri Lanka is presented. Predictions were made using the Standardized Precipitation Index (SPI) as the drought monitoring index. Monthly rainfall recorded at 13 climatological stations covering both the wet and dry zones over a long time period have been used as the input to train and test the neural networks. The a...
the effect of drought indices on hydrostatic variations and qualitative parameters of the zahedan plain's aquifer was investigated. for this purpose, 12-year statistics from observational and piezometry wells in the plain, the drought index of percentage normal )pn), standardized precipitation index )spi(, and 30-year precipitation statistics of zahedan station were used. results revealed ...
تاثیرپذیری خشکسالی از شرایط گوناگون اقلیمی، مانعی برای تعریف روشن و جامعی از آن شده است. برای پایش خشکسالی شاخص‌های گوناگونی در مقیاس‌های متفاوت زمانی ماهانه و سالانه مورد استفاده قرار گرفته است. از محدودیت‌های شاخص‌های رایج همچون شاخص بارش استاندارد شده (SPI)[1] عدم در نظرگرفتن بیلان آب بر پایة مقدار تبخیر و تعرق می‌باشد. شاخص بارش- تبخیر و تعرق استاندارد شده (SPEI)[2] بر پایة بارش و تبخیر و ت...
At present, the Standardized Precipitation Index (SPI) is the most widely used drought index to provide good estimations about the intensity, magnitude and spatial extent of droughts. The main advantage of the SPI in comparison with other indices is the fact that the SPI enables both determination of drought conditions at different time scales and monitoring of different drought types. It is wi...
Drought detecting is a necessary aspect of drought risk management. It is generally performed usingdifferent drought indices that are effectively continuous functions of rainfall and other hydro- meteorologicalvariables. A number of drought indices have been introduced and used in various countries to date. In thecurrent research, four meteorological drought indices including the standardized p...
In this study, the trends of changes of the standardized precipitation index in a 12-month timescale (SPI-12) and seasonal and annual precipitation were investigated in 21 humid and semi-arid stations of Iran during the 1976-2014 time period. After removing the serial correlation of some series, the trend of precipitation and SPI-12 was detected using the Mann-Kendall nonparametric trend test. ...
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