Global warming has resulted in increasingly frequent and severe drought and/or precipitation events. Severe drought limits crop water availability and impacts agricultural productivity and socioeconomic development. To quantify drought-induced yield loss during the main crop stages in Liaoning province, China, aspects of drought episodes (magnitude, duration, and frequency) were investigated du...

abstract spi is based on fitting a gamma distribution to precipitation amounts in selected periods. based on current research, the gamma distribution may not be fitted to annual precipitation of some regions. in order to evaluate this subject, annual precipitation have been used during 1958- 2007 at 11 synoptic stations in iran. in first step, values of spi and frequency of different classes of...

In this study, drought in Portugal was assessed using 74 time series of Standardized Precipitation Index (SPI) with a 12-month timescale and 66 years length. A clustering analysis on the SPI Principal Components loadings was performed in order to find regions where SPI drought characteristics are similar. A Fourier analysis was then applied to the SPI time series considering one SPI value per y...

regional vegetation plays an important role in modeling ecosystem changes and conservation. meteorological drought indices which are directly obtained from such meteorological data as precipitation can't be useful in drought monitoring if those data are absence. therefore, remote sensing techniques may provide an efficient technique for drought monitoring. in this study, the values of norm...

the aim of this research is to analyze the performance of 8 drought’s index in isfahan, kerman and yazd province and choose the best index. for this purpose, used monthly and yearly rainfall data in the period of 30 years (1985-2014) and also used 8 drought indexes in 20 meteorological stations of central iran which the accuracy of each index in determining drought is examined. also zoning in 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 ...