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...

Drought is the dominant process of crop loss nationally and within Nebraska. Nearly twothirds of the 18.6 million harvested acres are covered by crop insurance (USDA/RMA, 2003; USDA/NASS, 2003). For the most part, Nebraska’s crop losses range from $50 to 75 million in non-drought years, but the losses approach nearly $200 million in drought years, such as 2000. The past growing season (2002) cr...

of the many climatic events that influence the earth’s environment, drought is perhaps the one that is most linked with desertification. drought is the consequence of a natural reduction in the amount of precipitation received over an extended period, usually a season or more in length. drought monitoring is an essential component of drought risk management. it is normally performed using vario...

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 ...

Drought is a climate phenomenon which might occur in any climate condition and all regions on the earth. Effective drought management depends on the application of appropriate drought indices. Drought indices are variables which are used to detect and characterize drought conditions. In this study, it was tried to predict drought occurrence, based on the standard precipitation index (SPI), usin...

in this paper by using the data related to the monthly precipitation of 13 stations situated in west azerbaijan province of iran in a time period of 34 years, monitoring and forecasting the probability of a drought occurrence is evaluated in next coming months. in this process, first the monthly precipitation amounts for each rainfall station are used in order to calculate the standardized prec...

The standardized precipitation index (SPI) was used to quantify the classification of drought in the Guanzhong Plain, China. The autoregressive integrated moving average (ARIMA) models were developed to fit and forecast the SPI series. Most of the selected ARIMA models are seasonal models (SARIMA). The forecast results show that the forecasting power of the ARIMA models increases with the incre...

introduction: drought is a recurrent feature of climate that caused by deficiency of precipitation over time. due to the rise in water demand and alarming climate change, recent year’s observer much focus on drought and drought conditions. a multiple types of deficits and relevant temporal scales can be achieved through the construction of a joint indicator that draws on information from multip...