Investigating the temporal and spatial distribution of drought in Iran based on the standardized precipitation index

Authors

1 Dept of water Engineering

2 Dept. water Engineering, college of Agriculture BASU, Hamedan, Iran

3 Department of Faculty Agriculture University of Malayer

Abstract

Abstract
Drought is result of climate change and specific principle decrease relation to longterm mean margin.for local & time drought variation in disparate weather climate in Iran, nomination vector this variation can in water management and that designation to control variation aspects, these have mater role. In this study the drought variation trend using non-parametric Mann-Kendall in 28 synoptic stations from 1981 to 2010 were studied. Also local dispense survey with earth statistics in ArcGIS9.3 software accomplish. The results of trending drought using Standardized Precipitation Index (SPI) represent the different behavior of drought index in different climates. The results of SPI showed that the majority of climates surveyed have experienced annual drought period. The occurrence of droughts, dry climate with cool winter and hot sammer of the highest annual drought was observed. As this climate drought years mean occurrence percent 20.55 percent was observed. Mann-Kendall test results Standardized Precipitation Index (SPI) also Represents that in the 3 seasons, spring, fall, winter and annual scale significant trend increase. The most trend drought significant increase was observed in Sanandaj. Surveyed local dispense observed in annual scale The most drought in south-east of country was increase was observed. In seasons scale, drought local dispense was heterogeneous. But in winter season drought local dispense explanatory was normal drought pitch in country.

Keywords