Study of trend and relationship between meteorological and hydrogeological droughts of Sufi Chai and Mordagh Chai watershed

Abstract

Drought is a natural disaster, which its intensity and frequency of occurrence and the affected area a nd the amount of damage, is more important than other natu ral disasters. In this study, successive periods of meteorological and hydrological drought were invest igated using SPI and SDI index in Sufi Chai and Mor dagh Chai basins in the Southeast of Urmia Lake, and the time delay between the two occurrences was identif ied. Therefore, 10 rain gauges and 7 hydrometric station data was used. Range and area droughts in ArcGIS m edia were plotted according to the mean-square error min imum using methods of the kriging and IDW and also droughts trend was investigated by classic Mann-Ken dall and modified Mann–Kendall droughts methods. The results showed that the occurrence of the two perio ds of severe and long-term meteorological drought h as led to the simultaneous occurrence of hydrological drought in the basins. There is a significant correlation at 99% level between meteorological and hydrological droughts wh ich is stronger for simultaneous occurrence and one month lag time. According to drought zoning maps, the Nor thwest region has more potential in the terms of fr equency and severity of meteorological drought occurrence w hich is important in the water resources management.