Hydrological Drought Analysis of Karkheh River Basin in Iran Using Variable Threshold Level Method

Abstract

Drought is an important phenomenon in recent years which caused a lot of problems for most of areas in Iran. Drought lead to water scarcity for people and this problem becomes one of the important challenges for the country. Karkheh River basin is one of the considerable water resources field in Iran and it is located in west parts of Iran. Current paper tries to take one step ahead toward scientific and practical drought management in Karkheh basin by analyzing hydrological drought. In this paper using daily discharge time series of 13 hydrometric stations which are located in the basin and also applying threshold level method, dry periods were extracted and results were analyzed. Results showed that the most volume and the most duration of drought in threshold level of 70% mostly happened within 1998-2000 and 2006-2008. Also the results of the frequency analysis of drought parameters indicted that for maximum deficit volume series Weibull distribution and Generalized Pareto Distribution (GP) in accordance with 77% of stations and for maximum duration series, GP distribution in accordance with 54% of stations had the most consistency. Based on this consistency, return period of droughts were also computed and the possibility of drought predictions in future was determined.