Evaluation of Drought Effect on the Ground Water Resource and Agricultural Development in the Behesht Abad Basin Using WEAP Model

Drought is one of the significant problems that has situated in the first rank from the perspective of intensity, duration and damages among the other natural disasters. Some times for compensating this defect, users attack to wards ground waters. if this condition continue, water resource excessively reduce, so The Farsan-Jonaghan and Shalamzar hydrologic units were selected to examine the effect of drought on the Ground Water Resource and agriculture in the Behesht Abad basin(Sub Basin of north karoon Basin), respectively. 30 years records of hydrometery station of Darkesh-Varkesh and Koohe Sookhteh located in the outlet of Jonaghan and Behesht Abad River was used to monitoring of drought effect in the Farsan-Jonaghan and Shalamzar plains, respectively. Normal percentage index was used to determine of wet, normal and dry years. WEAP model as water resources allocation model was utilized to evaluate of agriculture status. The model was calibrated and validated using data for 10 (1995-2004) and 30 (2005-2034) years, respectively. Then, some scenarios were considered. Condition of ground water level and agriculture was examined in the limited extract of an aquifer. The results showed that the highest effect of drought was on the groundwater level of aquifer (in some of dry years the volume of aquifer reduce 30%). In the other scenario, the fluctuation of groundwater level of aquifer was controlled during dry years. In this condition, there was a significant different between the percentages of meeting demands of dry and wet years. The level of normal cultivation with regard to the kind of climate was modeled with consideration of normal demand supply percent in total wet and dry years. Finally, using the results of model, a graph was prepared that it can be used for measuring of the cultivation area changing for each degree of drought.