Determining the effect of deforestation on sustainable water supply in a semi-arid mountainous watershed by using storm water management model

Abstract

In this study, the effect of deforestation on sustainable water supply in a semi-arid mountainous watershed was determined by using runoff as an indicator of groundwater recharge. Storm water management model (SWMM) was used to simulate deforestation scenarios and effect of rainfall intensity. According to result, runoff amount increases from 1.505 cm3/sec to 2.509 cm3/sec with increase ratio of 66.71%, 1.881 cm3/sec with increase ratio of 24.98% and 1.658 cm3/sec with increase the ratio of 10.17% during 10 mm/day rainfall event in the conversion of forest to urban, agriculture and rangeland scenarios, respectively. It was also determined that rainfall intensity had more effect on runoff than deforestation in the study area. The study clearly shows that deforestation can lead to decrease groundwater recharge, and consequently, decrease in low flow which is important for ecosystem sustainability in especially drought periods are characteristic of Mediterranean region in the watershed.