Analyzing Water Harvesting Potentials in Zoned Areas in Qargha Reservoir Watershed

Abstract

In recent years surface runoff water harvesting is gaining more popularity in arid and semi-arid regions such as Afghanistan due to the increasing demand for scarce water resources. In Paghman District growing season starts in March and ends in October; however, in the latter half from June to October, it hardly rains, which causes crop failure and low productivity. So, collecting and stocking a certain amount of runoff water in the wet season and using it as irrigation water during the latter half of the growing season can reduce water shortage problems. Therefore, this study aimed to analyze water harvesting potentials through identifying suitable water harvesting sites and estimating the potential volume of surface runoff based on the rational method and the sorptivity method in the Qargha Watershed of Paghman District, Afghanistan. In this study, weighted overlay in GIS was used to determine suitable water harvesting sites. Sorptivity method and rational methods were used to estimate the volume of surface runoff. Based on the results of suitability analysis only 27.67% of the land was suitable for water harvesting. The estimated potential volume of surface runoff applied the rational method, and the sorptivity method was at 509.4 m³ and 478.3 m³. Therefore, it was concluded that water harvesting is possible in the study area. However, these estimated potential volumes of surface runoff needed to be calibrated with the observed data.