Determining the Potential of Rain Water Harvesting Based on Geomorphological Factors and Analytic Hierarchy Process (Kalat Watershed, Khorasan Razavi Province)

In this research, a method is proposed to identify and determine rainwater harvesting potential in a watershed based on geomorphological factors through integrating Geographical Information System (GIS) and Analytical Hierarchy Process (AHP). For this purpose, land use, land cover, topography, geology, soil, vegetation, and soil permeability factors were considered the as main geomorphological factors in the Kalat watershed of Gonabad and the corresponding data layers were obtained. Then, weights of the criteria and their classes were calculated using AHP and the results were applied to the existing layers, creating a rainwater harvesting potential map. The results showed that hydrological soil group had the most relative importance for rainwater harvesting potential (0.444). Soil hydrological groups are determined based on soil texture and permeability. Therefore, soil texture and permeability can be considered as the most relatively important factors for rainwater harvesting. In this study, 56.2% of the watershed had medium potential and 16.5% had a high and very high potential for runoff generation. The results showed that the analytical hierarchy process can be used as a method to qualitatively assess  rainwater harvesting potential at the watershed scale.