Feasibility of susceptible areas for rainwater harvesting, based on AHP in GIS environment (a case Study: Khosroabad watershed, Iran)

Providing water to people in arid and semi-arid areas of the world is especially important. Therefore, identification of suitable sites for the construction of rainwater harvesting systems is an important step towards maximizing available water for agriculture and other uses. The purpose of this study is to identify areas susceptible to penetration by rainwater, where rainwater can be collected to restore water resources and enhance vegetation cover, and to be used in different ecosystems of Khosrowabad watershed using hierarchical decision making method based on spatial analysis in a GIS environment. In this research, the factors affecting rainwater penetration and storage in the soil profile of Khosrowabad watershed in the city of Sonqor were identified and entered into the Analytical Hierarchy Process (AHP) process. The selected indices were evaluated using a questionnaire and evaluated by experts’, academics’ and specialists’ opinion by group method during the process of value engineering and were later compared individually and in pairs. Then, their importance coefficients were determined and the paired comparison tables completed. The completed tables were analyzed by the special vector method. In this regard, the weight of seven criteria of vegetation, slope, precipitation, land use, hydrological groups, elevation classes and erosion were calculated using MATLABR2009a software and the required layers were prepared in Arc GIS10.3 environment. Then, using natural breaks in GIS environment, the five levels determined as very appropriate, appropriate, moderate, inappropriate, and unsuitable. From 1855/67 hectares, the total area of ​​the catchment area is 862,600 hectares. The total area of ​​the basin has a suitable and very suitable potential for collecting rainwater and 259.49 hectares of the catchment area with inappropriate and very inappropriate potential for this purpose, reflecting the very high capacity of this basin to store and collect rainwater. The results of this study showed that in addition to the precipitation factor which is one of the main factors, the two factors of gradient and soil characteristics in terms of soil hydrological groups are the more important factors for collecting rainwater compared to the rest of factors and have a more significant impact.