Identifying Potential Areas for Rainwater Harvesting in Saudi Arabia

Arid and semi-arid regions (ASARs), in particular, require adequate management of water resources to fulfill existing demands and ensure sustainability in the future. Rainwater harvesting (RWH) is the practice of collecting and concentrating runoff from rainfall for domestic water supply, agricultural use, and livestock. Rainfall is one of the critical elements of any RWH system, and the amount of rain significantly impacts determining if a particular area is suitable for RWH use. Two categories of selection criteria (biophysical and socio-economic) are used to identify relevant sites, and the technical layout of RWH systems is crucial to their success. The technical design of RWH systems is essential to their performance, and two categories of selection criteria (biophysical and socio-economic) are employed to identify suitable sites. The site's biophysical features determine whether the RWH structures are appropriate in terms of their applicability and use by the stakeholders, and the socio-economic factors determine, among other things, the intended beneficiaries and the fair distribution of resources among the various stakeholders. The primary objective of this study is to evaluate the potential for rainwater harvesting (RWH) and to identify possible RWH locations in Saudi Arabia using geospatial information system (GIS), remote sensing (RS) and multiple criterion decision analysis methods (MCDA). The fuzzy membership tool was used to reclassify or transform the biophysical data for rainfall, slope, curve number, and drainage density to a 0–1 scale based on the suitability of the RWH potential. The Analytic Hierarchy Process (AHP), a multi-criteria decision-making method, was utilized to analyze biophysical factors based on their relative importance and the pairwise comparisons experts proposed to produce the potential RWH map. A ranking matrix for pairwise comparisons of biophysical parameters was developed to demonstrate the relative importance of the parameters after the hierarchy had been formed. After that, the normalized criteria weight vector was calculated by averaging the relative weights of each parameter in relation to each other. As a weighted linear combination of the normalized weight of each criterion and its fuzzy membership, the normalized Rainwater Harvesting Potential Index (RWHPI) was created. It is a dimensionless indicator. RWHPI identifies the Kingdom's high-potential RWH locations. The RWH potential map (i.e., poor, moderate, and good) was produced by integrating the biophysical layers with the corresponding normalized weights using GIS techniques. The normalized Rainwater Harvesting Potential Index (RWHPI) is a dimensionless indicator that was generated as a weighted linear combination of the normalized weight of each criterion and its fuzzy membership. RWHPI identifies areas with a high potential for RWH within the Kingdom. The RWH potential map (i.e., poor, moderate, and good) was created by combining the biophysical layers with the accompanying normalized weights using GIS methods.