I Identification of Natural Aquifer Recharge Potential Sites in Islamabad by using GIS and RS Based Integrated Techniques

Abstract

Islamabad is the only well-planned city in Pakistan however, groundwater depletion is a serious issue due to the rapid increase in population along with poor water management, urbanization, deforestation, and settlements of many immigrants. The current requirement of water for Islamabad is 220 million gallons per day, while Capital Development Authority (CDA) Islamabad provides up to 70 million gallons per day. Identification of potential sites for natural aquifer recharge is a key factor for groundwater recharge to overcome the water crises. Therefore, this study aims to identify potential sites for natural aquifer recharge by using the analytical hierarchy process (AHP), weighted linear combination (WLC), and fuzzy logic methods. To achieve the required objective, we utilized seven local influencing factors such as soil, slope, water table, population density, LULC, drainage density, and elevations have been utilized in this study. AHP was adopted for the evaluation of the relative importance of the above-mentioned factors and the fuzzy logic for the standardization of selected factors. Finally, the factor maps were combined through AHP-WLC and fuzzy logic method to identify potential sites for natural aquifer recharge (NAR). Two different suitability maps were prepared from both techniques (AHP-WLC & Fuzzy logic) and each of the resulting maps has been classified into five classes; not suitable, less suitable, moderate, suitable, and most suitable. The results revealed that 5% of the whole study area is most suitable for NAR based on AHP-WLC. While 10% of the study area is most suitable, respectively based on fuzzy logic results. Both techniques give satisfactory results however the suitability map from fuzzy logic yields more precise results, therefore we proposed different sites for recharge well to the Capital Development Authority (CDA) based on the results of fuzzy logic. To date, CDA has constructed twelve wells out of eighty as recommended by this study.