Abstract:
Immense urbanization due to increase in population in the twin cities of Rawalpindi and Islamabad (Pakistan) has led to an extensive deforestation, depletion in groundwater, increase in flood peaks in Lai Nullah catchment. A compile approach which is needed to cope all these issues one way or the other is rainwater harvesting (RWH). In the present study, RWH potential zones were classified using integrated Remote Sensing and GIS approach following Multi-Criteria Analysis (MCA) based on Analytical Hierarchy Process (AHP) & Fuzzy Analytical Hierarchy Process (FAHP) for a counter verification of one result set through the other. A subjective judgmental approach was used through expert’s judgment using pairwise comparison matrix in both the processes to compute relative importance of one criterion over the other. Five bio-physical criteria were selected namely Rainfall, Slope, Drainage density, Land Use Land Cover (LULC) & Soil texture for pairwise comparison. Spatial analysis of the selected parameters carried out in GIS environment led to the production of criterion’s maps. The input criterion’s maps with influence weights allocation in the spatial analyst tool weighted overlay entailed the production of AHP and FAHP potential site maps in ArcMap 10.5. A 4 % increase in good potential zone with the same decrease in moderate zone were observed in FAHP potential sites map compared to AHP potential sites Map of RWH. The excellent and good classes covered a range of 56-62% in both the RWH potential sites maps. Final suitability maps for the construction of RWH structures was assessed referring to Integrated Mission for Sustainable Development (IMSD) guidelines developed by the National Remote Sensing Agency, Department of Space, Govt. of India in 1995. Final suitability maps with located 40 sites of percolation tanks and 12 sites of check dams were identified. Detailed validation of suitable sites was carried out through ground truthing data of LULC and stream order map of the watershed with further justification through AHP and FAHP potential sites maps. Final suitability maps show the structure location on 2nd and 3rd stream order, lies in Agricultural and Forest land use classes, and located in excellent and good classes of potential site maps. Final suitability maps can be used as a guide by watershed managers, planners, and decision makers for the watershed management of Lai Nullah Catchment.
