Delineation of Rainwater harvesting Potential Zones using analytical hierarchy process (AHP) and GIS in District Swat

Abstract

Water is critical to all life forms in watershed. There is intense need of water for human and animal consumption as well as for agriculture, forest, and rangeland management. Water scarcity have a tremendous stress to water-shed productivity. Water sources in form of precipitation plays a vital role in water distribution in semi-arid and arid regions. Delineation of rain-water harvesting potential zone is a basic issue for the areas where water resources are deficient or with no proper irrigation system for agriculture. The current Study deal with the identification of rainwater harvesting potentiality zones in district Swat of Khyber Pakhtunkhwa. Therefore, it is necessary to select some suitable sites based on required and essential parameter such as land-use/land-cover, geology, rainfall, soil, slope, drainage density, lineaments, geology, elevation are selected as major and minor influencing factor responsible for delineation of these zones. The weight and score of each influencing factor is derived using analytical hierarchy process (AHP). Each influencing factor were assigned a weightage based on saatys’ scale table depending upon their effectiveness to the rainwater harvesting potentiality. By using the command of weighted overlay in ArcGIS spatial analyst too, all the thematic layers were integrated resulting delineation of rainwater harvesting potential zones. The potential zones were classified into four groups, i.e., (1) Least Suitable Site, (2) Not Suitable Site, (3) Suitable, and (4) More Suitable Site. This study revealed that zones with a More Suitable Site covered an area of 314 km² (6 % of the total area), Suitable Site 1720 km² (32 %), Not Suitable Site 1815 km² (34 %), and Least Suitable Site 1505 km² (28 %).   The study concluded that the geospatial-assisted Analytical Hierarchy Process was very useful and efficient technique for the delineation of rainwater harvesting potential zones and effectively can be applied to enhance the conceptual understanding of rainwater harvesting of District Swat, Khyber Pakhtunkhwa Pakistan