Targeting of rainwater harvesting structures using geospatial tools and analytical hierarchy process (AHP) in the semi-arid region of Rajasthan (India).

Burgeoning population growth and subsequent demand for freshwater, besides competition among irrigation, domestic, and industrial sectors, coupled with a changing climate, have necessitated prudent and effective management of water resources. Rainwater harvesting (RWH) is considered one of the most effective strategies for water management. However, the location and design of RWH structures are essential for proper implementation, operation, and maintenance. An attempt has been made in this study to locate the most suitable site for RWH structure and design using one of the robust multi-criteria decision analysis techniques, viz. analytic hierarchy process, using geospatial tools in the Gambhir watershed, Rajasthan, India. High-resolution Sentinel-2A data and a digital elevation model of the Advanced Land Observation Satellite were used in this study. Five biophysical parameters, viz. land use and land cover, slope, soil texture, surface runoff, and drainage density, were considered to identify suitable locations for RWH structures. It was observed that runoff is the prime factor in determining the location of RWH structures compared to other parameters. It was revealed that 75.54 km (13% of the total area) was very highly suited for the construction of RWH structures, while 114.56 km (19%) was highly suitable. A total of 43.77 km (7%) of land was determined to be unsuitable for the construction of any type of RWH structure. Farm ponds, check dams, and percolation ponds were suggested for the study area. Furthermore, Boolean logic was used to target a particular type of RWH structure. The study indicated that a total of 25 farm ponds, 14 check dams, and 16 percolation ponds can be constructed at identified locations in the watershed. Water resource development maps of the watershed generated using an analytical approach would be useful for policymakers and hydrologists for targeting and implementing RWH structures in the study watershed.