Identification of Potential Sites for Rainwater Harvesting Structures in Akwa Ibom State, Nigeria: RS and GIS Approach

Water is the most essential resource on earth for life's existence. Changing hydrological phenomena and increase of water demand generally, create serious water scarcity problems. Precipitation and underground water are major sources to mitigate this problem. Construction of water harvesting structures across watersheds is gaining drive recently to improve efficiency and effectiveness in water availability, supply, use, and water demand for various purposes. In this study, geographical information system (GIS) and remote sensing (RS) techniques integrated with multi-criteria analysis were used to achieve study objectives – identify possible locations for water harvesting structures using GIS and structure type. Considering the complexity of identification of the water harvesting structures sites, Analytical Hierarchy Process (AHP) was used to determine the weight of importance of five criteria used for the suitability analysis: rainfall, slope, drainage density, land cover and soil texture. These factors were ranked based on their importance to water harvesting structure and the weight generated from the AHP, the criteria were combined using the weighted overlay techniques (WOT). Dam and pond locations were identified from the suitability map generated. 1.06% and 1.88% of the study area fall within areas of high suitability for pond and dam constructions respectively. The highly suitable area falls within the area of very high rainfall intensity and a gentle slope