Multi-Criteria-GIS Based Site Selection for Irrigational Reservoir – A Case Study

Abstract

Water scarcity is a fundamental problem in the Upper East Region of Ghana especially in these recent years. The region has only two main reservoirs which collect both stream and run-off water from highlands for usage. Most of the rivers are seasonal and carry water only after rainfall, making the total land area dry most of the year. Women and children walk a number of hours to reach shallow hand-dug wells or ponds, which they share with livestock. The people have been facing these water shortages over the years and construction of good dams is a possible solution to meet the future demand of water supply. In order to address the above water challenges, there is a need for a system that can consider all spatial factors to selecting dam site and GIS techniques as well as Multi-criteria Decision Analysis (MCDA) are more appropriate. The site selection was based on the factor and constraints criteria. Weights were assigned to the factors using Pairwise comparisons and the layers were overlaid and weighted. A total of 4 optimal dam sites were selected after incorporating the various factor and constraint criteria. The existing land use should be visited in the selected sites before constructing the dams and population should be reviewed to see whether changes in population affect the siting of irrigation dams in an area.