Geographical Information System (GIS) as a Tool for Determining Suitable Dam Sites in the Upper West Region of Ghana

Abstract

Access to water continues to dwindle worldwide. There are global concerns over impending situations of this high-water stress, which invariably would limit domestic and industrial water usage. This development would affect the quality of livelihoods and lead to a decrease in agricultural output. Dams are one of the best options to store, use water efficiently and improve living conditions for rural and urban populations by providing water for industry, irrigation and drinking. Even though dams are designed to collect and store water for use, their best function lies in siting it appropriately. The Ghana Irrigation Development Authority (GIDA) is the government agency primarily tasked with constructing and managing dams in Ghana. The new attention of the Government in constructing dams under their flagship programme, 'one Village one Dam', necessitates research in areas where these programme objectives can be achieved. The traditional site selection process is manual, tedious and fails to accentuate certain terrain characteristics. However, using the Geographical Information system (GIS) can automate and scientifically solve this challenge with additional spatial capability. Multi-Criteria Decision Making makes use of computer tools to support the subjective assessment of performance criteria by policymakers. This study used Multi-Criteria Decision Making (MCDM) in a GIS environment in siting dams using five factors: slope, rainfall, soil type, protected zones, and Settlements. This resulted in a suitability map of sitting dam showing 4.3% suitable for dam construction, 33% of the area averagely suitable, 53.9% poorly suitable and 8.8% unsuitable for dam construction. The study recommends GIS and MCDM to effectively site dams primarily in semi-arid regions to solve the problem of dams not working efficiently because of the poor location of sites.