Using GIS and Multi Criteria Decision Making to Determine Suitable Dam Sites in The Upper West Region of Ghana

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Date
2019-10
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KNUST
Abstract
The availability of water for use is alarmingly becoming an issue of concern globally and if measures are not implemented to curb this, then the world over faces an impending water scarcity crisis. Studies conducted by the United Nations Environment Program (UNEP) indicate that by 2050, over two billion people will live under high water stress situations. This invariably would limit development and affect quality of lives. Water scarcity and water stress situations will also invariably lead to a decrease in Agricultural output. Dams provide an option for harvesting and storing water for various uses. Irrigation could also be a solution to the decline of agricultural output in the country. However, even though dams are designed to collect and store water for use, for them to function at optimum levels, they have to be sited appropriately. In Ghana, the Ghana Irrigation Development Authority (GIDA) is the government agency primarily tasked with the construction and management of dams. However selecting suitable sites for these dams is done manually and quiet subjectively. This traditional site selection process is tedious fails to accentuate certain terrain characteristics that are not readily visible and may only be highlighted in a GIS environment This study employs the use of GIS and Multi Criteria Decision Making (MCDM) in siting dams using five factors namely Slope, Rainfall, Soil type, protected zones and Settlements. The results shows a suitability map for dam sites. From the map, 4.3% of the study area is suitable for dam construction, 33% of the area averagely suitable, 53.9% poorly suitable and 8.8% unsuitable for dam construction. The study goes further to propose four specific dam sites, determined the profiles and estimates volumetric capacities of these sites and it was found that the sites had capacities of 219,000m3, 1,312,500m3, 557,666m3 and 375,000m3 respectively for dam sites 1, 2, 3 and 4. In conclusion, it is asserted that GIS is a powerful tool that can be effectively used to help in determining suitable sites for dam construction and provides an improvement on the current traditional site selection process employed by decision makers.
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A thesis submitted to the Department of Geomatic Engineering, Kwame Nkrumah University of Science and Technology, Kumasi in Partial fulfilment of the requirements for the award degree of MASTER OF PHILOSPHY IN GEOGRAPHIC INFORMATION SYSTEMS
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