Integrating GIS and remote sensing in environment impact assessment of Ewaso Nyiro Mega dam in Kenya

GIS is increasingly being used worldwide within Environmental Impact Assessment (EIA); However, the extent has not been well documented and therefore not well appreciated in the scientific fraternity. In this case study the National Water Conservation and Pipeline Corporation (NWCPC) on behalf of the Kenyan government engaged a consultant to identify a suitable site for a mega dam to supply water to the proposed Isiolo resort city. The consultant decision in siting the dam was not based on a comprehensive scientific analysis, as required of such a project. This could be one of the many other projects being implemented in the wrong premise courtesy of politics, and influence of leaders. The objective of this study was to review the E.I.A process carried out by the consultant to determine whether any scientific technique was employed on the identification of the ideal site for the dam. The Ewaso Nyiro basin was identified and the relevant data on dam siting collected and processed. Spatial analysis was used to inform the location of the dam based on weights realized through the Analytical Hierarchical Process (AHP). The analysis realized three suitable dam sites that were further subjected to analysis based on the local conditions to finally settle at the most suitable site for the Mega-Dam. The site slightly differs from the one fronted by the consultant in terms of capacity, inundation area, and dam crest length. The study has revealed that the most ideal site was within vicinity to the site identified by the contractor. Decisions taken regarding the length of the dam wall were noted to be misleading since no scientific approach was adopted. There is danger of implementing very noble, gigantic and capital intensive projects in the wrong premise when wrong decisions are made based on unscientific means.