| dc.description.abstract | Groundwater prospecting in Garissa County, Kenya, has been haphazard and expensive due to lack of information on the appropriate areas for hydro-geological exploration and subsequent drilling of boreholes. With no pre-analysis information on the suitability of sites for groundwater potential, drilled dry boreholes have resulted in wastage of enormous valuable resources. In this study, we explored the use of Geographic Information Systems and Remote Sensing as a pre-analysis tool to classify areas according to their potential for ground water for Garissa County.
The objective of the study was to develop a groundwater potential zones map for the County for use in the selection of prospective sites suitable for drilling of boreholes. First, the main factors that contribute to the occurrence of groundwater in an area were identified to be land cover, soil, and lithology. The textural data for the factors was downloaded from International Livestock Research Institute (ILRI) website. Secondly, Weighted Index Overlay Analysis (WIOA) modelling was applied to generate the Groundwater potential zones Map. The three thematic factor data for the county was converted from vector to raster and reclassified to a common measurement scale. The factors were then weighted using Analytic Hierarchical Process (AHP), the weight (index) of each factor being its relative percentage contribution to the occurrence of ground water compared to the others. ArcGIS 10.1 Spatial analyst tool was used to add the weighted factors to produce the groundwater potential zones map. Finally, the predicted groundwater potentials zones were verified using yields of existing boreholes.
Verification of results indicated that the model correctly predicted areas with poor potential while it gave average results for areas with good potential for groundwater. Exploration in areas with good potential will require additional use of other available information such as yields and depths of existing boreholes to evaluate the final result. | en_US |
