USING REMOTE SENSING AND ELECTRICAL RESISTIVITY TO EXPLORE FOR GROUNDWATER IN RURAL KENYA

This research investigated the potential of using remote sensing and surface electrical resistivity as means of finding clean drinking water for the Mt Kasigau community in southeast Kenya. This community experiences water shortages that result in many households going without running water for many hours everyday. In addition, much of the surface-water sources suffer from bacterial contamination. Groundwater exploration and development would help alleviate the water problems facing this community. Remote sensing and electrical resistivity provide non-invasive and economically viable tools for groundwater exploration. This study investigated the use of these tools in this rural area.

Landsat Thermatic Mapper and Enhanced Thermatic Mapper images were analyzed in EDRDAS IMAGINE and ArcGIS. The images were utilized to identify areas with potential for groundwater by identifying features that would indicate presence of shallow groundwater. These features included linear features, abandoned river channels, certain soil types, surface moisture and vegetation distribution. The analysis yielded several maps showing the spatial distribution of these features. An overly of these maps was used to identify and produce a final map showing areas with relatively high potential for shallow groundwater development.

Electrical resitsivity sounding using a MiniRes resitsivity meter (L and R Instruments Inc) was conducted at five sites within the study area to begin verifying the remote sensing results. Three of the sites were chosen from areas shown on our final overlay map as having a high potential for groundwater; the fourth site was chosen randomly. Based on the resistivity sounding results, the three sites selected as likely having shallow groundwater had water tables that were between 15 and 21 m below ground surface and are likely in coarse, unconsolidated deposits. At the fourth randomly-selected site the water table depth was > 33 m. Deeper investigations are required to delineate the extent of the water bearing material, and areas need further testing based on drilling logs and pumping tests.