Geophysical and hydrogeological investigations for groundwater in the lake Kenyatta settlement scheme, Lamu district, coast province, Kenya.

Abstract

This thesis presents results of geophysical and hydrogeological investigations for groundwater' in the Lake Kenyatta settlement scheme: Lamu District, Coast Province: Kenya. During the Pleistocene; the area was a beach and had sand dunes which have since been eroded and filled up with sand giving the present undulating relief. Inversia'n of ground resistivity sounding data yields resistivities and thicknesses that are consistent with geology. The area consists mostly of highly fissured coral limestone 5-30 m thick underlying a low resistivity substratum comprising sands: clays, sandy clays and clayey sands. The deeper coral limestone layers show consistent low resistivities, perhaps due to hard water in the solution caverns. The geoelectric sections reveal a pinch and swell structure of the coral limestone underlain by marine sediments. The freshwater/saltwater interface consistently displays an undulating wavy structure at a de:.,',h of 20 to 40 m below the ground surface and extends over the entire area.