Date of Award

1988

Publication Type

Thesis

Degree Name

M.S.

Department

Geology

Supervisor

M.G. Sklash

Supervisor

F. Simpson

Rights

info:eu-repo/semantics/openAccess

Abstract

The Eastern Province of Kenya has both arid and semi-arid climatic conditions and drought-related problems are common. The isotopic and geochemical compositions of surface water and groundwater of the province were surveyed in an attempt to identify the sources and nature of groundwater recharge and groundwater flow directions.

The isotopic data is characterized by a large scatter in 6180, 6D, and tritium levels. The variations are due to differences in altitude and climate (temperature and rainfall) of the recharge areas.

Differences in groundwater chemistry are also evident and as in the case of isotopic composition, are the result of differences in altitude and climate. Geology is equally important in controlling the chemical composition of groundwater. Volcanic terrains have groundwater that is either magnesium or sodium-magnesium bicarbonate. Sodium chloride or sodium bicarbonate groundwaters are found in sediments. Groundwaters of variable chemical composition occur in the metamorphic rocks of the Basement System.

The isotopic and geochemical results show that the high elevation and high rainfall areas are the recharge zones for the groundwater in the low-lying arid areas. Groundwater recharge also occurs along seasonal stream valleys after heavy rains. Local groundwater recharge from precipitation on the low-lying areas is sporadic owing to aridity, and occurs only after exceptionally high rains. Evaporation of precipitation and surface-water occurs before and during the recharge processes.

Three groundwater systems are identified: the Chalbi-Kaisut Deserts; the Ewaso Nyiro-Lorian Swamp; and East Lake Turkana. Within each of these systems, different and unconnected aquifers and/or fracture zones occur.

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