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sur le développement des zones arides et semi-arides

Titre : Groundwater recharge estimation of the Malewa catchment, Naivasha Kenya

Auteur : Graham, Angella

Etablissement de soutenance : International Institute for Aerospace Survey, Netherlands

Grade : Master of Science (MSc) 1998

Résumé
Groundwater recharge is that amount of surface water which reaches the permanent water table either by direct contact in the riparian zone or by downward percolation through the overlying zone of aeration. It is this quantity which may in the long term be available for abstraction and which is therefore of prime importance in the assessment of any groundwater resource. Groundwater recharge quantification to the Lake Naivasha is very important as there is a growing demand placed on the present available water resources. The lake currently supports intensive irrigation-based agriculture, geothermal power, fishery and tourist industries. Because of its shallow nature it is subject to considerable variation in water level.This study uses the analysis of baseflow in an attempt to quantify groundwater recharge in the Malewa catchment. A soil water budget ’WTRBLN’ was also used to validate the results obtained by baseflow analysis. EC routing was used to evaluate groundwater inflow into the catchment. These results indicate that baseflow vary between 60 and 290 mm/year. An average annual baseflow contribution of 60 mm/year was calculated as inflow to the Lake Naivasha.. This represents approximately 8% of the effective rainfall that occurs over the catchment. Total inflow, that is, baseflow and surface inflow to the lake was estimated to be 137 mm/year.

Sujets : Lake Naivasha ; Groundwater ; Watershed ; Malewa river ; Irrigation ; Hydrology ;

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