Estimating Groundwater Recharge Rates and Identifying Groundwater Recharge Zones in Kakia and Esamburbur Sub-Catchment Narok, Kenya

Abstract

Groundwater recharge has become a significant practice for sustainable groundwater development and efficient water resource management. Many countries in Africa including Kenya are currently experiencing water scarcity. For instance, Kakia and Esamburmbur sub-catchment, Narok County in southwest Kenya suffers water shortage during the dry season and surface water sources dry up. Identifying groundwater recharge zones and estimating groundwater recharge rates in Kakia and Esamburmbur sub-catchment will help water-resource authorities and policymakers to properly plan and develop groundwater resources in the sub-catchment. A geophysical survey was executed using the PQWTs-500 equipment to understand the sub-surface condition of the study area in order to determine the suitable recharge zones. Five profile lines were generated of 20.9 KM in total with 104 points at 200 m intervals. Soil and Water Assessment Tool plus (SWAT+) model was used to estimate groundwater recharge rates in the sub-catchment. The SWAT+ model was calibrated and validated with sixteen years of monthly satellite soil moisture data. The geophysical survey results showed that the south-central and southeast zones of the sub-catchment are potentially good groundwater recharge zones and therefore suitable for managed aquifer recharge structures to augment the groundwater resources. And the SWAT+ simulation showed that the long-term average groundwater recharge rate rages from 0 to 175 mm per year. It was also observed that the highest groundwater recharge occurs in April, May and, June.