TITLE:
Groundwater Modelling of Motloutse Alluvial Aquifer, Eastern Botswana
AUTHORS:
Edwin O. Keaitse, Nata T. Tafesse, Berhanu F. Alemaw, Kebabonye Laletsang, Read B. M. Mapeo
KEYWORDS:
Alluvial Aquifer, Groundwater, Hydraulic Conductivity, Motloutse River, Eastern Botswana
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.16 No.10,
October
31,
2024
ABSTRACT: The potential groundwater reserve in alluvial aquifers and sandy river beds has not been well studied, and yet their benefit in meeting rural water supply demands cannot be underestimated. A three-dimensional steady-state finite difference numerical groundwater flow model was used to assess the groundwater resource potential on a one-kilometre river stretch scale along the Motloutse River catchment in eastern Botswana. The model area is a single-layer unconfined aquifer system. A uniform grid was laid over this phreatic aquifer, and an overall size of 50 columns x 54 rows was developed. The model yielded calibrated K values of 145 m/day and 11 m/day for the riverbed and riverbank sediments, respectively, and calibrated recharge and evaporation of 172 mm/yr and 120 mm/yr, respectively. A sustainable groundwater yield of 120 m3/day with the potential to irrigate an area of 2.4 hectares was determined. The result also shows that the Motloutse alluvial aquifer yields a safe yield of 29,400 m3 for a kilometre of river stretch.