Groundwater assessment and sustainable management of the coastal alluvial aquifers in Namib Desert, Namibia: Omdel Aquifer as case study

Abstract

The study addressed the groundwater assessment and sustainable management of the coastal alluvial aquifers in Namib Desert, the Omaruru River Delta Aquifer (Omdel Aquifer) was used as a case study. Sustainable utilization of groundwater in parts of hyper-arid Sub-Saharan Africa, like the Namib Desert, is always a challenge due to lack of resources and data. Understanding of hydrogeological characteristics of the Omaruru Delta Aquifer System is a pre-requisite for the management of groundwater supply in the Central Namib area (Namib Desert). For the Omdel Aquifer in the Omaruru catchment, Namibia, issues to investigate include the lack of information on the geology and hydrogeological setting, the hydraulic properties and geometry of the aquifer at the inflow and outflow sections, groundwater recharge conditions upstream of the aquifer, and the impact of artificial recharge. Omdel Aquifer occurs in a desert environment with less than 20 mm of rainfall per annum, it’s regarded to receive no direct groundwater recharge from rainfall, only from occasional (inconsistent) flooding of the Omaruru River, due to periodic thunderstorms in the upstream catchment. Since the Omdel Aquifer does not receive direct recharge from rainfall, an artificial recharge scheme was implemented to augment the water supply. One of the objectives of the study is to integrate artificial recharge with hydrogeological understanding of the Omdel Aquifer to establish a conceptual framework for assessment of groundwater recharge and discharge, water chemistry and balanced water supply.