Ephemeral river systems and their ecosystem provisions to the local populations
A review of the Huab and Ugab Rivers, Namibia.
Keywords:Ephemeral Rivers arid aquifers, Alluvial sand aquifer, Water supply, Ephemeral communities
Ephemeral rivers have been the source of domestic and livestock water for millennia in Africa. In Namibia, crystalline and alluvial groundwater aquifers in ephemeral rivers are the only source supporting livelihoods. The aim of this paper is to review the existing literature on these two ephemeral river systems, with a specific objective to investigate the knowledge gaps in these arid areas of the Huab and Ugab ephemeral systems. These rivers lie in proximity of the marginal
populations and support a great number of livelihoods, and economic activities. The aridity dynamics are fundamental factors that influence ecological aspects of the ephemeral rivers that support at least one- fifth of the Namibian population. The rivers only flow for a period of two weeks per year, and in wet years, some may flow for three weeks. The rivers have a highly evolved ecological system that is sustained by the high hydrologic variation which is the main ecological driver. These ephemeral rivers transport sediment, fine particulate matter, and organic matter in form of tree and woody matter that is generally deposited downstream as a result of hydrologic decay. The study found that knowledge on hydrological and ecological patterns of the Huab and Ugab ephemeral rivers are limited, in spite of their catchments being the main supportive systems to the economically marginal populations. There is also a lack of understanding on how the ecosystem provision influences the livelihoods of the local populations. The study recommends further research on ecological reserves, linking to ecosystem provision of these natural systems (natural future bank of resources).