The Influence Of Groundwater Management Strategies On Groundwater Levels Of Namibian Savannah Aquifers

ABSTRACT 

Namibia has been known as water-scarce, attributing mostly to its geographic location and primarily because of the limited surface water as well as the high potential evaporation rates beyond 2000 mm/year. Groundwater therefore quickly becomes crucial, most of which is located in aquifers in the savannah biome which covers a large part of the country. This is also where most industrialization, as well as most farming, is practised. It is however unknown how these savannah aquifers are managed on a local scale and how the management strategies influence the long term groundwater levels of the aquifers. To understand these strategies, three research sites along a rainfall gradient, namely Tsumeb area, Waterberg and Kuzikus area were studied. Through means of a self-developed questionnaire tailored for the government officials and farmers, five (5) interviews were conducted with government officials at DWAF. Across all three research sites a total of seventeen (17) farmers were interviewed. For the scientific groundwater management strategy, the sustainable yield was calculated using the catchment area and the recharge of the area. The short-term volume available was calculated for each research site using the formula Volbal = G*Sy (ϕave - ϕmin). The quantitative data from these four strategies were modeled using the Processing MODFLOW modelling software. The results show that the government strategy employed makes use of the Water Act no 54 of 1956. In comparison with the regulatory guidelines such as carrying capacity, many farmers abstract greater volumes per Small and Large livestock unit per hectare. However they have a similar influence on the groundwater levels over time when compared to the government policy guided strategy. The influence on groundwater levels by the farmer and policy guided strategies are well within the scientific sustainable yield strategy.