Why is Groundwater Important?
Namibia is the driest country in sub-Saharan Africa and depends largely on groundwater. With an average rainfall of about 350 mm per annum, the highest rainfall occurs in the Caprivi in the northeast (about 600 mm per annum) and decreases in a westerly and southwesterly direction to as little as 50 mm and less per annum at the coast. The only perennial rivers are found on our national borders with South Africa, Angola, Zambia and the short border with Botswana in the Caprivi. In the interior of the country surface water is available only in the summer months when rivers are in flood after exceptional rainfalls. Otherwise, surface water is restricted to a few large storage dams retaining and damming up these seasonal floods and their runoff. Thus, where people don’t live near perennial rivers or make use of the storage dams, they are dependent on groundwater to provide for their water needs. From a geographic and water consumer viewpoint, it is therefore clear that a very large proportion of the Namibian population is dependent on groundwater for their (economic) livelihood, and this in itself justifies that we share knowledge about our groundwater resources. Despite considerable investment in drilling, borehole design and construction as well as pumping and maintenance, groundwater is usually the most economic way of supplying water. The advantage of using groundwater sources is that even isolated communities and those economic activities located far from good surface water sources such as mining, agriculture and tourism can be supplied from groundwater over nearly 80 % of the country.
What is the Status of Groundwater in Namibia?
Over the past century, more than 100 000 boreholes have been drilled. Half of these are still in operation and produce groundwater for industrial, municipal and rural water supply. They provide drinking water to man, livestock and game, irrigation water for crop production and supply distant mines.
However, groundwater resources, being closely associated with underground rock types that vary with the geological situation, are unevenly distributed across the country. At the southern, northern and northeastern borders where surface water is available throughout the year from perennial rivers, there is an excess rather than a shortage of water, although this is shared with neighboring countries. The rest of the country either relies on dams constructed in ephemeral rivers that have low safe yields in comparison to their total volume, because of drought and high evaporation losses, or on groundwater. Some areas are favorable, sitting on high-yielding, very productive aquifers that contain more water than farmers and communities presently need. Numerous small springs, fountains and seeps throughout the country sustain wildlife, man and livestock. In other areas, groundwater conditions are unfavorable due to limited water availability, little and unreliable recharge, low borehole yields, great depths, poor groundwater quality and high risks of contamination.
In addition, many individuals (mainly commercial farmers) do gather data of inestimable value for groundwater management privately, but such data only become available if others know about them and specifically ask for them.
The most important factors to be addressed and corrected are:
Raising awareness: Groundwater does not receive the recognition and prominence it deserves, and all role players, from the highest political authority to the individual owner and consumer of groundwater, must realize the value of groundwater as well as the fact that it is extremely vulnerable to human impact.
Capacity: It includes sufficient, practically enforceable and appropriate policy and legislation, including relevant, well-organized and equipped authorities to implement, monitor and regulate the sustainable use of groundwater at all levels. In order to do this, it requires the need for well qualified hydrogeologists.
Knowledge base: The knowledge of individual groundwater schemes (using small parts of larger aquifers) is generally good, and also the knowledge of selected study areas (such as the artesian basins of Stampriet and Oshivelo). However, a knowledge-base in respect of the wider groundwater surroundings has to be extended on a national level and must also be honed with respect to the accuracy and reliability of all groundwater data. There is the need to consider the formulation and establishment of policy with respect to the availability of data (data sharing), also with neighboring countries, and a commitment must be in place to carry through such policy.
More detailed information on groundwater and groundwater in Namibia:
- Hydrogeological map of Namibia - Western part [2,556 KB]
- Hydrogeological map of Namibia - Eastern part [2,086 KB]
- Department of Water Affairs Namibia: Groundwater in Namibia - an explanation to the hydrological map - 2011 [608 KB]
- Van Vuuren: A Namibian perspective (English) - 2011 [1,442 KB]
- Van Vuuren: 'n Namibiese perspektief (Afrikaans) - 2011 [1,231 KB]
- Cap-Net: Groundwater management in IWRM - training manual - 2010 [7,187 KB]
- GW MATE: Sustainable groundwater management groundwater - 2010 [2,659 KB]
- BGR: Groundwater and Climate Change: Challenges and Possibilities - 2008 [1,348 KB]