The Omaruru Delta (Omdel) aquifer near Henties Bay supplies Swakopmund, Arandis, Henties Bay, various small consumers and the Rio Tinto Rössing and Langer Heinrich mines. The current stored groundwater reserves in the Omdel are estimated at ±150 million cubic metres (Mm³), but not all of this volume can be abstracted. The recently applied pumping rate of 9 Mm³ per annum exceeded the sustainable yield of the Main Channel and certain boreholes were becoming depleted. The permit quota is therefore being reduced to 4.5 Mm³ per annum as of 2013 and the shortfall will be made up with desalinated water.

Walvis Bay, Long Beach, Namport, Rooikop airport and military base are supplied from the Kuiseb River, and there is also a pipeline from Walvis Bay to Swakopmund to supplement the supply from the Omdel.  The groundwater reserves in the Kuiseb River were replenished in 2011 to the original level that was found in the 1970s before the onset of heavy pumping. This means that the current reserves are sufficient for the next 30 years at the sustainable pumping rate of 7 million cubic metres per year. Stored reserves in the Kuiseb aquifers (including the Dorob South area) are estimated at more than 300 Mm³.

The Kuiseb and lower Swakop aquifers were replenished, but in general the area remains a water-scarce environment and even heavy rains have only a temporary effect on the supply situation.

As long as aquifer water is available domestic users will pay the current NamWater or municipal supply tariffs. Only users of desalinated water (i.e. mines) will pay desalination-related tariffs. Currently, there is no need to build a second desalination plant because NamWater has concluded a supply agreement with AREVA and obtains water from the Erongo desalination plant north of Swakopmund.

If the situation arises where a second plant is needed, it would probably be built north of Swakopmund (in the vicinity of Mile 7). Expansion plans by the mines, if implemented, would require this water by 2014-15. The date differs between the various mines and may also be subject to change. This refers to water for operational purposes and not water used for construction which would be needed earlier.

The dropping water levels in the lower Swakop River cannot be attributed to mining activities; they are due to reduce run-off and recharge caused by large upstream storage dams (Von Bach and Swakoppoort dams).  In 2011, run-off over several months completely filled up the lower Swakop aquifers and the water table is currently still only a few metres below the surface.

Abstraction of groundwater from the Khan and Swakop rivers is regulated by the Department of Water Affairs and Forestry (DWAF). A mine planning to use groundwater has to apply for a permit and demonstrate in an environmental impact assessment (EIA) that the pumping will have no negative impact on downstream users and that the local impact on the vegetation is limited. The EIA has to be accompanied by a numerical groundwater model which is submitted to the DWAF for approval. Once permitted, the impact of pumping on the water levels has to be monitored by regular observation of monitoring wells drilled into the river alluvium by the respective mine.

Please refer to the next question for an explanation why pumping of groundwater only affects the immediate vicinity of the river stretch where the pumps are situated and has a minimal effect further away from these groundwater compartments.

Studies of the Swakop river groundwater system have found that pumping – whether by farmers or by mines – only affects the underground water table over a short stretch of the river.  Rock barriers subdivide the aquifer into compartments and the main impact of pumping on water levels occurs within the river compartment (section) in which the abstraction takes place.  A compartment is typically about 20 km long and the upper and lower boundaries are defined by bedrock highs (“Grundschwellen”), which reduce the alluvium thickness and therefore also the aquifer’s saturated thickness.

The lower boundaries act like weirs and dam up the groundwater so that the water table is very shallow, sometimes reaching the surface as fountains.  Groundwater flow over these natural barriers is limited and often these boundaries are characterised by dense vegetation, resulting in increased water losses due to evapo-transpiration. Pumping near the downstream compartment boundary lowers the water level of boreholes in the upper part of that compartment; this effect can be observed in the lower Swakop farming area. Flow velocities between compartments are very slow and drawdown will not manifest itself downstream in the short term.

That depends on the locality of the abstraction wells in the Khan River in relation to the confluence with the Swakop River.  Abstraction close to the Swakop river confluence might have an impact on the water levels in the Swakop River, but abstraction from further upstream, like at the Rössing Mine, will have minor impact on the water levels in the Swakop River.

As found out by the independent consultants from Bittner Water Consult cc (BIWAC, now SLR Consulting Namibia) and the Institut für Hydrologie of Freiburg University, Germany, during the 2009-2010 groundwater specialist study for the Strategic Environmental Impact Assessment (SEIA), groundwater volumes crossing compartment boundaries are small compared to the water loss due to evaporation and evapo-transpiration. Pumping of groundwater therefore affects only the immediate vicinity of the river stretches where the pumps are situated and has a minimal effect away from these groundwater compartments.

Sand mining increases evaporation from the groundwater and reduces the water levels over the long term. Sand mining reduces aquifer capacity and will eventually reduce stored reserves in the rivers. The increased evaporation might further lead to increased salinity of the groundwater.

No, this would require the construction of a separate pipeline which would be more expensive than the supply of desalinated water.  Besides, the municipal gardens make the town more attractive for locals and tourists.

Additional, very useful information can be found at www.umwelthydrologie.de.  Get a clear picture of the aquifer dimensions and the boreholes in question, general water availability, water quality and so on.  Of particular interest is the compartment map of the Swakop and Khan River catchment areas
http://www.umwelthydrologie.de/seaweb/index.php?title=Sea:numerical_models

All findings and recommendations of the Strategic Environmental Assessment of the Erongo Region are condensed into an Executive Summary.

The Water Environment Division of DWAF is the independent institution tasked with checking the quality of NamWater‘s drinking water and that of the rural water supply schemes. In addition, various institutions have independently tested the drinking water quality at Swakopmund and Walvis Bay over the years.

The quality of Khan and Swakop river groundwater is also checked by DWAF as part of their tasks identified in the Strategic Environmental Management Plan (SEMP) of uranium mining in the Erongo region. The SEMP Office in the Ministry of Mines and Energy includes the results in its annual SEMP reports.

Tap water is sourced from groundwater in the Kuiseb and Omaruru rivers and is classified as Group B quality according to the Namibian water quality regulations.  Group B means “good quality” water that it is safe to drink, but contains slightly elevated concentrations of sodium, chloride and sulphate due to contact with the saline desert environment. The trace metal content of Swakopmund and Walvis Bay tap water was tested as part of the Strategic Environmental Assessment (SEIA) of the “uranium rush” and showed concentrations below World Health Organization (WHO) limits.

The water quality at Swakopmund and other places supplied from NamWater‘s Swakopmund reservoirs has improved through the addition of excellent quality desalinated sea water from August 2013 onwards.

The uranium concentrations of tap water from both the Omaruru and Kuiseb are below the WHO drinking water standard of 0.015 milligrams per litre.

This is one of the myths propagated by various ‘anti-nuclear’ movements. Independent studies by the Ministry of Mines & Energy in cooperation with the German Geological Survey (BGR) and the University of Freiburg, Germany, have shown that the river water in the Khan and Swakop is not contaminated by the mines and therefore not dangerous to health. Note however, that the groundwater has a natural high salinity which makes it unsuitable for human consumption and the irrigation of most vegetables (Group D quality according to the Namibian water quality standard).

Water use and effluent discharge at mines is regulated by the Department of Water Affairs & Forestry (DWAF). Mines have to apply for effluent discharge exemption permits and have to show that water quality control systems are in place to prevent effluents from entering the aquifers of the Khan and Swakop rivers. DWAF and other independent institutions check the effectiveness of the control systems. DWAF’s monitoring results on the quality of Khan and Swakop river groundwater are reported to the SEMP Office in the Ministry of Mines and Energy and included in the annual SEMP reports.

Corrosion of pumps is caused by the naturally high salinity content of desert waters, e.g. the lower Swakop groundwater contains total dissolved solids (TDS) of over 10000 milligrams per litre. Consult the pump supplier for suitable corrosion protection measures, e.g. zinc plates.

The acid that some mines use for their processes is used up and turned into neutral (non-acidic) chemical compounds. The mines have comprehensive seepage control systems in place to prevent any process chemicals from reaching the rivers and affecting the water quality.

No, the water quality is normal for desert environments.  The increase in salinity along the Khan and Swakop rivers is caused by a combination of factors:

1. Evaporation of groundwater where it is forced to the surface by underground rock barriers,
2. Evapo-transpiration through river vegetation, leaving the salts behind in the groundwater, and
3. Inflow of saline runoff or groundwater from tributaries.

If not regularly recharged by rain water runoff, this natural phenomenon will cause the continuous salting up of aquifer waters.

The uranium content varies between about 0.01 and 0.3 milligrams per litre depending on the location of the river section. Groundwater quality in the upper catchment is usually better compared to river sections in the Namib Desert. This uranium comes from the underlying geology which is naturally enriched in uranium –hence the presence of uranium mines. For millions of years, the rivers have run through the rocks which the exploration companies are now exploring for uranium, for example Bannerman at Goanikontes and Swakop Uranium further upstream.  Weathering breaks down the rocks and allows the uranium to be leached out.  Uranium forms soluble compounds that move downstream with the groundwater.

Uranium isotope ratios and other chemical “finger-printing” methods allow that distinction. No effluents potentially derived from the mines have been detected in the rivers during the recent Strategic Environmental Assessment (SEA) work done by independent laboratories.

No, the farm products are safe for consumption. Most importantly, many crops are watered with fresh water supplied by NamWater because the plants cannot tolerate brackish water from the river. Secondly, the uranium concentration of most farm boreholes is low and the uranium is mainly present in the soil. Lastly, for those plants irrigated with groundwater the uptake of uranium contained in the water or soil into the plant is low. Analyses performed on the products show that they can be safely consumed.

Additional, very useful information can be found at www.umwelthydrologie.de.  Get a clear picture of the aquifer dimensions and the boreholes in question, general water availability, water quality and so on. Of particular interest is the Compartment Map of the Swakop and Khan River catchment areas: http://www.umwelthydrologie.de/seaweb/index.php?title=Sea:numerical_models

All findings and recommendations of the Strategic Environmental Assessment of the Erongo Region are condensed into an Executive Summary.

http://www.nacoma.org.na/Downloading/Coastal-SEA_Kunene-Erongo_Final_July2008.pdf  Download PDF