Infrastructure
Aquifers
The Omaruru Delta (Omdel) Scheme
The scheme is located in the Omaruru Delta (Omdel) northeast of Henties Bay. In this area a precursor of the Omaruru River has incised paleochannels up to 120 m deep, which were later filled with sediments. The wellfield consisting now of 42 production boreholes was developed in the late 1970s to augment the supply from the Kuiseb River wellfields in view of the growing water demand in the region.
Overview of the Omdel Water Supply Scheme
The aquifer is found in the deeply incised Main Channel (MC), which is flanked by the Southern Channel (SEC) and Northern Elevated Channel (NEC) as well as Northern Channel System (NCS). The water in the Main Channel is fresh to slightly brackish, while both Elevated Channels and NCS contain older saline groundwater. The alluvium consists of a lower succession of coarse sand and gravel overlain by a semiconfining unit of calcareous silt to fine sand, which is topped by another sand and gravel layer. The Omdel dam and artificial recharge scheme was built to increase the sustainable yield of the aquifer to an estimated 9.8 Mm3/a (this figure was compiled in 2000 but might be revised with future investigations). The Omdel dam was completed in 1994 and has a capacity of 40 Mm3. Its purpose is to catch floodwater, which is released downstream of the dam wall after the mud has settled out. The clear water flows on surface to infiltration basins at Site 1 and 2, located respectively 6 and 11km downstream from the Omdel Dam in the Omaruru River . The water infiltrates down to the aquifer where it is protected from evaporation and available for abstraction from the existing production boreholes.
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