3.2 The Source Water
There are no major rivers flowing through the Atlantis area. The only surface water features in the area include the Buffelsriver at Silwerstroom, and during winter, the Donkergat and Sout rivers which flow to the south of the Atlantis area (DWAF, 2010). All of these are non-perennial rivers that dry up during summer. Perennial springs feeding the Buffelsriver at Silwerstroom have been used for water supply since 1976. Due to the large infiltration capacity of the soil in Atlantis, there is minimal overland flow in the area.
In the case of Atlantis, stormwater and treated domestic wastewater became the source water. The town (17 km2) generates large volumes of stormwater due to the presence of extensive impermeable surfaces. The recharge basins in Atlantis receive on average about 750 m3/d of stormwater and domestic wastewater which equates to approximately 2.7 Mm3/year contribution to the Atlantis water supply. This is equivalent to 30 percent of the area’s water supply.
A total of 12 stormwater retention and detention basins capture stormwater from the residential and industrial areas. Industrial stormwater is separated from residential stormwater due to the potential of higher salinity water from industrial activities (Tredoux et al., 1999). The combined stormwater from the residential area and the treated wastewater is directed to the artificial recharge basins as shown on Figure 8 (DWAF, 2010). Industrial effluent and excess stormwater are directed to coastal recharge basins, and seep into the ocean via the subsurface, also preventing saline intrusion (Bugan et al., 2016).