3.3 Aquifer Hydraulics
The Atlantis Aquifer, a primary coastal system, is comprised of Cenozoic sediments of Tertiary (66 to 2.6 million years ago) and Quaternary (2.6 million years ago to present) age, overlying the Malmesbury Group bedrock which consists of greywacke and phyllitic shale as shown on Figure 9 (Van Der Merwe, 1983; Rogers, 1980).
Figure 9 – Stratigraphy of the primary coastal aquifer system in the Atlantis area (DWAF, 2010).
The aquifer covers an area of about 130 km2, stretching inland from the Atlantic Ocean to the town in the east. The thin aquifer, seldom exceeding 35 m thickness, slopes steeply in a south-westerly direction from a maximum elevation of about 160 m in the north down to sea level in the west. (Tredoux et al., 2009a).