Hydrogeological modelling of the Atlantis aquifer for management support to the Atlantis Water Supply Scheme

Authors

  • Nebo Jovanovic CSIR, Natural Resources and Environment, PO Box 320, 7599 Stellenbosch, South Africa
  • Richard DH Bugan CSIR, Natural Resources and Environment, PO Box 320, 7599 Stellenbosch, South Africa
  • Gideon Tredoux CSIR, Natural Resources and Environment, PO Box 320, 7599 Stellenbosch, South Africa
  • Sumaya Israel CSIR, Natural Resources and Environment, PO Box 320, 7599 Stellenbosch, South Africa
  • Rodney Bishop City of Cape Town, PO Box 1694, Cape Town 8000, South Africa
  • Vernon Marinus City of Cape Town, PO Box 1694, Cape Town 8000, South Africa

DOI:

https://doi.org/10.4314/wsa.v43i1.15

Keywords:

Groundwater abstraction; managed aquifer recharge; MODFLOW; particle tracking; scenario modelling

Abstract

The Atlantis Water Supply Scheme (AWSS, Western Cape, South Africa) has been in operation for about 40 years as a means to supply and augment drinking water to the town of Atlantis via managed aquifer recharge (MAR). In this study, the numerical model MODFLOW for groundwater flow and contaminant transport was used in support of the management of the AWSS. The aims were: (i) to calibrate the MODFLOW model for the MAR site at Atlantis; (ii) to run realistic scenarios that cannot be replicated through experiments; and (iii) to make recommendations in support of efficient and sustainable management of the aquifer. MODFLOW was calibrated through comparison of observed and simulated groundwater levels (R2 between 0.663 and 0.995). Scenario simulations indicated possible drawdowns between < 5 m (low groundwater abstraction and low artificial recharge of groundwater through infiltration basins) and > 20 m (high abstraction and high artificial recharge) at localized areas of the Witzand wellfield. At Silwerstroom, large drawdown levels were not predicted to occur, so this wellfield could be exploited more without affecting the sustainability of the groundwater resource. Groundwater moves from the infiltration basins towards the Witzand wellfield at a rate of 120–150 m·a-1. The modelling results supported recommendations for balancing groundwater abstraction and artificial recharge volumes, monitoring the water balance components of the system, the potential risks of groundwater contamination and the delineation of groundwater protection zones.

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Published

2017-01-30

How to Cite

Nebo Jovanovic, Richard DH Bugan, Gideon Tredoux, Sumaya Israel, Rodney Bishop, & Vernon Marinus. (2017). Hydrogeological modelling of the Atlantis aquifer for management support to the Atlantis Water Supply Scheme. Water SA, 43(1 January). https://doi.org/10.4314/wsa.v43i1.15

Issue

Section

Research paper