GROUNDWATER A SOURCE OF WATER FOR THE DEEP SOUTH
Roger Parsons 1, John Coetzee 2 and Chris Wise 2
1Parsons and Associates Specialist Groundwater Consultants, PO Box 2606 Somerset West 7129. Tel (021) 855-2480. E-mail: [email protected] 2Jeffares and Green (Pty) Ltd
ABSTRACT
Adequate supply of water to the southern suburbs of Cape Town, including Fish Hoek, Simon’s Town and Noordhoek, is increasingly coming under threat as these suburbs expand and their demand for water increases. Upgrading and expanding existing water reticulation pipelines through Muizenberg to these areas is possible, but will be expensive and disruptive. Alternative sources of water were hence considered, including the construction of a dam at Brooklands above Simon’s Town and development of local groundwater resources. This paper describes the potential for developing groundwater resources to increase a secure supply of water to these areas.
INTRODUCTION
The area south of Clovelly – including Fish Hoek, Noordhoek, Simon’s Town, Scarborough and Kommetjie – currently obtains water from water resources above Simon’s Town (Lewis-Gay Dam, Kleinplaas Dam, and Rawson Dam) and via a pipeline running through Muizenberg and Kalk Bay. A dam site at Brooklands was identified some 30 years ago as a potential future source of water to augment existing supplies (Figure 1). In response to a land claim – parts of which would be flooded should the dam be built - the City of Cape Town investigated whether the Brooklands Dam site was still required. To be able to make an informed decision regarding the reservation of the land for construction of the Brooklands Dam at some point in the future, the City of Cape Town commissioned a study to investigate water resource and supply options for the area colloquially referred to as the Deep South. The study included an economic evaluation of various water resource and supply options, assessed the security of supply for the Deep South area and attempted to ascertain related environmental and social issues. This paper describes prevailing groundwater conditions and the feasibility of developing groundwater as a source of water for the area.
WATER DEMAND AND SUPPLY
Based on 1996 census data, the population of the Deep South is in the order of 50 000 (Figure 1). In addition to the established residential component and the naval base in Simon’s Town, a large portion of the study area comprises the Cape Peninsula National Park. The Average Annual Demand (AADD) for the Deep South area in 2001 was estimated at almost 17.0 ML/d (Jeffares & Green, 2003)(1). This includes un-metered usage (7%) and background losses (8%).
It was projected the population of the area would increase from 50 000 in 1996 to almost 100 000 by 2030. After taking account of increased service delivery and effects of water demand management, Jeffares & Green (2003)(1) predicted the AADD in 2027 would be in the order of 33 ML/d, with a peak daily demand factor of 2.2. The maximum yield of the existing water supply system was estimated to be about 30 ML/d and should be sufficient to meet project water demand until 2027. However, concerns about the age and fragility of the pipeline (risk of failure) and security of supply (reliance on a single pipeline) necessitate establishment of additional sources of water.
Proceedings of the 2004 Water Institute of Southern Africa (WISA) Biennial Conference 2 –6 May 2004 ISBN: 1-920-01728-3 Cape Town, South Africa Produced by: Document Transformation Technologies Organised by Event Dynamics Settlements
Noordhoek
Kommertjie Fish Hoek
Glencairn
Ocean View Simon’s Town City of Cape Town
Scarborough