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BERG RIVER MONITORING PROGRAMME

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Announcements

Background

The Western Cape System Analysis Study, conducted between 1989 and 1995, assessed the future growth of water demands in the greater Cape Metropolitan Area and surrounds and studied options for meeting or moderating these demands. One of the options considered was the development of Skuifraam Dam and the Skuifraam Supplement Scheme for the upper reaches of the Berg River.

As part of the pre-feasibility investigation of Skuifraam Dam, the instream flow requirements (IFR) for the Berg River at various sites along its length were identified on the basis of motivations for flows to drive a range of biological and physical processes in the river. These flows were identified during a series of workshops, held in 1992 and 1993, and subsequently refined in 1996. At the end of 2001, another workshop was held to re-visit certain of the flood requirements of the refined IFR. In each case, motivations for particular flow regimes for ecosystem maintenance were made on the basis of best available knowledge, but it was acknowledged that much work is necessary to deepen scientific understanding of the relationship between desired or essential ecological processes and a particular flow magnitude or its frequency, and thus increase the sophistication of how the effects of different levels of flow modification are quantified. In this respect, a programme to monitor the effects of the artificial flow regime imposed by the construction of any dam would need to be established in order to:
· confirm compliance with the IFR,
· verify the nature and accuracy of the changes to the ecosystem that were predicted as a result of the dam,
· determine the effectiveness of the environmental flow releases (the IFR) in terms of their predicted effects on ecosystem processes, and
· facilitate the implementation of adaptive management where undesirable and/or unpredicted changes in ecosystem characteristics are detected. Such adaptive management would seek to minimise the impacts of these changes.

Prior to construction of a dam, however, the baseline ecological, physical /chemical, hydrological, hydraulic and social conditions of the river system, including its associated groundwater, estuarine and floodplain components, would need to be established, to allow clear identification of future changes as a result of implementation of the IFR, as well as to guide the post-construction monitoring programme itself.