The development of a Water Quality Systems Assessment Model (WQSAM) and its application to the Buffalo River Catchment, Eastern Cape, South Africa

Water law in South Africa subscribes to the Integrated Water ResourcesManagement (IWRM) paradigm by seeking to provide equitable access of water toall users including the ecosystem. The management of water resources to be inline with IWRM policies is seen to be a major challenge in South Africa due toincreasing demands, problematic water quality impacts and concerns over futureclimate change and development impacts. Because of limited resources withinwater resources management, simple models may be more useful than complexmodels (Young et al. 1996). An existing yield model, the Water ResourcesModelling Platform (WReMP) is well established within water resourcemanagement in South Africa, and this study outlines the development of a WaterQuality Systems Assessment Model (WQSAM) that is specifically designed tointerface with the water quantity inputs and outputs of WReMP. WQSAM has beendesigned to give useful predictions of water quality using the available observeddata, and uses an approach that is oriented to risk management. WQSAM includesmodules for simulating water quality variable inputs from diffuse source and pointsources as well as the fate of water quality variables in-stream and withinreservoirs. Future developments include the application of WQSAM to the Amatolasystem in the Eastern Cape, South Africa. WQSAM will include Thresholds ofPotential Concern (TPCs), as well as a Decision Support System (DSS) specific tothe Amatola system.