Water Demand Management Scenarios in a Water-Stressed Basin in South Africa

Abstract

"Like the majority of the river basins in South Africa, water resources in the Olifants River Basin are almost fully allocated. Respecting the so-called 'reserve' (water flow reservation for basic human needs and the environment) imposed by the new Water Law adds a further dimension, if not difficulty, to water resources management in the basin, especially during the dry periods. Decision makers and local stakeholders, who will soon be called upon to work together in a decentralized manner within catchment management agencies, must therefore be able to get a rapid and simple understanding of the water balances at different levels in the basin. The Water Evaluation and Planning (WEAP) model and its application to the Steelpoort sub-basin of the Olifants are presented in this paper. This model allows the simulation and analysis of various water allocation scenarios and, above all, scenarios of users’ behavior. Water demand management is one of the options discussed in more detail here. Simulations are proposed for diverse climatic situations from dry years to normal years and results are discussed. It appears that quality of data (in terms of availability and reliability) is very crucial and must be dealt with carefully and with good judgment. Secondly credible hypotheses have to be made about water uses (losses, return flow) if the results are to be meaningfully used in support of decision-making. The ease of use of the model and its user-friendly interfaces make it particularly useful for discussions and dialogue on water resource management among stakeholders; it can also be used to promote greater awareness and understanding of key issues and concerns among the public."