Integration of water quantity and quality in strategic river basin planning

The integration of surface water quantity and quality objectives within the framework of a decision-support tool is presented in an application to the 12,400-km(2) Piracicaba River Basin in the state of Sao Paulo, Brazil. Emp hasis is given to simulation-based assessment of strategic planning alterna tives through the combined use of water allocation (MODSIM) and water quali ty routing (QUAL2E-UNCAS) models. Uncertainty from temporal and spatial var iability and inadequate data associated with model parameters is addressed. Performance measures for water allocation include total reliability, total vulnerability, and total resiliency. Water quality performance measures ar e stream standard compliance reliability, water quality index, spatial unif ormity of water quality, and temporal uniformity of water quality. These me asures are used to evaluate and compare alternatives in light of multiple p lanning objectives. Six management alternatives, combining various reservoi r release policies with differing levels of wastewater treatment, are refin ed through systematic simulation to a final plan recommended for detailed c onsideration. The recommended plan results in predicted performance that de pendably meets transbasin diversion to the city of Sao Paulo while maintain ing high intrabasin water allocation performance.