CHEBYSHEV MODEL FOR WATER-QUALITY MANAGEMENT

A Chebyshev criterion is used to develop robust direct regulation wate r-quality management models. The reserve capacity of the stream, in te rms of the excess capacities above the water-quality goal at the most critical water-quality checkpoints, is used as a measure of robustness of the management solutions to uncertainties in the water-quality inp ut information. The models maximize the minimum reserve capacity along the river. They are applied to the control of biochemical oxygen-dema nding waste in an example river basin based on the Willamette River in Oregon. The addition of a robustness measure in the model formulation gives additional insight into the management system. Although the mat hematical formulation of the application is simple, the results provid e important information for decision makers, such as identifying pollu ters with high waste-treatment cost per unit dissolved oxygen improvem ent at the critical stream locations. Such information is often useful for screening alternative options and making sophisticated water-qual ity policy and management decisions, based on detailed dynamic water-q uality simulation.