A programming model for river quality management under transverse mixing

Abstract

The objective of river quality management is to achieve a given water quality standard at certain control stations by cutting down the pollutant load in the basin at the lowest cost. Conventional programming models, however, cannot guarantee the satisfaction of the quality standard at each drinking water intake when transverse mixing occurs in the river, because they focus on the average concentration of the cross sections, while the raw water is usually drawn from the sides of the river. In this paper, a programming model is proposed to deal with waste load allocation problems. The effect of transverse dispersion on the quality at drinking water intakes is taken into account by introducing an index which represents the degree of mixing in a river. This has made it possible to link the sewage system planning with the improvement of drinking water quality. The results of model application show that the priority of sewage treatment in a river basin is quite different from those advanced by the conventional models. It is suggested that a change of the traditional strategy of waste load allocation is necessary for better quality of drinking water supply.