Optimization of Water Reservoir Operation to Minimize the Economic Losses Caused by Pollution

The pollution of river water as a result of an accident can cause different types of serious damages to people, aquatic life, agricultural land, plants, and animal ecosystems. Apart from tragic events such as deaths or injuries, the accidental water pollution causes important economic losses. One effective measure is to reduce the concentration of the pollutant in the river water by adding clean water released from reservoirs placed on tributaries of the river. In this paper, we focus on finding an optimal operation of the water reservoirs (such as opening/closing time of the gates) with the goal of minimizing the total cost of the economic damages. Two components of the total cost are defined and quantified: the cost of the water used to achieve dilution and the losses caused by the existence of the pollutant in a certain concentration in the water. This problem is formalized as a non-linear multi-objective simulation-optimization model, subject to constraints. The solution is evaluated for a real use case (Jijia River, respectively, Drăcsani and Hălceni reservoirs in North–East Romania). The results are presented for two experiments. They show that by using the proposed optimization solution, the total cost of economic losses may be reduced by almost six times as compared with an empirical operation of the reservoirs and by almost $10\times $ if no dilution takes place.