Multi-objective optimization of the management of a waterworks using an integrated well field model

This study uses multi-objective optimization of an integrated well field model to improve the management of a waterworks. The well field model, called WELLNES (WELL field Numerical Engine Shell) is a dynamic coupling of a groundwater model, a pipe network model, and a well model. WELLNES is capable of predicting the water level and the energy consumption of the individual production wells. The model has been applied to Søndersø waterworks in Denmark, where it predicts the energy consumption within 1.8% of the observed. The objectives of the optimization problem are to minimize the specific energy of the waterworks and to avoid inflow of contaminated water from a nearby contaminated site. The decision variables are the pump status (on/off), and the constraint is that the waterworks has to provide a certain amount of drinking water. The advantage of multi-objective optimization is that the Pareto curve provides the decision-makers with compromise solutions between the two competing objectives. In the test case the Pareto optimal solutions are compared with an exhaustive benchmark solution. It is shown that the energy consumption can be reduced by 4% by changing the pumping configuration without violating the protection against contamination.