Scenario analysis for energy saving and management optimization in complex water supply systems

The pumping schedules optimization of complex water supply systems considering different hydrological scenarios occurrences is a significant issue when defining the activation of emergency and costly water transfers. As well known, this problem is characterized by a huge uncertainty level and it requires specific stochastic models in order to achieve optimized management rules. Particularly, treating the effectiveness of early warning and emergency transfers alleviating droughts, the operating costs required by pump stations activation stress the water systems’ Authorities to define a robust approach identifying these optimized rules. In this paper, this optimization procedure has been developed using the scenario analysis approach. The model allows identification of the optimal management rules by balancing the risk of water shortages under different hydrological scenarios and the energy costs due to the pumping stations operation. Scenario analysis optimization provides the water resource management Authority with information defining optimal activation thresholds for pumping stations in order to assure a water demand level fulfillment for users (irrigational, civil, industrial) and an energy saving policy. This optimization model has been implemented using the software GAMS, specifically designed for modelling mixed integer optimization problems. A model application has been developed to a real water supply system located in South-Sardinia (Italy) area. The obtained results define a cost-risk trade-off considering water shortage probability minimizing energy and operative costs.