Integrated Approach for Optimizing the Design of Aquifer Storage and Recovery Stormwater Harvesting Schemes Accounting for Externalities and Climate Change

Harvested stormwater is now being considered as an alternative water source in a number of cities because of concerns over water scarcity and population growth. However, the availability of this source varies as a result seasonality and climate change. This paper introduces an approach for optimizing the design of a stormwater harvesting scheme including aquifer storage and recovery that explicitly takes into account future climate change and its impact on the optimal design of the scheme. The proposed approach also accounts for the externalities associated with the use of harvested stormwater. The approach is applied to a specific case study in South Australia, considering four possible climate scenarios for planning horizons of 2030 and 2050 and the additional benefits of reducing withdrawals from the river source and the salinity of the water supplied. Results show that climate change will reduce the yield and the net present value (NPV) of the optimal stormwater scheme. They also indicate that there is a trade-off between the average NPV and the variation of the NPV across the different climate scenarios: smaller basins and a smaller wetland are selected to maximize the average NPV, while, to minimize the range of the NPV values, larger harvesting basins and smaller wetlands are implemented. For the case study, the externalities considered have a small impact on the overall cost-effectiveness of the solutions.