Water resource vulnerability: simulation and optimisation models

Approaches to adaptation to a changing climate in water resource planning have relied on both simulation and optimisation models. Simulation models project the impacts of climate change on water system performance while optimisation models show the optimal system performance under climate change conditions. This study uses two water resource models to analyse a water resource system in Sussex (south-east England) under climatic and socio-economic uncertainty. Overall, the simulation and optimisation models show structural model uncertainty. The simulation model highlights potential vulnerability in current operational practice while the optimisation model shows that the current system could be vulnerable to climate change and demand growth even under the best case scenario. The integrated scenarios in this study combine both types, including climate scenarios from four different climate products over the time periods of 2020s, 2030s and 2050s and socio-economic scenarios represented by different demand profiles. Our results show that water demand quickly becomes a controlling factor once it increases by more than 35% from the 2007 baseline level. Both models demonstrate a gradual increasing risk of supply deficit in the 2020s and the 2030s. Water deficit risks vary widely in the 2050s and are highly dependent on the socioeconomic scenarios.