Optimising water allocation and land management to mitigate the effects of land use and climate change on reservoir performance

Future changes in land use, climate and downstream water demand can impact reservoir water supply performance. However, a comprehensive assessment that considers these factors poses challenges as it requires complex scenario simulations. To improve our understanding of potential combined effects and to facilitate analyses of reservoir performance, the Soil and Water Assessment Tool has been coupled with genetic optimization and applied to a case study, the Nuicoc multipurpose reservoir in Vietnam. Optimization analyses under a range of scenarios show that despite greater future rainfall, climate change combined with increases in urban area and agriculture resulted in 1-10% and 4-28% lower reliability and resilience, respectively, compared with the baseline. Reservoir sedimentation led to a vulnerability index increase of 0.1-10.5 and 150-400 Mm(3)/year greater water spillage. Reservoir performance can be improved by adjusting water allocation policies and best management practices in the watershed.