A sensitivity-based analysis for managing storage capacity of a small agricultural reservoir under drying climate

Reservoirs have played a vital role in sustaining agricultural production and human livelihood with changing environments and demands. While expanding the storage capacity of a reservoir is deemed a robust structural adaptation that improves water allocation, few studies have discussed the sensitivity of this approach to climatic stresses. In this study, we investigated the effectiveness of building and upsizing reservoirs on addressing water scarcity under climate change in a simple reservoir system in South Korea. We employed a sensitivity-based framework that combines a stochastic system analysis and climate projections, and assessed the response of mean water scarcity to climatic stresses. Results showed that building or upsizing a reservoir made system performance more responsive to climatic stresses. Although additional reservoir capacity can help reducing water scarcity, the effectiveness of such an approach is expected to diminish rapidly when climate becomes drier. If existing climate changes towards drier conditions, performance achieved through additional storage capacity decreases more rapidly, resulting in lager performance loss than before making structural measures. This study suggests that the direction of climate change and operational upgrades should be considered to reduce potential shortcomings associated with the structural adaptation strategies for a simple reservoir system.