Establishing a Phased Drought-Response System Based on Available Supply Days

The increasing variability in rainfall patterns due to climate change has led to frequent and extreme droughts in the Yeongsan and Seomjin River basins in the southwestern part of South Korea, exposing the limitations of existing water-management systems that rely on independent facility operations. To address this challenge, this study moved beyond simple indicators based on reservoir storage rates and introduced “Available Supply Days” as a key metric to assess the actual supply capacity of each water source quantitatively. Based on this metric, a phased drought-response system was established. The study defined the dry season following the flood season as the “Drought-Response Period” and proposed a standard for the conjunctive operation of water resources with three evaluation checkpoints (October, January, and April). A simulation applying this proposed standard to the Dongbok Dam during the severe drought of 2022-2023 demonstrated significant results: while reservoir depletion was predicted in March in the absence of an initial response, the implementation of phased measures—including demand management and emergency conjunctive operations with hydroelectric dams (Bosong River Dam) and river water (Yeongsan River)—successfully secured stable water supply until the rainy season. The significance of this study is its presentation of practical guidelines for enhancing extreme drought resilience through the integrated conjunctive operation of available water resources within a river basin, without the need for large-scale physical infrastructure expansion.