Changes in High- and Low-Flow Regimes: a Diagnostic Analysis of Tropical Cyclones in the Western North Pacific

This study aims to determine the characteristics of hydrological behaviors in the basins of the representative multipurpose dams in the Korean Peninsula that depend on typhoon conditions for sustainable water management and restoration of the water ecosystem. Based on the annual maximum flow and seven-day low-flow results, trend analyses were conducted on hydrological changes, such as magnitude, timing, duration, and frequency of the extreme flows. Among the eight selected multipurpose dams in South Korea, the Chungju and Soyang dams have been subject to dramatic reduction of inflow during the spring and early summer. The Sumjin Dam was indicated the most sensitive to the severity and magnitude of typhoons and it showed a statistically significant increase in the frequency and duration of peak inflows resulting from such typhoons. As regards low flow, the Chungju and Andong dams showed a distinct reduction in this flow in the winter, but the changes resulting from typhoons were relatively subtle. This diagnostic study is expected to provide foundational data to examine the causalities related to the streamflow patterns of Korean basins. In addition, the study could aid in establishing basin-customized mid- and long-term measures for supplying of water resources in the environmental system and for managing the effects of natural disasters by analyzing various hydrological changes related to extreme events.