Response of Fish Community to Building Block Methodology Mimicking Natural Flow Regime Patterns in Nakdong River in South Korea

Water regulation and flood control of rivers are changing due to streamflow depletion following industrialization urbanization, significantly impacting aquatic ecosystems. Therefore, restoration the ecological environment is necessary maintain a healthy river ecosystem. For ecosystem restoration, amount discharge from dams must be controlled appropriate environmental flow calculated according fish species. The change in through dam hydropeaking directly impacts fish. This study aimed construct building block methodology (BBM) using inflows Gudam Bridge basin upstream Nakdong River, build River2D model this area, calculate natural regime weighted usable area (WUA). analysis scenarios for whole period (2006–2020) by showed that WUA decreased some periods, but improved overall scenario reflecting BBM. Zacco platypus, dominant species Bridge, ~11% periods (in September) habitat improvement effect measured up 79%. Changing pattern considering seemed more effective improving living downstream.