Effect of Changes in Environmental Flow Caused by Natural and Anthropogenic Changes on the Habitat of River Ecosystems

The damage to natural rivers, which is inevitably linked with urban development, is currently at a serious level, and as the paradigm of river management changes, interest in ecological river restoration that restores the natural characteristics of rivers is increasing. For the successful restoration of ecological rivers, habitat restoration of river aquatic ecosystems and appropriate evaluation of environmental flow should be prioritized. In this study, the Gam River, whose hydrological characteristics changed rapidly due to the construction of a multi-purpose dam, was selected as the target river. Statistical analysis, hydraulic analysis, and spatial analysis of flow regime and environmental flow were performed for hydraulic, hydrologic, and GIS analysis of river basins. The representative fish species for evaluating the environmental flow of Gam River were determined to be Zacco platypus, the dominant species in Gamcheon, and Squalidus gracilis majimae, an endangered protected species, and riparian vegetation was additionally selected to analyze the effect of changes in environmental flow. Ecosystem function model (HEC-EFM) developed by the US Army Corps of Engineers was used as the main model to analyze the impact of changes in environmental flow on the ecosystem. The environmental flow rate evaluated through EFM and eco-hydraulic model was applied to geographic river analysis system (HEC-GeoRAS) and geographic ecosystem function model (HEC-GeoEFM) to spatially depict habitats by target fish species. In addition, habitat connectivity analysis was performed along with changes in the habitat area of fish before and after dam construction.