Hydrodynamic modelling of physical habitat conditions for fish in the Ekso river near Flatekval
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In this study, a 2D hydrodynamic model HEC-RAS is used to simulate the flood inundation, water depths and flow velocities of the river reach in the Eksingedal watercourse near Flatekval in western Norway. The objectives are to simulate the water depths and flow velocities with different scenarios and to assess the effect of flood regulation on habitat quality of the brown trout. The data is pre-processed and post-processed in ArcGIS. The model is set up and calibrated from historical flow data as well as the flood inundation area of the drone image. In addition, the sensitivity analysis of various factors such as roughness values, mesh resolution and time steps are conducted. Based on the results from the 2D HEC-RAS model, the information about the suitable area for different life stages of the brown trout and the distribution of the different habitats are obtained. This area covers the requirements of water depth and flow velocity for fish of different life stages decreases after regulation. Based on literature review, other factors (for example shore vegetation, water temperature, water chemistry, fish food etc) that may have affected the fish population are also discussed.