Author(s): Rohan Benjankar
Linked Author(s): Rohan Benjankar
Keywords: Integrated modeling; Hydraulic model; Water temperature; Fish habitat; Habitat shift;
Abstract: Water management causes natural flow regime alteration, which is one of the main human impacts on freshwater ecosystem. Generally, flow regime alteration negatively affects aquatic habitat, channel connectivity to floodplain, side-channel and backwater habitats, which are important for both terrestrial and aquatic species. We developed an integrated modeling framework that includes watershed hydrologic, hydraulic, stream water temperature and fish habitat selection criteria to assess the impacts of hydrologic alteration on spatial and temporal distribution of fish habitat. Hydrologic model was coupled with energy-based snowmelt model to simulate watershed flows, which was used as boundary conditions for one- and two-dimensional hydrodynamic models to simulate channel hydraulics and water temperature. Hydrodynamic models were calibrated with field survey water surface elevations, flow velocities and water temperatures for different channel flow conditions. Hydrodynamic model simulated water depths, flow velocities and water temperatures were used as inputs to a fish habitat model to simulate spatial and temporal habitat distribution as a function of natural (without dam management) and dam released flows. Our results indicated water temperature is a critical parameter that alters habitat. Furthermore, high quality habitat shifted from the main channel to lateral-channel during high flow periods. This process shows the importance of lateral-channel habitat. Numerical modeling and understanding of interaction between physical and biological processes provided an opportunity to develop integrated modeling tools to analyze human impacts at a watershed scale. This tool is helpful for analyzing the effect of water management, restoration activities and climate changes on aquatic habitat distribution.