Ecohydraulic model development and application: Evaluating the habitats and population of rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), and flannelmouth sucker (Catostomus latipinnis) in Colorado River

Ecohydraulics often requires the use of advanced numerical models and ecological theories, which are used for river and aquatic organism management. In this study, a 2D ecohydraulic model system was proposed and used to evaluate the habitat suitability index, weighted useable areas, overall suitability index, fish population number, and fish population density of Colorado River. The 2D ecohydraulic model system comprised hydrodynamic, hydromorphology, habitat, and population models. Three fish species were selected as target fish, which included rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), and flannelmouth sucker (Catostomus latipinnis). Five computational domains of the Colorado River were selected for the ecohydraulic model. The surveyed fish data from 2000 to 2009 were used to calibrate the model system. Results indicated that the predicted fish number showed a good agreement with the surveyed fish. It is indicated that the rainbow trout and brown trout fish number showed decreasing trends from 2000 to 2009, while flannelmouth sucker showed increasing trend from 2000 to 2009. The proposed approach demonstrates that the ecohydraulic model system can be used to accurately simulate the river habitat quality and population status. The ecohydraulic model can be an efficient tool to improve understanding of the different scenarios and to assistant for multiple fish habitat and population prediction in river system. It can also provide decision-makers with valuable information to optimize their management. (C) 2020 The Author. Published by Elsevier B.V.