Numerical Model Based Analysis of River Training and Habitat Structures on River Processes: Straubs Bend of the Missouri River

Habitat structures such as the Interception Rearing Complexes (IRC) are intended to aid endangered species such as the larval pallid sturgeon by increasing the movement of larval sturgeon out of the main river channel and into the channel margin through the construction or modification of river training structures. The studied IRC are designed to create fish pathways that access the lower velocities and generally shallower depths in the channel margin where juvenile sturgeon have a chance to mature in areas with critical food resources. A Two-Dimensional (2D) Adaptive Hydraulics/Sediment Library (AdH/SEDLIB) depth-averaged, shallow-water, finite element model has been created to study the potential effects that the construction of an IRC may have on other factors, such as long-term bed morphology, navigation, velocity distribution, water surface elevations, and potential flood risk. The model simulates a stretch of river under consideration for the construction of IRC structures. First, the model was set up with pre-existing riverbed and structure geometry. The model was validated for a period between 2017-2020. After calibration, the model was run with the implementation of the proposed IRC structure geometry and compared to system behavior without IRC construction. The validated model was used to evaluate the effects of the proposed IRC on other river processes, by performing simulations both with and without the implementation of the IRC and analyzing inter-model comparisons. The presentation will focus on the details of the modeling system including numerics, application and analysis of results.