Integrating Fluvial Geomorphology and Two-Dimensional Hydraulic and Sediment Transport Modeling to Support Sustainable Design of Large River and Floodplain Improvements: The Trinity River Corridor Project, Dallas, Texas, USA

The Trinity River Corridor Project in Dallas, Texas will realign and naturalize eight miles of the Trinity River channel and create a wide variety of recreational and habitat features on the floodplain within the boundaries of the Dallas floodway. Major flood control projects in the 1920s and 1950s relocated, straightened, and channelized the river, and regular mowing on the floodplain has maintained homogenous conditions with limited habitat value. Primary river naturalization elements of the project include restoration of channel meanders, creation of more natural channel geometry, integration of natural geologic controls into the channel profile, and creation of an oxbow lake. Floodplain improvements include creation of wetlands, lakes, recreational features such as trails and playing fields, and establishment of more natural vegetation assemblages. This suite of channel and floodplain improvements will create more complex hydraulics and sediment transport characteristics that will strongly influence the operation and maintenance of the Project area, and therefore the overall sustainability of the Project. Therefore, the design of channel and floodplain features has been guided by detailed analysis of historical geomorphology of the Project site and the region, and two-dimensional hydraulic and sediment transport modeling of the proposed channel and floodplain design. We present results from the integrated fluvial geomorphology and two-dimensional hydraulic and sediment transport modeling based design process introduced in Tompkins et al (2008) and describe how these results, which included velocity and shear stress distribution and sediment deposition patterns, were used to develop and refine channel alignment, geometry, and bank treatment designs as well as configuration and design of floodplain features.