Pacific Southwest Research Station

Potential of Floodplains to Retain Fine Sediments

This research will quantify the potential for the Upper Truckee River and other flood plains to retain fine sediments by linking, calibrating, and validating an urban hydrology model (SWMM) and a flood-plain sediment model (SIFT2D-WQ).

Full Title: Potential of engineered flood plains and wetlands as fine-particle BMPs: case study of Trout Creek and the Upper Truckee River

Proposal [pdf]

Lead Researchers: Geoffrey Schladow and John Reuter, University of California, Davis; Fabian Bombardelli, University of California, Davis

Goals

1. Develop, calibrate, and validate a two-dimensional hydrodynamic/water quality model to quantify the removal efficiency for fine sediment and nutrients in the Trout Creek and Upper Truckee River watersheds.
2. Determine the features of flood plains that have the largest effect on fine sediment and nutrient removal (e.g., residence time, vegetation density and distribution, turbulence sources).
3. Use the model to design methodologies to maximize the efficiency of flood plains as best management practices (BMPs).
4. Evaluate the basinwide potential and costs of flood plains as BMPs.

Modeling Approach

1. An urban stormflow model (SWMM) will be set up for the urban areas that drain to the Trout Creek flood-plain site
2. The SWMM model inputs, combined with measured stream inflows and data collected from turbidity sensors and bottle samples at the upstream and downstream model boundaries (see figure above), and the topographic survey and vegetation distribution will provide the necessary boundary conditions for the 2-D flood-plain model, SIFT2D-WQ.

Timeframe: August 2008 through September 2010 (2 years)

Products

1. Calibrated and validated urban stormwater model and flood-plain hydrodynamic and water quality model, including manual and sample input datasets
2. Report quantifying and describing sediment/nutrient removal efficiencies and mechanisms on the Trout Creek flood plain
3. Report describing the performance of hypothetical flood-plain projects on the Upper Truckee River, methodologies for improving their performance, their benefits in fine sediment removal, and the costs of such projects relative to other BMPs for sediment removal
4. Exhibit to be displayed at the UC Davis Tahoe Environmental Research Center describing wetland function as determined by the study results