Fountain Creek Watershed Flood and Sediment Transport Study
Study Area: Fountain Creek Watershed, Colorado
Period of Project: October 2010 – December 2013
Project Number: RE00EDN
Project Chief: Michael Kohn, P.E.
Cooperator: Fountain Creek Watershed, Flood Control and Greenway District
The U.S. Geological Survey, in cooperation with the Fountain Creek Watershed Flood Control and Greenway District, assessed remediation scenarios to attenuate peak streamflows and reduce sediment loads in the Fountain Creek watershed. To evaluate these strategies, the U.S. Army Corps of Engineers Hydrologic Engineering Center (HEC) hydrologic and hydraulic models were used. The U.S. Army Corps of Engineers modeling system HEC-HMS (Hydrologic Modeling System) version 3.5 was used to simulate runoff in the Fountain Creek watershed associated with storms of varying magnitude and duration. The U.S. Army Corps of Engineers modeling system HEC-RAS (River Analysis System) versions 4.1 and 4.2 were used to simulate streamflow and sediment transport, respectively, for the Fountain Creek watershed generated by particular storm events and by a design-storm event.
HEC-RAS model simulations used to evaluate the 14 remediation scenarios were based on unsteady-state streamflows associated with a 24-hour, 1-percent annual exceedance probability (100-year) National Oceanic and Atmospheric Administration Type II precipitation event. Scenario 0 represents the baseline or current conditions in the watershed and was used to compare the remaining 13 scenarios. Scenarios 1–8 and 12 rely on side-detention facilities to reduce peak flows and sediment transport. Scenario 9 has a diversion channel, and scenario 10 has a reservoir. Scenarios 11 and 13 incorporate channel armoring and channel widening, respectively. Scenarios 8 and 10, the scenario with the most side-detention facilities and the scenario with the reservoir, respectively, were the most effective at reducing sediment transport and peak flow at the Fountain Creek at Pueblo, Colorado, streamgage 07106500. Scenarios 8 and 10 altered the peak flow by –58.9 and –56.4 percent, respectively. In turn, scenarios 8 and 10 altered the sediment transport by –17.7 and –62.1 percent, respectively.
- Update hydrologic models (HEC-HMS) previously developed by URS, Inc. (2006a) and calibrate them using precipitation and streamgage data from real storm events for the Fountain Creek watershed.
- Update hydraulic models (HEC-RAS) previously developed by URS, Inc. (2006b, 2003) and calibrate them using streamgage data from real storm events for the Fountain Creek watershed.
- Build and calibrate a sediment transport model (HEC-RAS) using sediment and streamgage data from real storm events for the Fountain Creek watershed.
- Simulate 14 scenarios using the models (HEC-HMS and HEC-RAS) to evaluate the effectiveness of different remediation elements throughout the Fountain Creek Watershed by reducing peak flows and sediment transport.