Pacific Southwest Research Station

Measuring the Ability of Floodplains to Treat Urban Runoff

Full title: Measuring the ability of floodplains to treat urban runoff in the Lake Tahoe basin

Lead Researchers: Geoffrey Schladow, Tahoe Environmental Research Center, University of California at Davis; Stefan Wuertz, Department of Engineering, University of California at Davis

Abstract

The project seeks to measure the mechanisms and the efficiency of fine particle removal from urban stormwater using floodplains. The project is based in the Cold Creek/Trout Creek floodplain, and utilizes the Cattlemans detention basin and the floodplain immediately downstream of it. Experiments separating the role of biofilm processes and gravitational settling will be conducted within the detention basin, and on the floodplain downstream of the basin in response to both natural overflows of the basin and pumped flows of urban stormwater. The goals of the project are to (1) quantify the effects of gravitational settling and biofilm processes in the removal of very fine (<20 micron) particles from urban stormwater and to (2) determine the elemental composition of both the stormwater itself and the particulate material to assess the potential for negative impacts to the resident floodplain biota and their food webs. This information will be used to help calibrate and validate a two-dimensional floodplain model that will enable floodplains to be designed to optimally treat urban stormwater.