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Pacific Southwest Research Station
Tahoe Science Projects supported by SNPLMA
Laboratory experiments on fine particle capture by submerged vegetation in stream environment zones (SEZs): the effects of vegetation density, biofilm development and particle composition
Geoff Schladow, Tahoe Environmental Research Center, University of California, Davis
This proposal focuses on the measurement of fine particle capture efficiencies in a laboratory flume using analogs of the vegetation present in a stream environment zone (SEZ). The laboratory flume offers the ability to vary flow rate, substrate density (stems per square meter), stem width, particle concentration, and presence/absence of biofilms (biological surface coatings) in a repeatable fashion and to measure the changing particle size distribution and particle concentration over time. The size-specific removal efficiencies that can be calculated in this way can then be used as the basis for assigning removal efficiencies in any SEZ in the Tahoe Basin based on site-specific flow rate, vegetation type and density, and initial particle concentration. The values can also be used as part of a comprehensive stream/SEZ model and provide more detailed estimates of the effectiveness of SEZs in achieving restoration goals. The output from the proposed study can be used as the basis of site selection for future capital projects involving the use of SEZs for fine sediment removal, as the basis for assigning credits to project implementers for particle and nutrient removal, and as the basis for the design of sophisticated pump-back systems where flow through "treatment SEZs" could be controlled to better maximize fine particle removal.
Relation to Other Research Including SNPLMA Science Projects
The research is directly linked to ongoing research supporting environmental improvement projects in the Tahoe Basin. The PI is currently leading a Round 8 SNPLMA study to model and measure floodplain processes in the Trout Creek watershed ("Potential of engineered flood plains and wetlands as fine-particle BMPs: case study of Trout Creek and the Upper Truckee River"). The present project seeks to obtain similar data under fully controllable conditions, so that future and ongoing field measurements by others can be compared with the lab data and so a broader range of flow and environmental conditions will be possible. The PI is also conducting a SNPLMA Round 9-funded field study on biofilm development and particle capture in a stormwater detention basin, "Measuring the ability of floodplains to treat urban runoff in the Lake Tahoe basin." These studies are closely tied; in particular, the Cattleman's study will help inform the question of how quickly a biofilm gets established on natural vegetation. Data from this experiment is scheduled to be collected during the winter/spring of 2010/2011 and so will be able to inform the design of the proposed lab experiments. Agencies need methodologies to design and site BMPs and local implementers want to receive appropriate credit for installing projects to reduce the particle load to the lake. Establishing confidence in the particle removal efficiencies will help restoration projects to more effectively use monitoring resources.
Expected date of final products:
|Last Modified: Mar 7, 2013 06:28:06 PM|