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Pacific Southwest Research Station
Tahoe Science Projects supported by SNPLMA
Quantifying the potential for a low-cost, distributed stormwater detention system using LiDAR and remotely-sensed data
Geoff Schladow, University of California-Davis
The input of fine sediment particles (and associated nutrients) to Lake Tahoe has been identified as a major cause of clarity decline over the last 40 years (Roberts and Reuter, 2007). Efforts to reduce fine sediment inputs, particularly from the highly contributing urbanized areas adjacent to the lake, are the main focus of the recently signed Total Maximum Daily Load (TMDL) for Lake Tahoe. This project seeks to utilize newly acquired LiDAR data and other remotely-sensed data to identify and quantify the potential to develop stormwater detention and infiltration areas based on small-scale patterns of land topography. Utilizing the high vertical accuracy and resolution inherent in the existing LiDAR data set, it is feasible for the first time to identify the hydrologic connectivity and the topographic features of the urban areas and the Wildland Urban Interface (WUI) areas in the entire Tahoe Basin. Based on this information it is now possible to identify the volume of Micro Stormwater Infiltration Systems (MSIS) achievable by small modifications to existing culverts, construction of small retaining walls, and in relatively simple ways utilizing the features of the existing topography. Remotely-sensed data and current GIS layers will show whether these MSIS areas intrude on private property, existing infrastructure, sensitive lands etc. The project will (1) quantify the volume of stormwater detention available through this means; (2) test the methodology on an existing urban area in collaboration with a local agency; (3) rank the individual MSIS by volume (largest to smallest) within each basin watershed; (4) working with local jurisdictions assign a water quality weighting to each of the volume-ranked MSIS that indicate the highest influx of fine sediment particles; (5) develop a methodology whereby the accumulated sediment in an MSIS can be sampled, analyzed for particle size distribution and thereby provide firm data for the assignment of TMDL credits and validation of existing crediting tools (such as the Pollutant Load Reduction Model [PLRM]); and (6) make available a design tool utilizing the Tahoe Environmental Research Center's existing 3-D visualization laboratory where agencies can easily view and design these MSIS in an immersive three-dimensional environment using the LiDAR data and other spatial data.
Relation to Other Research Including SNPLMA Science Projects
This research is based on the use of both the LiDAR and the WorldView2 datasets acquired through the Round 10 SNPLMA capital program, as well as using other GIS layers that have been developed by the agencies over many years (for example, vegetation maps and Natural Resources Conservation Services soil maps). In addition, the project will utilize products currently being derived from the LiDAR data set under Round 11 SNPLMA research funding, specifically the impervious surface map being developed under the project, "Mapping hard and soft impervious cover in the Lake Tahoe Basin using LiDAR and multispectral images: a pilot study of the Lake Tahoe Land Cover and Disturbance Monitoring Plan." With the products and tools developed with this Round 12 research, agencies will have an ability to consider a broad range of stormwater management options that can be located at the most critical locations taking into account current and future land uses. This work is targeted at what has been determined to be the most pressing environmental improvement issue facing local agencies – finding economical and effective ways to reduce movement of fine sediment and nutrients to Lake Tahoe. With the signing of the TMDL August 2011, basin regulatory agencies and the local jurisdictions have now entered the phase of undertaking projects that will reduce fine sediment and nutrient inputs to the lake. The results of this investigation will be useful to the Tahoe Regional Planning Agency as it develops projects and implements the Environmental Improvement Plan to meet TMDL load reduction targets. It will also help the California Tahoe Conservancy, Nevada Division of State Lands and the USDA Forest Service as owners of some multi-purpose yet small parcels to best management these properties. Local governments have received load reduction requirements as part of the newly approved Lake Tahoe TMDL. The results from this study will allow them to better identify cost-effective pollutant reduction opportunities within their jurisdictions.
Expected date of final products:
|Last Modified: Mar 7, 2013 06:28:14 PM|