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Pacific Southwest Research Station
Tahoe Science Projects supported by SNPLMA
Development of an Online Watershed Interface to predict the effects of forest and fire management on sediment and phosphorus loads in surface runoff in the Lake Tahoe Basin
William Elliot and Randy Foltz, USDA Forest Service-Rocky Mountain Research Station
In order to reduce fire risk within forested areas in the Tahoe Basin, numerous fuel management activities to thin, harvest, burn and masticate excessive fuels are necessary. To support these activities a road network with landings is required. We propose to meet with stakeholders in the basin to determine the current fuel management activities. We will then develop watershed tools to allow mangers to evaluate the subwatershed effects of these activities in terms of fine sediment and phosphorus delivery from subwatersheds that were treated. The approach to the tool will be based on previous work supported by the SNPLMA and others. We propose to incorporate the Tahoe Basin database into the online WEPP Watershed interface to allow users to carry out watershed analyses within the Tahoe Basin. We will then enhance that online interface to include the PERL scripts developed by Brooks et al. in Round 7 to allow a more comprehensive analysis of runoff and water yield from the basin. The interface will be further enhanced to include a channel flood routing and erosion prediction currently not available with the WEPP technology. The proposed output interface will be developed to aid in interpreting model predictions, and in linking those predictions to the Tahoe Basin TMDL. To estimate the erodibility of landings, soil erodibility properties will be measured by two types of rainfall simulator and a constant head permeameter. The results added to a growing database of Tahoe-specific WEPP soil erodibility values. During the project, semiannual teleconferences will be held between the stakeholders and the research team. At the end of the project, a workshop will be held to train potential users on using the tool. A monitoring program will be initiated using flumes and turbidity meters, along with grab samples to see if sediment from forest management activities can be detected at the subwatershed scale on two disturbed and to undisturbed forested subwatersheds.
Relation to Other Research Including SNPLMA Science Projects
In Round 7 ("Assessing the sources and transport of fine sediment in response to management practices in the Tahoe Basin using the WEPP model"), Brooks et al. generated three products based on the Water Erosion Prediction Project (WEPP) Model to aid in evaluating sources of sediment in the Lake Tahoe Basin, and the effects of forest management on sediment generation. One was a database including the digital elevation model for the basin, the soil maps, the land coverage, and a weather database including all SNOTEL stations within the basin. The second product was an online interface to run individual hillslopes to estimate the runoff and sediment generation associated with wildfire and forest management. The third product was a series of calculations to use the WEPP model to predict the distribution of erosion within the basin under the current cover. In a complementary project, an online GIS interface is under development for the WEPP watershed version to allow users to run WEPP Watershed without the need to be proficient in, or even purchase a GIS. Another WEPP development is the incorporation of water quality algorithms by Forest Service researchers into WEPP runoff and sediment predictions. This study will complement the SNPLMA projects funded in Rounds 6, 7, 8, and 10 to the greatest extent possible, since many of these projects are conducted by the same PI and Co-PIs. However, the Round 12 study will develop a new online interface that has a different structure using the WEPP Watershed version, whereas the previous projects developed online interfaces based on the less complex WEPP Hillslope version. Related projects: "Improving road erosion modeling for the Lake Tahoe Basin and evaluating BMP strategies for fine sediment reduction at watershed scales," (Round 7), "The effects of climate change on Lake Tahoe, and implications for design of best management practices," "Nutrient and sediment loading predictions for prescribed fire using optimized WEPP model," and "Integrated decision support for cost-effective fuel treatments under multiple resource goals," (Round 8) and "Development and validation of the Tahoe Project Sediment Model," (Round 10).
Expected date of final products:
|Last Modified: Mar 28, 2013 02:52:08 PM|