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Evaluating Increased Erosion Potential due to Wildfires. Brian Drake CE394K – Fall 2005 Term Project Presentation. Study Area. Cedar Wildfire. Duration: 10/25/03 – 11/3/03 Size = 280,000 acres 2,232 homes destroyed 15 human deaths Suppression Cost: >$31 Mil. - PowerPoint PPT Presentation
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Evaluating Increased Erosion Potential due to Wildfires
Brian DrakeCE394K – Fall 2005
Term Project Presentation
Study Area
Cedar Wildfire
• Duration: 10/25/03 – 11/3/03• Size = 280,000 acres• 2,232 homes destroyed• 15 human deaths• Suppression Cost: >$31 Mil
Major Factors Affecting Soil Losses
• Vegetative Cover• Soil Characteristics• Topography• Intensity of Storms
Modeling Erosion
• USDA Universal Soil Loss Equation (USLE)
• A = R∙K∙LS∙C∙P– A = Soil loss per unit area– R = Rainfall-Runoff Erosivity– K = Soil Erodibility– LS = Slope Length/Steepness Factor– C = Land Cover Factor– P = Conservation Practice Factor
Rainfall-Runoff Erosivity (R)
• Reflects rainfall intensity and storm energy
Soil Erodibility (K)
• Represents susceptibility of soil to erosion
Legend0.100000002 - 0.136666669
0.136666669 - 0.173333336
0.173333336 - 0.210000003
0.210000003 - 0.246666671
0.246666671 - 0.283333338
0.283333338 - 0.320000005
0.320000005 - 0.356666673
0.356666673 - 0.393333340
0.393333340 - 0.430000007
Slope Length/Steepness (LS)
LS = (a/22.13)0.4 (s/0.0896)1.3
DEM
Land Cover Factor (C)• Ratio of soil loss based on vegetative cover
Conservation Practice Factor (P)
• Reflects impact of erosion-reduction practices
Total Sediment Potential (A)
Aave = 30.7 ton/acre/yr
Aave = 1,295 ton/acre/yr
Remaining Tasks
• Adjustments to current pre-fire calculation– Check for unit consistency– Search for more representative R-Factor– Ensure that LS value is accurate
• Modify factors to model post-fire conditions– Increase C-Factor
Resources
• DEM: http://seamless.usgs.gov/
• NHD: http://nhd.usgs.gov/data.html
• USDA Soils: http://www.ncgc.nrcs.usda.gov/products/datasets/statsgo/
• Fire Info: http://map.sdsu.edu/fireweb/
Questions?