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

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

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?