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Table 2. Subbasin characteristics, burn severity, modeling parameters, and computed peak discharge for pre- and post- burn subbasin conditions, Willow Creek. [mi', square miles; %, percent; Qn, n-year discharge; ft'/s, cubic feet per secondl Runoff curve 0,,,, (ft'/s) number Basin name and number Drainage Area of Area of Pre-burn Post- Pre- Post- area (mi') low burn medium to burn burn burn (%) high burn (%) Willow 1 9.993 0.0 0.0 70.87 70.87 329. 329. Willow 2 1.182 3.4 2.5 66.17 69.85 43.5 82.3 Willow 3 1.260 15.1 0.4 66.22 71.47 37.7 94.8 Willow 4 1.892 40.1 45.0 64.37 91.18 39.9 1,470. Willow 5 1.604 14.0 0.0 65.48 70.40 35.0 87.9 Willow 6 1.790 19.6 12.2 66.53 79.20 41.0 344. Willow 6a 0.89 20.4 116. Willow 6b 0.60 13.7 181. Willow 6c 0.30 6.9 46.7 Willow Creek at mouth 17.72 359. 1,550. Post-Fire Hydrology Runoff after wildfire, produced by a storm of a given size, is generally many times larger than pre-burn watershed discharge. Post-fire (FEMA phase 2) hydrology represents conditions that are expected to exist before substantial recovery of soil properties and regrowth of vegetation in the burned areas. Assumptions for the short-term post-fire, Phase 2 hydrology of Willow Creek were as follows: 1. Rainfall runoff was simulated for the 100-year, l-hour storm for post-fire conditions in burned drainage basins tributary to Willow Creek. . A rainfall depth of 1.60 inches (100-year, I-hour storm) was applied uniformly over each basin, with no area distribution of the storm (Miller and others, 1973). 2. Peak discharges for selected reaches of Willow Creek were computed (with hydrologic routing of the runoff hydrograph). Runoff curve numbers were selected to correspond to the burned condition within each subbasin. Existing post-fire hydrologic response studies were used to select RCNs for post-burn conditions (Elliott and others, 2005). . Unburned area =: pre-burn value · Low burn severity =: 85 . Moderate and high burn severity =: 98