Abstract
<jats:p>This research assesses the Soil Conservation Service curve number (SCS-CN) loss method’s suitability for postfire hydrologic processes. The SCS-CN method, favored for its simplicity, was not designed for post-wildfire application. We evaluated two existing methods that adjust the SCS-CN model for wildfire effects and proposed a revised method. This new method adjusts the initial abstraction ratio (λ) and CN based on antecedent soil moisture conditions. Three wildfire-impacted Southern California watersheds were modeled using the SCS-CN method. Prefire data were used to estimate the average CN for each subbasin, which were then used to evaluate the SCS-CN methods for postfire application. This study found that unadjusted SCS-CN application underestimated excess-precipitation volume and peak discharges. The Higginson method had mixed success, while the Livingston method overestimated peak discharges and excess-precipitation volume. The revised method performed best when compared against observed data using various performance metrics. The study concludes that adjusting λ and CN based on antecedent root zone soil moisture conditions consistently improved model performance. The overestimation by the Livingston method underscores the need for caution when applying regional methods.</jats:p>