Measurement and prediction of post-fire erosion at the hillslope scale, Colorado Front Range

Abstract

Post-fire soil erosion is of considerable concern because of the potential decline in site productivity and adverse effects on downstream resources. For the Colorado Front Range there is a paucity of post-fire erosion data and a corresponding lack of predictive models. This study measured hillslope-scale sediment production rates and site characteristics for three wild and three prescribed fires over two summers and one winter using 48 sediment fences. Over 90% of the sediment was generated by summer convective storms. Sediment production rates from recent, high-severity wildfires were 0.2–1.0 kg m–2 year–1. Mean sediment production rates from areas recently burned at moderate and low severity were only 0.02 and 0.005 kg m–2 year–1, respectively. For a given severity, sediment production rates from prescribed fires were generally lower than from wildfires, but there was considerable variability between plots and within fire severity classes. Fire severity, percent bare soil, rainfall erosivity, soil water repellency and soil texture explained 77% of the variability in sediment production rates, while a two-parameter model using percentage bare soil and rainfall erosivity explained 62% of the variability. Model validation confirmed the usefulness of these empirical models. The improved understanding of post-fire erosion rates can help guide forest management and post-fire rehabilitation efforts.