ISMC2021-102, updated on 28 Apr 2021
3rd ISMC Conference ─ Advances in Modeling Soil Systems
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Quantifying the effect of post-wildfire soil water repellency on runoff

Rose Shillito1, Markus Berli2, Ian Floyd1, Li Chen2, and Teamrat Ghezzehei3
Rose Shillito et al.
  • 1USACE Research and Development Center, Coastal Hydraulics Lab, Vicksburg, United States of America (
  • 2Desert Research Institute, Division of Hydrologic Sciences, Las Vegas, NV, USA
  • 3Life & Environmental Sciences, UC Merced, Merced, CA, USA

Several factors are believed to contribute to post-wildfire flooding and debris flows. One contributing factor—the occurrence of post-wildfire soil water repellency—lacks a quantitative mechanism to incorporate the effects in physically-based runoff models. For this study, a physically-based model was developed linking the contact angle (degree of water repellency) to sorptivity. The model was verified in laboratory experiments using a silica sand proxy. The effects of water repellency on infiltration were illustrated. Further, the effect of water repellency on runoff was simulated using the AGWA-KINEROS2 watershed model with data from rainfall following the 2009 Station fire in the San Gabriel Mountains of southern California, USA. Results show water repellency has a quantifiable effect on runoff production, an effect enhanced by the dry soil moisture conditions common after wildfires.

How to cite: Shillito, R., Berli, M., Floyd, I., Chen, L., and Ghezzehei, T.: Quantifying the effect of post-wildfire soil water repellency on runoff, 3rd ISMC Conference ─ Advances in Modeling Soil Systems, online, 18–22 May 2021, ISMC2021-102,, 2021.