Incorporating spatially heterogeneous infiltration capacity into hydrologic models with applications for simulating post-wildfire debris flow initiation

Luke A. McGuire, Francis K. Rengers, Jason W. Kean, Dennis M. Staley, Benjamin B. Mirus

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Soils in post-wildfire environments are often characterized by a low infiltration capacity with a high degree of spatial heterogeneity relative to unburned areas. Debris flows are frequently initiated by run-off in recently burned steeplands, making it critical to develop and test methods for incorporating spatial variability in infiltration capacity into hydrologic models. We use Monte Carlo simulations of run-off generation over a soil with a spatially heterogenous saturated hydraulic conductivity (Ks) to derive an expression for an aerially averaged saturated hydraulic conductivity (Ke*) that depends on the rainfall rate, the statistical properties of Ks, and the spatial correlation length scale associated with Ks. The proposed method for determining Ke* is tested by simulating run-off on synthetic topography over a wide range of spatial scales. Results provide a simplified expression for an effective saturated hydraulic conductivity that can be used to relate a distribution of small-scale Ks measurements to infiltration and run-off generation over larger spatial scales. Finally, we use a hydrologic model based on Ke* to simulate run-off and debris flow initiation at a recently burned catchment in the Santa Ana Mountains, CA, USA, and compare results to those obtained using an infiltration model based on the Soil Conservation Service Curve Number.

Original languageEnglish (US)
Pages (from-to)1173-1187
Number of pages15
JournalHydrological Processes
Issue number9
StatePublished - Apr 30 2018


  • debris flows
  • hydraulic conductivity
  • infiltration capacity
  • run-off
  • wildfire

ASJC Scopus subject areas

  • Water Science and Technology

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