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

Hydrological Processes
By: , and 

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Abstract

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 ( urn:x-wiley:hyp:media:hyp11458:hyp11458-math-0001) 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 urn:x-wiley:hyp:media:hyp11458:hyp11458-math-0002 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 urn:x-wiley:hyp:media:hyp11458:hyp11458-math-0003 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.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Incorporating spatially heterogeneous infiltration capacity into hydrologic models with applications for simulating post‐wildfire debris flow initiation
Series title Hydrological Processes
DOI 10.1002/hyp.11458
Volume 32
Issue 9
Year Published 2018
Language English
Publisher Wiley
Contributing office(s) Geologic Hazards Science Center
Description 13 p.
First page 1175
Last page 1187
Country United States
State California
Other Geospatial Santa Ana Mountains