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Observed and simulated hydrologic response for a first‐order catchment during extreme rainfall 3 years after wildfire disturbance
Author(s) -
Ebel Brian A.,
Rengers Francis K.,
Tucker Gregory E.
Publication year - 2016
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1002/2016wr019110
Subject(s) - surface runoff , infiltration (hvac) , environmental science , hydrology (agriculture) , drainage basin , runoff curve number , subsurface flow , geology , groundwater , meteorology , ecology , geography , geotechnical engineering , cartography , biology
Hydrologic response to extreme rainfall in disturbed landscapes is poorly understood because of the paucity of measurements. A unique opportunity presented itself when extreme rainfall in September 2013 fell on a headwater catchment (i.e., <1 ha) in Colorado, USA that had previously been burned by a wildfire in 2010. We compared measurements of soil‐hydraulic properties, soil saturation from subsurface sensors, and estimated peak runoff during the extreme rainfall with numerical simulations of runoff generation and subsurface hydrologic response during this event. The simulations were used to explore differences in runoff generation between the wildfire‐affected headwater catchment, a simulated unburned case, and for uniform versus spatially variable parameterizations of soil‐hydraulic properties that affect infiltration and runoff generation in burned landscapes. Despite 3 years of elapsed time since the 2010 wildfire, observations and simulations pointed to substantial surface runoff generation in the wildfire‐affected headwater catchment by the infiltration‐excess mechanism while no surface runoff was generated in the unburned case. The surface runoff generation was the result of incomplete recovery of soil‐hydraulic properties in the burned area, suggesting recovery takes longer than 3 years. Moreover, spatially variable soil‐hydraulic property parameterizations produced longer duration but lower peak‐flow infiltration‐excess runoff, compared to uniform parameterization, which may have important hillslope sediment export and geomorphologic implications during long duration, extreme rainfall. The majority of the simulated surface runoff in the spatially variable cases came from connected near‐channel contributing areas, which was a substantially smaller contributing area than the uniform simulations.