Author:
Brogan Daniel J.,Nelson Peter A.,MacDonald Lee H.
Abstract
Abstract. Post-wildfire landscapes are highly susceptible to rapid geomorphic changes, and the resulting downstream effects, at both the hillslope and watershed scales due to increases in hillslope runoff and erosion. Numerous studies have documented these changes at the hillslope scale, but relatively few studies have documented larger-scale post-fire geomorphic changes over time. In this study we used five airborne laser scanning (ALS) datasets collected over 4 years to quantify erosion and deposition throughout the channel network in two ∼15 km2 watersheds, Skin Gulch and Hill Gulch, in northern Colorado after a wildfire followed by a large, long-duration flood 15 months later. The objectives were to (1) quantify the volumes, spatial patterns, and temporal changes over time of erosion and deposition over a nearly 4-year period, and (2) evaluate the extent to which these spatially and temporally explicit changes are correlated to precipitation metrics, burn severity, and morphologic variables. The volumetric changes were calculated from a differencing of DEMs for 50 m long segments of the channel network and associated valley bottoms. The results showed net sediment accumulation after the wildfire in the valley bottoms of both watersheds, with greater accumulations in the wider and flatter valley bottoms in the first 2 years after burning. In contrast, the mesoscale flood caused large amounts of erosion, with higher erosion in those areas with more post-fire deposition. Only minor changes occurred over the 2 years following the mesoscale flood. Volume changes for the different time periods were weakly but significantly correlated to, in order of decreasing correlation, contributing area, channel width, percent burned at high and/or moderate severity, channel slope, confinement ratio, maximum 30 min precipitation, and total precipitation. These results suggest that morphometric characteristics, when combined with burn severity and a specified storm, can indicate the relative likelihood and locations for post-fire erosion and deposition. This information can help assess downstream risks and prioritize areas for post-fire hillslope rehabilitation treatments.
Funder
Division of Emerging Frontiers in Research and Innovation
Division of Earth Sciences
National Institute of Food and Agriculture
Subject
Earth-Surface Processes,Geophysics
Reference116 articles.
1. Abbott, J. T.: Geology of Precambrian rocks and isotope geochemistry of shear
zones in the Big Narrows area, northern Front Range, Colorado, US Geological
Survey, Open-File Report OF-70-1, 1970. a
2. Abbott, J. T.: Geologic map of the Big Narrows quadrangle, Larimer County,
Colorado, US Geological Survey, Geologic Quadrangle Map GQ-1323, 1976. a
3. Abrahams, E. R., Kaste, J. M., Ouimet, W., and Dethier, D. P.: Asymmetric
hillslope erosion following wildfire in Fourmile Canyon, Colorado, Earth
Surf. Process. Landf., 43, 2009–2021, 2018. a
4. Anderson, H. W.: Fire effects on water supply, floods, and sedimentation, in:
Proceedings Tall Timbers Fire Ecology Conference, 249–260, 1976. a
5. Baker, V. and Costa, J.: Flood power, in: Catastrophic Flooding, edited by:
Baker, V. and Costa, J., 1–21, Allen and Unwin, 1987. a
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