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Browsing Research Data by Subject "floods"
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Item Open Access Dataset associated with "Spatial and temporal patterns of sediment storage and erosion following a wildfire and extreme flood"(Colorado State University. Libraries, 2019) Nelson, Peter A.; Brogan, Daniel J.Post-wildfire landscapes are highly susceptible to rapid geomorphic changes at both the hillslope and watershed scales due to the increases in infiltration-excess overland flow, hillslope and channel erosion, and downstream deposition. While there have been numerous studies of these processes at the hillslope scale, 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 four years to quantify valley bottom changes in two ~15 km2 watersheds, Skin Gulch and Hill Gulch, after the June 2012 High Park fire in northern Colorado and followed by a large mesoscale flood 15 months later. The objectives were to: 1) quantify spatial and temporal patterns of erosion and deposition throughout the channel network following the wildfire and subsequent flooding; and 2) investigate the extent to which these changes can be related to precipitation amounts and intensities, burn severity, and valley and basin morphology. Geomorphic changes were quantified using a DEMs of difference (DoD) approach for the channel network segmented into 50-m lengths. The DoDs show net sediment accumulation after the wildfire in the valley bottoms in both watersheds, with the greatest accumulation after summer thunderstorms in the first two years after burning in areas with wider and flatter valley bottoms. In contrast, the mesoscale flood caused large amounts of net erosion, with the greatest erosion in those areas with the greatest post-fire deposition. Volume changes for the different time periods were low but significantly correlated to, in order of highest correlation, contributing area, channel width, percent burned at high and/or moderate severity, channel slope, confinement ratio, maximum 30-minute rainfall, and total rainfall. 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.