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Wildfire can significantly alter the hydrologic response of a watershed to the extent that even modest rainstorms can produce dangerous flash floods and debris flows. The USGS conducts post-fire debris-flow hazard assessments for select fires in the Western U.S. We use geospatial data related to basin morphometry, burn severity, soil properties, and rainfall characteristics to estimate the probability and volume of debris flows that may occur in response to a design storm.
Many difficult problems in river mechanics may have stemmed from inadequate understanding of the multiplicity and interaction of fluvial processes. Some of the problems may have been solved, but in a very simplified, approximate way. Many efforts have been directed, but without apparent success, to fully account for the causes, occurrences, and mechanisms of catastrophic events, such as flash floods, debris flows, and channel changes resulting from torrential storms, sudden snow or glacier melt, dam break, volcanic eruptions, and earthquakes. Such failures may be partially attributed to the deficiency and incompleteness of existing empirical formulas (or models) representing the relationships between various processes...
Categories: Project;
Tags: Debris Flows,
Flash Floods,
Geomorphology and Sediment Transport,
Rivers and Streams,
Watershed Studies
These data were compiled from sampling pre-dam flood terraces and sand bar deposits of the Colorado River in Glen Canyon between Glen Canyon Dam and the Paria River confluence. This includes sand deposits from the 2008, 2012, 2013 and 2014 high flow experiments (HFE) in Marble Canyon. Sand sources from these locations were sampled in September/October of 2013 and 2014. Also, samples of suspended sediment from a selection of Paria River flash floods that preceded the 2013 and 2014 high flow experiments were collected. The suspended sediment samples were wet sieved to separate the <63-micron fraction at the Grand Canyon Monitoring and Research Center. A Niton XL3-t 955 portable XRF was used to measure the elemental...
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