ASCE will be sunsetting the Civil Engineering Database (CEDB) in the coming months. We encourage you to start using the ASCE Library to perform content searches. In the ASCE Library, you can save your search results as well as receive email content alerts when new content relevant to your area of interest is published. Try it out today at https://ascelibrary.org.

 

Differentiation of Debris-Flow and Flash-Flood Deposits: Implications for Paleoflood Investigations

by Christopher F. Waythomas, U.S. Geological Survey, Anchorage, United States,
Robert D. Jarrett, U.S. Geological Survey, Anchorage, United States,



Document Type: Proceeding Paper

Part of: Hydraulic Engineering

Abstract:

Debris flows and flash floods are common geomorphic processes in the Colorado Rocky Mountain Front Range and foothills. Usually, debris flows and flash floods are associated with excess summer rainfall or snowmelt, in areas were unconsolidated surficial deposits are relatively thick and slopes are steep. In the Front Range and foothills, flash flooding is limited to areas below about 2300m whereas, debris flow activity is common throughout the foothill and alpine zones and is not necessarily elevation limited. Because flash floods and debris flows transport large quantities of bouldery sediment, the resulting deposits appear somewhat similar even though such deposits were produced by different processes. Discharge estimates based on debris-flow deposits interpreted as flash-flood deposits have large errors because techniques for discharge retrodiction were developed for water floods with negligible sediment concentrations. Criteria for differentiating between debris-flow and flash-flood deposits are most useful for deposits that are fresh and well-exposed. However, with the passage of time, both debris-flow and flash-flood deposits become modified by the combined effects of weathering, colluviation, changes in surface morphology, and in some instances removal of interstitial sediment. As a result, some of the physical characteristics of the deposits become more alike. Criteria especially applicable to older deposits are needed. We differentiate flash-flood from debris-flow and other deposits using clast fabric measurements and other morphologic and sedimentologic techniques (e.g., deposit morphology, clast lithology, particle size and shape, geomorphic setting).

Subject Headings: Solids flow | Flash floods | Floods | Debris | Sediment | Water discharge | Sediment transport | Colorado | United States | Rocky Mountains

Services: Buy this book/Buy this article

 

Return to search