Nine watersheds in the Colorado Front Range with steep bedrock channels were used to test the accuracy of paleohydraulic reconstruction of large flash floods using boulder deposits. In each basin, coarse boulder deposits of the large flash floods were identified, and three axes of the five largest boulders were measured, along with at least two profiles of the valley cross section. A simple arithmetic average of two theoretical and two empirical relationships was used to estimate average flood velocity using boulder size and shape. Average depth was estimated as the arithmetic average of four values computed from the Manning equation, a regression equation for boulder size and unit stream power, a relative smoothness equation, and a modified Shield's relationship. The appropriate flood width for the estimated average depth was found by iteration, using the valley cross sections.- from Author
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Paleohydraulic reconstruction of flash- flood peaks from boulder deposits in the Colorado Front Range.