A Field Based Process Study of Subaqueous Hydraulic Jumps inDebris and Turbidity Flows

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An integrated, field based project will be carried out to: (a) continuously monitor subaqueous debris and turbidity flows for temperature, density, velocity, and travel distance in a reservoir environment; (b) study flow conversions of debris flows to turbidity currents, specifically by means of hydraulic jumps, and the role of bottom geometry in such conversions; and (c) correlate the characteristics of the flow with the nature of the sediment deposition/erosion processes, the bottom geometry, and other parameters governing the transport processes. The work will be conducted in conjunction with a project jointly funded by the U.S. Forest Service, the Los Angeles County Fire Department, and the L.A. Flood Control District, in which controlled fires, pollutant and smoke effects, sediment yields, and debris flows emanating from the burned areas are being studied. The site is the Lodi Canyon and Puddingstone Diversion Reservoir, located in the San Gabriel Mountains near Los Angeles, that has long hydrologic and sediment records, detailed geologic and geomorphic data available, a single sediment input source, a reservoir of manageable size, and other convenient characteristics and conditions. The results from this work will help increase the accuracy of predictions of the movement patterns and incidence of subaqueous debris and turbidity flows; the determination of threshold conditions; the probable travel distance of such events; and an assessment of both the ability of subaqueous hydraulic jumps to control the deposition of sediments; and the possible engineered use of these jumps to control the location of sediment during major flood events.