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Title: Flow Measurements on Steep Slopes and in Sediment-Laden Flows Using the Drop-Box Weir

item Bonta, James - Jim

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/22/2007
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Large sediment loads and large particles from unprotected slopes, mined lands, construction areas, and range lands under high intensity rainfalls result from high intensity rainfalls. Flow-measuring devices will become clogged with sediment in a single event, resulting in the loss of runoff and sediment records. Also, in steep channels, inaccurate flow measurements are likely using conventional flow-measuring devices. The drop-box weir (DBW) was developed to overcome the problems encountered in sediment-laden flow measurement. The weir creates turbulence and entrains sediment as it passes sediment-laden flow through the weir. The weir was developed in the 1960s, but it is not well known, and it has not been widely used because of insufficient information on its performance, limited field conditions for its use, and unclear presentation. Yet it is only one of two devices suitable for obtaining flow records with large sediment concentrations and large particles (including large rocks). Recent hydraulic studies on modified version of the DBW have extended the utility of the DBW from watershed with small channel slopes to small rectangular runoff/erosion plots and steep channels. Furthermore, the low-flow rating (previously not available) has been developed. Water samplers that have been designed for use with the DBW are presented along with research needs.