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Designing a Total-Load, Stream-Flow Sampler

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  032299,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.14979) @2003
Authors:   John A. Replogle
Keywords:   sediment sampling, watershed monitoring, total-load sampling, bed load sampling, suspended-load sampling, stream-flow measurement, flow measurement

Total load sampling of stream sediments is of particular interest in forest-fire areas because of the impact of increased erosion on reservoirs and the need to evaluate imposed watershed treatments. Total-load sampling has been a perpetual problem in sediment monitoring. Usually a combination of bed load sampling devices, suspended load suction samplers, and some kind of flume for total flow rate, is used. A total-load sediment sampler that can perform all three of these functions is proposed. It requires installation in sites that can provide an over fall height about equal to the maximum stream flow depth. The concept is based on a long, wide, and moving conveyor belt, with slots in the belt, onto which the stream to be sampled discharges. All flow drops through the slots, and with equal sized slots each must catch a similar proportion of the total flow. Hence, only one slot needs to be collected. A test rack with several slots, representing a small section of the total conveyor belt, is proposed to be traversed left and right through the falling nappe. Tests of this sampling assembly rack indicated that its constructed width is related to the channel depth and the sum of the slot openings. When the rack slot-width sum is more than half the channel over fall depth, the system under sampled from 0% to 2 % but when it is less than one-third of the over fall depth, the system under sampled by over 8%. Design parameters are proposed along with specific construction details.

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