Author(s): Jau-Yau Lu; Chih-Chiang Su; Jian-Hao Hong
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Keywords: Field experiment; Wash load; Bed material load; Bed load; Suspended load; Sediment transport equations
Abstract: Most rivers in Taiwan are relatively steep with rapid flows during typhoon or high flow seasons. A series of field experiments was conducted to collect sediment and hydraulic data using a portable measuring system with a suspended sediment sampler, a propeller-type velocimeter, and an ADCP during typhoons and high flows at the Tzu-Chiang Bridge of the lower Cho-Shui River, which is a major river with highest sediment yield in Taiwan. The main objectives of this study are to evaluate the applicability of the typical existing sediment transport formulas for the prediction of the sediment transport capacity, and to investigate the effects of cross-sectional geometry (i.e. channelization) and earthquake on the sediment load. The Cho-Shui River was an aggrading river with a high aspect ratio for the main channel near Tzu-Chiang Bridge during the years of 1980s. However, due to sand mining and the extreme flood events, it was channelized and has a relatively narrow main channel in the recent years. It was found that typical sediment transport equations gave reasonable predictions for the bed material load based on the data collected by Kuo et al. during 1984~1988. Nevertheless, most typical sediment transport equations can only correctly predict the bed material load for low sediment transport rates (less than about 1,000 tons/day-m) based on the data collected in the recent years. For very high sediment transport rates (greater than about 10,000 tons/day-m), most existing sediment transport equations far underestimate the bed material load.
Year: 2010