Predicting bed load transport of sand and gravel on Goodwin Creek

Authors: Kuhnle, Roger; Wren, Daniel; Langendoen, Eddy

Submitted to: Journal of Hydro-environment Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2013
Publication Date: 6/1/2014
Citation: Kuhnle, R.A., Wren, D.G., Langendoen, E.J. 2014. Predicting bed load transport of sand and gravel on Goodwin Creek. Journal of Hydro-environment Research. 8(2):153-163.

Interpretive Summary: Knowledge of the rate of sediment being moved by the flow of water agricultural watersheds is necessary because sustainable management of agricultural watersheds requires that the sources and rates of sediment erosion, transport and deposition be known. In addition to depleting valuable topsoil and threatening buildings, bridges, and roads; erosion or deposition from stream channels may cause offsite sediment damages include filling reservoirs and reducing their capacity, filling channels and causing flooding, and degrading water quality and adversely affecting aquatic ecosystems. Physical, chemical, and biological sediment damage in North America has been estimated to exceed 16 billion dollars annually. Knowledge of the rates of sediment transport in streams and rivers is poorly known because accurate measurements and predictions are difficult and expensive to make. This study combines data collected on field and laboratory streams to test our ability to accurately predict the movement of sediment along the bottom of a stream or river. The study concludes that more accurate methods of determining the energy available to move the sediment are needed. The information provided by this study will result in the development of improved techniques to accurately predict the movement of sands and gravels along the bottom of a stream. This knowledge is necessary for land use managers and action agencies to successfully manage mixed land-use watersheds.

Technical Abstract: Bed load transport rates are difficult to predict in channels with bed material composed of sand and gravel mixtures. The transport of bed load was measured on Goodwin Creek, and in a laboratory flume channel with a similar bed material size distribution. The range of bed load transport rates measured in the laboratory channel were similar to those measured in the channel of Goodwin Creek, however, the shear stresses calculated on Goodwin were three times greater than in the laboratory channel for similar bed load transport rates. Much of this difference in shear stress was removed by applying the drag partitioning technique of Einstein, however, significant differences between the two sets of data remain. Predictions of bed load transport rates using two previously published transport relations were good for most flows for the laboratory data. For the Goodwin Creek bed load data, predicted transport rates were close to measured ones for low flows but diverged by an order of magnitude for high shear stresses. Improved methods of shear stress partitioning are needed to improve the performance of bed load transport relations on streams of this type.