Channel aggradation below Chew Valley Lake,Somerset, U.K. |
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| Institution: | 1. University of Nevada Reno, Department of Natural Resources and Environmental Science, Reno, NV, USA;2. U.S. Department of Agriculture, Agriculture Research Service, Great Basin Rangelands Research Unit, Reno, NV, USA;3. U.S. Department of the Interior, Bureau of Land Management, National Operation Center, Denver, CO, USA;1. British Geological Survey, Environmental Science Centre, Nicker Hill, Keyworth, Nottingham NG12 5GG, United Kingdom;2. Department of Civil Engineering, School of Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom;3. British Geological Survey (May – July 2016), Polytech Grenoble, 14, Place du Conseil National de la Résistance, 38400, St-Martin-d''Hères, France;1. MED_Soil Research Group, University of Seville, Spain;2. Soil Quality Department, Environment Agency — Abu Dhabi, P.O. Box 45553, Abu Dhabi, United Arab Emirates;3. Soils and Water Sciences Department, Faculty of Agriculture, Fayoum University, P.O. Box 63514, Fayoum, Egypt |
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| Abstract: | Variations of channel substrate composition are described for a regulated river which has experienced channel change since dam completion. Sediment samples were obtained using bulk (grab) sampling and freeze-coring. Data derived from the two methods are shown to differ. Bulk-sample data describe the bed surface layer; its grain-size variations are related to bedform. Freeze-core data describe the sub-surface structure and the fine size-grades.The gravel framework-supported substrate of the control reaches constrasts with the sand-dominated substrate of the aggraded reach, although in both cases the substrate coarsens upwards. In the former this relates to the development of a sand matrix within the gravel-framework substrate, and in the latter, sand-bed channel, to the progressive addition of a gravel component towards the surface which is related to the process of channel change. At the local-scale, bedform is shown to exert an important control on the character of substrate change induced by flow regulation. |
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