Effectiveness of grade-control structures in reducing erosion along incised river channels: the case of Hotophia Creek, Mississippi |
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| Authors: | Andrew Simon Stephen E Darby |
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| Institution: | 1. Dept. of Geography and Anthropology, Louisiana State University, 227 Howe-Russell-Kniffen Geoscience Complex, Baton Rouge, LA 70803, USA;2. Dept. of Geography and Geographic Information Science, University of Illinois, Urbana-Champaign, 131 Computer Applications Building, 605 East Springfield Ave, Champaign, IL 61820, USA;3. US Dept. of Agriculture, Agricultural Research Service, National Sedimentation Laboratory, P.O. Box 1157, 598 Mc Elroy Drive, Oxford, MS 38655, USA;4. Department of Geology, University of Illinois, Urbana-Champaign, 605 East Springfield Ave, Champaign, IL 61820, USA;5. Department of Geography and Geographic Information Science, University of Illinois, Urbana-Champaign, 605 East Springfield Ave, Champaign, IL 61820, USA;6. Department of Mechanical Science and Engineering, University of Illinois, Urbana-Champaign, 605 East Springfield Ave, Champaign, IL 61820, USA;7. Ven Te Chow Hydrosystems Laboratory, University of Illinois, Urbana-Champaign, 605 East Springfield Ave, Champaign, IL 61820, USA;8. Dept. of Civil and Environmental Engineering, University of Pittsburgh, 1249 Benedum Hall, Pittsburgh, PA 15261, USA;9. Dept. of Civil and Environmental Engineering, Ven Te Chow Hydrosystems Laboratory, University of Illinois, Urbana-Champaign, 2535 Hydrosystems Laboratory, 301 N. Mathews Ave, Urbana, IL 61801, USA;1. Laboratory of Management and Control of Mountainous Waters (Lab MCMW), Department of Forestry and Natural Environment Management, Eastern Macedonia and Thrace Institute of Technology (EMaTTECH), Drama Annex, 1st km Drama-Mikrohoriou, Drama 66100, Greece;2. Department of Natural Resource Ecology and Management, Iowa State University, 339 Science II, Ames, IA 50011, United States;1. Department of Civil Engineering, National Chiao Tung University, 1001, University Road, Hsinchu 30010, Taiwan;2. Water Resources Planning Institute, Water Resources Agency, MOEA, 1340, Jhong-jheng Road, Wu-fong, Taichung 41350, Taiwan |
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| Abstract: | Herein, we undertake a geomorphological analysis in which spatial and temporal trends of bed and bank erosion along an 18-km length of Hotophia Creek, Mississippi, are estimated for the period between 1961 and 2050. The evaluation was undertaken for two scenarios of channel response to channelization during 1961–1963. One scenario represents the ‘actual’ response of the channel and includes the effects of installing a series of grade-control structures (GCS) between 1980 and 1996, while the other represents a hypothetical scenario in which the channel is left to adjust naturally. This allows the effectiveness of GCS in reducing in-channel erosion to be assessed. The analysis relies on the availability of channel survey data to develop empirical bed and bank response models for each adjustment scenario, supplemented by bank stability modelling to predict future rates of bank erosion. Results indicate that channel erosion rates decline nonlinearly with respect to time since 1961, for both adjustment scenarios. However, by the year 2050, the “with” GCS adjustment scenario results in the cumulative removal of some 663,000 (9%) extra tonnes of sediment relative to the “without” GCS scenario. Most (63%) of this excess is derived from enhanced bed erosion during 1976–1985 and 1985–1992, with the remainder derived from increased bank erosion during 1985–1992. Detailed analysis of the patterns of erosion and deposition, and their association with the GCS, provides evidence to support the view that GCS installed along Hotophia Creek have, for the most part, been ineffective in reducing channel erosion rates. This is because the GCS were installed too late to prevent bed degradation, caused by the 1961–1963 channelization, migrating upstream. In addition, some structures have disrupted the downstream transmission of bed material from eroded reaches upstream, exacerbating bed degradation and bank erosion in incised reaches downstream. |
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| Keywords: | Hotophia Creek Grade-control structures Sediment yield Erosion control Applied geomorphology |
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