Overland-Flow Resistance Characteristics of Nonsubmerged Vegetation
Publication: Journal of Irrigation and Drainage Engineering
Volume 143, Issue 8
Abstract
In order to discover the resistance characteristics of overland flow with vegetation cover, indoor drainage experiments with six slopes, seven flow discharges, and five degrees of vegetation cover are systematically studied based on the basic theories of hydrodynamics and hydraulics. The experimental results show that the overland flow index of nonsubmerged vegetation gradually increased from 0.333 to 0.845 as the degree of vegetation cover increased. Moreover, the relationship between the flow resistance, water depth, and Reynolds number did not present a monotonic increasing or decreasing tendency, but depended on the vegetation cover. When the degree of vegetation cover was lower than the critical value, the flow resistance coefficient decreased with increasing water depth and Reynolds number, whereas the opposite tendency was found when the degree of vegetation cover was greater than the critical value. The resistance coefficient gradually increased with increasing vegetation cover when the flow discharge was constant. Moreover, the increasing rate became steeper as flow discharge increased. The prediction formulae of average velocity and the resistance coefficient are proposed, and predicted results agree with corresponding experimental data. This conclusion is of scientific significance both in understanding the mechanisms of flow retardation and sand fixation by vegetation as well as in guiding the implementation of ecological restoration projects.
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Acknowledgments
Yong Peng’s work for this paper is much appreciated. The authors would like to thank the financial support of Open Funding (Grant No. 10501-1206) and Director Funding (Grant No. A314021402-1619) from the Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Water and Soil Conservation, Chinese Academy of Sciences and Ministry of Water Resources, China; the National Natural Science Foundation of China (Grant No. 51579214); and the Fundamental Research Funds for the Central Universities (Grant No. Z109021564).
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Published In
Journal of Irrigation and Drainage Engineering
Volume 143 • Issue 8 • August 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Oct 9, 2014
Accepted: Feb 7, 2017
Published online: May 10, 2017
Published in print: Aug 1, 2017
Discussion open until: Oct 10, 2017
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