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Evolution of scouring process downstream of grade‐control structures under steady and unsteady flows
Author(s) -
Lu JauYau,
Hong JianHao,
Chang KaiPo,
Lu TaiFang
Publication year - 2012
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.9318
Subject(s) - hydrograph , geology , flow (mathematics) , sediment transport , flood control , superposition principle , current (fluid) , unsteady flow , downstream (manufacturing) , series (stratigraphy) , geotechnical engineering , sediment , flood myth , mechanics , hydrology (agriculture) , geomorphology , engineering , physics , oceanography , paleontology , philosophy , theology , quantum mechanics , operations management
Abstract For many incised channels, one of the most common strategies is to install some hard structures, such as grade‐control structures (GCSs), in the riverbed to resist further incision. In this study, a series of experiments, including both steady and unsteady flow conditions, were conducted to investigate the scouring process downstream of a GCS. Three distinct phases, including the initial, developing and equilibrium phases, during the evolution of scour holes were identified. In addition, a semi‐empirical method was proposed to predict the equilibrium scour‐hole profile for the scour countermeasure design. In general, the comparisons between the experimental and simulated results are reasonably consistent. As the studies on temporal variation of the scour depth at GCSs caused by floods are limited, the effect of flood hydrograph shapes on the scour downstream of GCSs without upstream sediment supply was also investigated experimentally in this study. Based on the dimensional analysis and the concept of superposition, a methodology is proposed to simulate the time evolution of the maximum scour depth downstream of a GCS for steady flows. Moreover, the proposed scheme predicts reasonably well the temporal variations of the maximum scour depth for unsteady flows with both single and multiple peak. Copyright © 2012 John Wiley & Sons, Ltd.