Abstract
The enhanced permeable groin is a novel eco-friendly and cost-effective technique for bank protection and restoration of meander bends. The behavior of bed deformations due to the distance between the structures has to be studied to design enhanced permeable groins in series properly. In this study, scour morphologies around enhanced permeable groins in series, characterized by four different distances and located in a 180° mild flume bend, for clear water conditions were investigated. The analysis indicated that scour geometrical patterns such as the maximum scour depth nearby the structures and the maximum deposition height between them are strongly affected by the distance between the groins. The results revealed that the maximum scour depth around the structures increases with the distance between structures, the scour holes develop towards the outer bank and create a series of pools that can lead to the bank collapse. All experiments, carried out with different structure distances, demonstrated that the location of thalweg effectively shifted towards the middle of the channel and near the inner bank for high and low particle Froude numbers, respectively. As a general result, a distance between enhanced permeable groins equal to four times the effective length of the structure is recommended for a 180° mild flume bend for the investigated particle Froude numbers. Finally, a general design guideline is presented to a proper design of enhanced permeable groins in series.
Highlights
Many of the rivers in nature take a meandering form, including arc-shaped intervals characterized by erosion at the outer banks and deposition of point bars at the inner-banks [1]
The maximum scour depth occurred near the end of the first enhanced permeable groin (EPG), and the maximum sedimentation height formed downstream of it
The present study experimentally investigated the effects of changes in the distance between enhanced permeable groins in series on bed topography in a 180◦ mild flume bend
Summary
Many of the rivers in nature take a meandering form, including arc-shaped intervals characterized by erosion at the outer banks and deposition of point bars at the inner-banks [1]. These experimental runs were carried out in a 180◦ mild laboratory flume bend for the clear water condition and using nine different combinations of permeable groin with triangular vane include three different effective lengths and three angles of the vane According to these experimental results, a single permeable groin cannot provide a proper sediment deposition zone near the outer bank to protect it from erosion while the single EPG is characterized by a good performance of the outer bank protection.
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