Journal of Watershed Management Research

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Zamani M, Rabiefar H, Rostami M. (2021). Numerical and Experimental Investigation of the Effect of Spur Dikes Placement Position on the Hydraulic and Erosion Conditions of Lateral Intakes. jwmr. 12(24), 287-297. doi:10.52547/jwmr.12.24.287
URL: http://jwmr.sanru.ac.ir/article-1-1114-en.html

Extended Abstract
Introduction and Objective: Intakes are structures that are used to divert water from a river or canal. Optimizing the performance of intakes and increasing the inflow to the intake, while controlling the sediment bed of the canal in terms of erosion and sedimentation has been one of the topics of water engineering. The use of spur dikes is effective in modifying the flow pattern, controlling erosion and transferring sediment to the intake. The purpose of this study is to use spur dikes to increase the inflow to the lateral intake, in a way that causes the least turbulence, erosion and sedimentation.
Material and Methods: In order to perform the experiments, a rectangular channel with a length of 15 meters and a width of 1.5 meters with a fixed slope was used as the main channel. Lateral intake is a rectangular canal with a width of 0.6 and a length of 5 meters at an angle of 90 degrees to the main canal, at a distance of 10 meters from the beginning of the main canal. The model without spur dike was considered as a control model and in other models, the spur dike is located upstream of the intake, upstream in front of the intake, downstream in front of the intake and also as a series of spur dike upstream and in front of the intake. The laboratory models were modeled in FLOW-3D software and calibrated based on laboratory results and data.
Results: Examination of laboratory results showed that the condition of the spur dike at the downstream and in front of the intake has the best scouring results and branching ratio and increase of 66 and 41% at 40 and 60 liters per second, respectively, for branching flow ratio Shown to the control model. According to the results of laboratory models, the model was selected as the best model and modeled numerically with the location of the spur dike in the downstream and in front of the lateral intake (the position of No. 4). Validation of the results of numerical and laboratory models in the hydraulic values ​​of water flow points (R²=0.95) and the number of bed points (R²=0.74) showed that the acceptable accuracy of the numerical model and analysis performed by Flow3D software. Then, first by changing the distance and then by changing the length of the spur dike in the position of No. 4, the numerical model was examined and the best distance of the spur dike, a distance of 58% of the width of the intake and the best length of the spur dike, a length of 30% of the channel width The original was calculated.
Conclusion: This study showed that the use of spur dike downstream and in front of the intake in appropriate dimensions can not only increase the ratio of inlet flow to the intake, but also reduce the scouring of the canal bed, as a result of the use of these spur dike in lateral intake of canals And rivers are recommended.