University of Tabriz Water and Soil Science 2008-5133 28 1 2018 03 21 Numerical Investigation of the Effect of Groins and Bendway Weirs on Flow and Sediment Pattern Using Mike 3 Flow Model FM Numerical Investigation of the Effect of Groins and Bendway Weirs on Flow and Sediment Pattern Using Mike 3 Flow Model FM 159 171 7601 FA H Bigdeli-Tabar-Sahreini M.Sc. of water structures, Urmia University, Urmia, Iran M Hemmati Assistant Prof. of water engineering, Urmia University, Urmia, Iran H Ahmadi Associate Prof. of water engineering, Urmia University, Urmia, Iran V Naderkhanloo M.Sc. of water structures, Tarbiat Modares University, Tehran, Iran Journal Article 2018 07 01 Bendway weirs are important multi-purpose structures for erosion control and are implemented to control erosion, restore streams, and improve habitat. Investigation of the effect of weirs’s height on flow pattern and erosion and sedimentation by application Mike 3 Flow Model FM was the aim of this research. The used variables were three flow discharge rates of 120, 150 and 180 (l/s), three weir heights of 0.5y, 0.7y (submerge weirs) and 1.2y (spur) (y is the mean water depth). The length ratio (L/B) was kept constant during experiments (equal to 3 times of water surface width) as well, weir crest slope (flat crest) and weirs angle (60 degree) were also constant. The results showed that the maximum difference between experimental and simulation data of the maximum scour depth at the tip of weirs was about 7.6 %. So a good agreement was found between the model and experimental results. Furthermore, the results revealed that the bendway weirs were more efficient than groins in reducing the velocity magnitude, decreasing the scour at the outer bank side and in decreasing the sediment deposition at the inner bank side. On average, the velocity magnitude at the outer bank side decreased by 81, 85 and 70 % in weirs with heights of 0.3y, 0.7y and 1.2y, respectively. Generally, the results of this research showed that the weirs with a height of 0.7y had the most influence on protection of outer bank. Bendway weirs are important multi-purpose structures for erosion control and are implemented to control erosion, restore streams, and improve habitat. Investigation of the effect of weirs’s height on flow pattern and erosion and sedimentation by application Mike 3 Flow Model FM was the aim of this research. The used variables were three flow discharge rates of 120, 150 and 180 (l/s), three weir heights of 0.5y, 0.7y (submerge weirs) and 1.2y (spur) (y is the mean water depth). The length ratio (L/B) was kept constant during experiments (equal to 3 times of water surface width) as well, weir crest slope (flat crest) and weirs angle (60 degree) were also constant. The results showed that the maximum difference between experimental and simulation data of the maximum scour depth at the tip of weirs was about 7.6 %. So a good agreement was found between the model and experimental results. Furthermore, the results revealed that the bendway weirs were more efficient than groins in reducing the velocity magnitude, decreasing the scour at the outer bank side and in decreasing the sediment deposition at the inner bank side. On average, the velocity magnitude at the outer bank side decreased by 81, 85 and 70 % in weirs with heights of 0.3y, 0.7y and 1.2y, respectively. Generally, the results of this research showed that the weirs with a height of 0.7y had the most influence on protection of outer bank. https://water-soil.tabrizu.ac.ir/article_7601_2caf9ad8309559ca268adfcb9d82a81f.pdf