ANALYSIS OF CHARACTERISTICS OF SEVERAL BENDS ON SIDOAN RIVER

Researching the behavior of the river. Especially at the bend, where the morphology of the river is not always straightforward. Flow velocity high water and grinding at river bends occur at different points. This research was conducted on five adjacent bends on the Sidoan River section. This study examined the condition of riverbed sediment, knowing the stability of riverbed sediment granules based on shearing velocity, and stability of riverbed sediment granules based on shear stress. The method used in this study is geometric measurement. Q50 discharge calculation. produces hydraulic simulation. d50 sediment diameter. HEC-RAS software simulation and Shields graphs analysis. The results of the study on five bends for Q50 discharge are the condition of the riverbed in five bends all moving, the critical shear velocity relationship and flow depth are directly proportional, the highest condition at bend 2, otherwise the lowest condition at bend 3. The relationship between particle dimensions and shear velocity is inversely proportional to the value of sliding velocity. if the particle dimensions are small then the large shear stress occurs at bend 5 and vice versa, the dimensions of large particles then the small shear velocity occurs at bend 4, sliding velocity is directly proportional to the shear stress. The highest critical shear stress at bend 2, while the lowest condition at bend 4, the greater the radius of the bend the scouring was deeper.