Backwater flow analysis due to the construction of the check dam series on Aie Dingin River using HEC-RAS

River profiles with steep slopes and loose-grained soil types will easily be carried away by river currents. One way to reduce the sediment rate is by constructing a check dam or a series of check dams. However, the effect of a series of check dams can influence each other, due to backwater flow. On the one hand, it is advantageous because the flow velocity is reduced, but it will raise the water level downstream of the dam and increase the height of the embankments and ponds. Based on the foregoing, an analysis of the backwater flow was carried out using HEC-RAS. The results obtained are that water backflow occurs in two water structures, namely the Koto Tuo and Koto Pulai check dams. The backwater flow is quite long, almost reaching the previous check dam. Where the length of the backwater flow is only up to the final threshold and it is advisable to observe local sedimentation behavior due to backwater flow.