Assessment of Hydrodynamic Regime and Inundation Mode After Construction of Hydraulic Project in Quang Ngai Province

Before the construction of any hydraulic project, the flow regime should be ensured to have little effect on the banks and on the civil constructions downstream. From the data of nearby projects, the authors have carried out the numerical simulation of a low-head dam project on Tra Khuc river using the International River Interface Cooperative (IRIC). The calibration is conducted by comparing the simulation of the river in its natural state with actual measurement from surrounding stations and the results are shown to be acceptable. The model is tested on several scenarios of flooding, with a combined spillway (piano-key weir and gated ones) or without the structure. It is shown that the flow regime behind the piano key is very complicated, however, after a certain distance, flow streams of various directions and velocities combine into a considerably stable and uniform stream. Furthermore, compared to the natural state of the river, the water level after the construction of the low-head dam does not rise significantly and at the same time, the task of increasing the upstream water level is fulfilled.