Study on effect of regulation engineering project on morphological evolution downstream of tidal barrage

Abstract:

Morphological evolution downstream of tidal barrage is sensitive to regulation engineering project. A set of methodology integrating verified tidal current model, sediment transport model and morphological evolution model was set up to quantify the influences of different stages of regulation engineering project in the Shuanglong Estuary on currents and morphological evolution. Results indicate that the changes of currents and morphological evolution are closely associated with partially deepened-widened channel and increased tidal influx. In general, increased wetted area in the upper estuary has intensified the asymmetry of flood-ebb current velocity and even induces recirculating flow. While fully regulation over the estuary with a fixed slope will increase tidal current velocity significantly and relieve the asymmetry of flood-ebb current velocity as well. Though increased tidal influx at the estuary acts a positive factor washing out the sediment in lower channel, sediment deposition occurs in widened section of the estuary due to the decreasing tidal current velocity, especially in recirculating flow region. Therefore, for enhancing the function of regulation project, releasing water from upper barriers and dredging regularly are also needed.