Lu, Chi (2016-12). Riverine and Sediment Processes in the Yangtze River Estuary-modeling and Validation. Master's Thesis.
The sediment flux from the Yangtze River into the estuary area decreased during the past three decades and the operation of the world's largest hydropower project, Three Gorges Dam (TGD), made this situation much more severe. In the delta area, another project called Deep Water Navigation Channel was also completed in 2011. To investigate hydrodynamic and sediment transport processes, and document the impact of the Three Gorges Dam and the Deep Water Navigation Channel on estuarine hydrodynamics and morphology changes, we used the Delft3D flow module. Several islands and shoals in the Yangtze Estuary region were located near Deep Water Navigation Channel (DNC) and their morphological changes were tightly coupled with the sediment flux from the Yangtze River. The evolution of the geometry and elevation of these islands and shoals in the river are used as metrics to gauge the effect of the manmade changes to the Yangtze River Delta, as well as predict future changes and effects. Parameters such as cumulative erosion/sedimentation, 1-D transect profile, current and sediment mass per area are analyzed. Results show that Jetties built in the DNC project will slow down the current velocity inside the deep navigation channel and will induce a new pattern of local sediment transport, causing more sediment deposition inside the channel. The reduced sediment flux caused by the completion of TGD will decrease the available sediment mass on the bed of the Yangtze River Estuary and lead to coastline erosion of the islands and shoals in the Yangtze River Estuary in the future.