Decadal link between longitudinal morphological changes in branching channels of Yangtze Estuary and movement of the offshore depo-center

In estuaries, the morphology of inland and offshore areas usually evolves synergistically. This study examines the decadal link between longitudinal changes in morphology of branching channels and movement of the offshore depo-center (where sediment deposition rate is maximum) of the Yangtze River estuary, under intense human interference. Integrated data analysis is provided on morphology, runoff discharge, and ebb partition ratio from 1950 to 2017. Channel-volume reductions and change rates between isobaths in branching channels reflect the impact of estuarine engineering projects. Ebb partition ratio and duration of discharge ≥ 60 000 m3 s-1 act as proxies for the water excavating force in branching channels and runoff intensity. It is found that deposition occurs in the lower/upper sub-reaches (or further downstream/upstream channels) of the inland north/south branching channels, and the offshore depo-center moves southward or southeastward, as runoff intensity grows; the reverse occurs as runoff intensity declines. This is because the horizontal circumfluence in the Yangtze estuary rotates clockwise as ebb partition ratios of the north/south branching channels increase/decrease for increasing runoff, and conversely rotates anticlockwise for decreasing runoff. Land reclamation activities, the Deepwater Channel Project, and the Qingcaosha Reservoir have impacted greatly on longitudinal changes of morphology in the North Branch and the South Passage and on ebb partition ratio variations in the North/South Channel and the North/South Passage. Dam-induced runoff flattening has enhanced deposition in the upper/lower sub-reaches of the north/south branching channels and caused northward movement of the offshore depo-center, except in areas affected by estuarine engineering projects. Dam-induced longitudinal evolution of branching channel morphology and offshore depo-center movement will likely persist in the future, given the ongoing construction of large cascade dams in the upper Yangtze and the completion of major projects in the Yangtze estuary

Three Gorges Project: Effects of Resettlement on the Environment in the Reservoir Area and Countermeasures

Environmental problems resulting from human displacement and resettlement are considered to be secondary impacts of hydro projects. There is a significant gap in knowledge concerning the environmental consequences of resettlement of the Three Gorges project (TGP), China. This study examines critical environmental problems associated with the TGP resettlement. It reveals that the contradiction between the land inundation and demand for land in resettling rural residents is a critical environmental issue. On the positive side, countermeasures that are discussed include: engineering works for farmland protection, developing eco-agriculture, reforestation and constructing a green belt in the peripheral zone of the reservoir, and adjustments to resettlement policy. © Springer Science+Business Media, LLC 2006.Yan Tan, Fajun Ya