Abstract. The Three Gorges Dam (TGD), located in the main stream of the Yangtze River,
is the world's largest hydroelectric station in terms of installed power
capacity. It was demonstrated that the TGD had caused considerable
modifications in the downstream freshwater discharge due to its seasonal
operation mode of multiple utilisation for flood control, irrigation, and
power generation. To understand the impacts of the freshwater regulation of
the TGD, an analytical model is adopted to explore how the operation of the
TGD may affect the spatial–temporal patterns of tide–river dynamics in the
Yangtze River estuary. We evaluated the effect of the TGD by comparing the
changes in major tide–river dynamics in the post-TGD period (2003–2014)
with those in the pre-TGD period (1979–1984). The results indicate that the
strongest impacts occurred during the autumn and winter, corresponding to a
substantial reduction in freshwater discharge during the wet-to-dry
transition period and slightly increased discharge during the dry season. The
underlying mechanism leading to changes in the tide–river dynamics lies in
the alteration of freshwater discharge, while the impact of geometric change
is minimal. Overall, the results suggest that the spatial–temporal pattern
of tide–river dynamics is sensitive to the freshwater regulation of the TGD,
so that the ecosystem function of the estuary may undergo profound
disturbances. The results obtained from this study can be used to set
scientific guidelines for water resource management (e.g. navigation, flood
control, salt intrusion) in dam-controlled estuarine systems.
Impacts of Three Gorges Dam's operation on spatial–temporal patterns of tide–river dynamics in the Yangtze River estuary, China