The water-level fluctuation zone of Three Gorges Reservoir — A unique geomorphological unit

Three Gorges Reservoir (TGR) has provoked a series of unprecedented environmental problems, many of which are related to the transitional area between the base and capacity water levels of the reservoir, commonly referred to as the water-level fluctuation zone. We proposed here that this zone serves as a unique geomorphological unit playing an important role of influencing the life of the TGR and named it as the TGR disturbance zone because it has been intensively interrupted by various human activities. Based on its geomorphological characteristics, we divided this zone into three types that have hillside profiles with distinct shapes and gradients, grain components and sizes, and land uses. Although the three types of the zone have experienced the same set of geomorphological processes under the new annually cyclic hydrological regime, their responses and the associated morphologies are distinguishable. Thus we depicted them separately. Accompanied with these processes are geochemical and biological processes that bring about exacerbated pollution and destroyed ecosystem in this zone. We elaborated these problems and indicated the potential research directions toward fully understanding the complex geomorphological, geochemical, and biological processes prevalent in the zone.