Impacts of the TGP project on the yangtze river ecology and management strategies

TGP project - the Three Gorges Project on the Yangtze River - is the largest hydro-project in China. This paper outlines the environmental and ecological impacts of the project. Cumulative sedimentation in the reservoir will reach an equilibrium in 100 years with a total volume about 16 billion m³The planned Xiangjiaba and Xiluodu reservoirs, which will be located at 1020 km and 1180 km upstream of the TGP dam, can be used to trap sediment and thus reduce the sedimentation rate of TGP reservoir in the first 90 years. Experimental studies showed that impoundment of TGP reservoir will cause sediment deposition at the apron of the Chongqing harbor and even change the stem flow from the west channel to the east channel. Building spur dykes and groins to regulate the flow can solve the problem. Calculation with 1-D models show that the released water from the dam will scour 2.5 billion tons of sediment from the downstream channels in 40 years, which will result in channel degradation. The flood stage will then be reduced by about 3m at Shashi and 0.75m at Wuhan for a flood of discharge 30,000m³/s. Studies indicate that the reservoir will not necessarily cause earthquakes, but will induce more landslides, which will threaten little the safety of the dam. It is reported that the impoundment of the reservoir so far has not obviously affected the water quality. The reservoir operation will change the hydrologic conditions, which may affect the life cycle and habitats of fishes and reduce the fishery harvest. The regulation of the flow for power generation and flood control may change the fluvial processes and some meandering and braided sections may become unstable, which will undermine the habitats of some endangered species. The longer the time of channel bed stability, the more species of benthic invertebrate may live and propagate on the riverbed. The number of benthic invertebrate will reduce because the erosion and sedimentation will make the channel bed unstable. New resettlement policy has been implemented with overall arrangements for production and living conditions for the emigrants. The farmland to be inundated would be about 23,000 hectares. Experiments in the reservoir area indicate that about 27,000 barren slope-land may be transformed into a terraced citrus orchard and it is able to turn out an output value equal to as much as those by the inundated land.