Comprehensive Assessment Of The Three Gorges Project's Impact On The Eco-environment In Reservoir Area

The Three Gorges Project(TGP) is a far-reaching impact of hydraulic and hydropower project. Eco-environment of the reservoir area will be inevitably brought about a lot of the impact by the project construction and its water storage.It is very concerned about these issues.In this study,based on the characteristics of eco-environmental factors and the collection of data of the study(1998～2007),it was used the comprehensive qualitative & quantitative evaluation methods to be combined with influence analysis & present situation evaluation.By this method,the quality of the eco-environment of three gorges reservoir area was be assessed about before and after TGP construction.Specifically,a impact analysis was firstly done by a comparative analysis and ecological carrying capacity analysis for the indicators,such as the local climate(temperature,relative humidity,wind speed, precipitation,evaporation,fog days),land-use change,soil erosion,animal and plant diversity in the reservoir area,hydrologic and sediment and water(potassium permanganate index,total nitrogen,total phosphorus,ammonia nitrogen,volatile phenol,oil pollutant,heavy metals content of Pb and Hg),et al. And then present situation evaluation of the eco-environment of three gorges reservoir area was be assessed by combined with analytic hierarchy process(AHP) and fuzzy comprehensive evaluation, which had independently done the evaluation and then mutually verified the evaluation results.Finally, a short-term prediction and analysis on the eco-environmental impact was carried on for 2008～2012.Based on these methods,the study had come to some of the following conclusions.And it was wished to not only explain the impact to the three gorges reservoir area by TGP,but also give some advice on the theoretical basis and evaluation of technical system guidance for the eco-environment construction and protection in the future of the three gorges reservoir area.(1) By the analysis of the indicators about the impact of the eco-environment,the study found that the construction of TGP has brought indeed unavoidable impact on the reservoir area for the ecological environment.The impact shows for not only in the reservoir area for terrestrial and aquatic biodiversity, local climate,land-use structure,hydrologic and sediment,such as the direct impact,but also indirectly on soil erosion,ecological carrying capacity,water quality.Through man-made eco-environmental governance,the ecological state of the environment is improving,and the impact of the reservoir area by TGP has been reduced in the minimum.(2) At present,it is mainly seen in the following aspects for the eco-environmental impacts of the three gorges reservoir area by TGP:Positive impacts are included that aquatic biodiversity has been enriched,soil erosion of the reservoir area have been effectively controlled,sediment content and runoff range are gradually decreasing,and water quality of main stream is being improved.Negative impacts are included that terrestrial ecosystems,fish stocks,ecological carrying capacity and tributary water quality in the reservoir area had been becoming a degree of recession,reduction and deterioration.Less impact is included that animal habitats and its scope of activities are only changed but their number seldom changed,and it is same as the change of the reservoir area of the basic pattern of land use.In addition,the construction of TGP fundamentally changed the site conditions in the reservoir area, which has more far-reaching impact on the local climate in this area.In the main factor of the local climate,air temperature,relative humidity,wind speed,precipitation and fog have been on decline, while evaporation has increased.It appeared a transformed trend to the local climate that it is being changed from the rivers type to lake one,gradually.(3) By using of AHP and fuzzy evaluation method to independent evaluation 2000's and 2007's eco-environment quality,it was showed that the eco-environment impact of the three gorges reservoir was weak and not obvious,while it was better in 2007 than 2000.By AHP method,the eco-environment ratio was 1.034 for 2007 to 2000.The value of comprehensive evaluation by fuzzy evaluation was close in 2000 and in 2007,which was 2.501 in 2000 and 2.337 in 2007.In addition,the assessment used the method of two types of models combined with independent evaluation and interactive verification, which could avoid some errors compared with one method's evaluation.It has higher feasibility, credibility and accuracy.(4) According to the short-term forecasts(2008～2012) on the impact of the 13 eco-environmental factors of the three gorges reservoir,including the local climate,arable land,hydrologic and sediment, water quality and the population in the reservoir area,et al.,through the neural network method,it was showed that with maintenance for the measures to the eco-environment management and protection,the eco-environment impact to the reservoir area by TGP has being gradually weakened,and eco-system of the reservoir area has being gradually restored.