三峡工程的能值足迹与生态承载力

Emergy Footprint and Ecological Capacity of the Three Gorges Project

应用水电工程的能值足迹模型,构建生态盈余(EP)、生态影响系数(γ)、生态平衡时间(Te)、生态盈余时间(Ts)参数,实现对三峡工程建设期和运行期生态效应的定量评价。研究表明:1)三峡工程建设期的能值足迹占用为5.92×10~8hm^2,水库移民是其主要方面(占56.12%),做好移民工作是三峡工程成败的关键。2)2014年,三峡工程的生态承载力供给为4.38×10~7hm^2,对社会、经济和环境贡献最大的是水力发电(占59.48%),其次是库区航运、对下游的补水和防洪效益,分别占15.45%、9.74%和7.36%。3)库区水质污染是三峡工程运行期的最大影响因素,每年的能值足迹占用为1.04×10~7hm^2(占70.94%),其中,COD、TN、TP和Hg分别占28.7%、26.50%、5.75%和5.37%;其次是生态及地质灾害等的防治(占21.68%);泥沙淤积的影响比预计的小(占6.20%)。控制入库水污染物并对已经入库的水污染物采取减量化措施,是控制和减小三峡工程对社会、经济和环境影响的关键。4)在维持2012—2014年平均投入产出、合理使用年限为150 a的情况下,三峡工程将在2026年实现生态平衡;生态影响系数为0.15,影响等级为Ⅰ级,三峡工程对社会、经济和环境的影响是积极有利的。

Four parameters, namely, ecological profit（EP）, ecological impact coefficient（γ）,ecological balance time（Te） and ecological surplus time（Ts）, are calculated based on the emergy footprint model to quantitatively evaluate the ecological effect of the Three Gorges Project（TGP） during construction period and operation period. Studies have shown that： 1） The emergy footprint of TGP construction is 4.99 × 10^8hm^2, and the reservoir resettlement is the main aspect, accounting for 56.12%. Migration is the key issue having respect to the success or failure of the TGP. 2） The largest contribution of the TGP is hydroelectricity, whose ecological capacity is 4.53 × 10^7hm^2 in 2014, accounting for 59.48%, followed by the shipping（15.45%）,replenishment to downstream（9.74%） and flood control benefit（7.36%）. 3） Water pollution in the Three Gorges Reservoir area is the largest influencing factors during the project operation,whose emergy footprint is 1.04 × 10^7hm^2· a^（-1）, accounting for 70.94%. Wherein, COD, TN, TP and Hg account for 28.7%, 26.50%, 5.75% and 5.37%, respectively. The second largest one is the prevention and control of ecological and geological disasters（21.68%）. The influence of the sediment deposition is smaller than expected（6.20%）. Controlling the injection of pollutants and decrease the injected pollutants are the key measures to control and reduce the impact of the TGP on the society, economy and the environment. 4） The TGP will achieve ecological balance in 2026 based on the average input- output from 2012 to 2014 and the reasonable service life of 150 year. The ecological impact coefficient is 0.15 at the level I of impact. There is a positive and beneficial influence of the TGP on the society, economy and environment.