Study On Ecological Security Assessment Of Hongze Lake

Lake ecological security refers to a constant state of the integrity and eco-health of lake under the influnce of the activities of human being, which steadily provides the ecological service function for human and avoids ecological catastrophe. Hongze lake is an important regulating reservoir of the Eastern Route of South-to-North Water Transfer Project as the fourth largest fresh-water lake in China, not only the water quality of Hongze lake declined, but also the function of ecosystem degraded with the rapid growth of the economy and the rapid urbanization for decades. Thus, the ecological service function of Hongze lake such as fishing spawning areas, habitats, swimming and entertainment venues, etc had been seriously damaged,and the ecosystem health is now being threatened. In this paper, we chose the Hongze lake and its watershed as the research object. In order to make an integrated quantitative evaluation on the ecological security of Hongze lake, the evaluation was conducted from four aspects and a cross-validation on the basis of the lake ecological security evaluation method by historical data collection and field investigation, that is “4+1” evaluation model, including lake water ecosystem health, ecosystem service function, ecological catastrophe and socioeconomic development. The main conclusions in this paper are as follows:(1) The value of ecological security index(SESI) of Hongze lake was 62.80 in 2012, the status of ecological security was still in its "safey" level. In recent years, the ecological security of Hongze lake was in a relatively stable state, however, it had obviously decreased compared with the status in 1980 s.(2) The integrated ecosystem health of Hongze lake overall was in a good condition and the medial level, but the comprehensive ecosystem health index showed a decreasing trend.(3) The value of ecosystem service function of Hongze lake retained only 75% compared with Compared with the 1980 s, the functions of ecological products supply and ecosystem regulation showed a trend of deterioration. In addition, the functions of non-point source pollutants interception and water quality purification of Hongze lake were weaker than ordinary water-carrying lakes and wetlands.(4) The upriver water quality of Hongze lake has a decisive impact on the incidents of ecological disaster of Hongze lake. Local area of Chengzi lake has the condition of breakout of algal bloom affected by the hydrological regimes, and there is a risk of catastrophe certainly for the ecological environment of this lake(5) The comprehensive pressure index of Hongze lake was level three, which indicated that the basin system structure is rather sensitive.The impact of socioeconomic development will bring heavy pressure which has nearly reached the ecological threshold to Hongze lake.(6) In order to improve the ecological security of Hongze lake, the pollution into Hongze lake and its watershed must be controlled strictly, the protection of wetland must be strengthened, the greenization of industry transformation and upgradation must be implemented,the development of ecological fishery and the comprehenseive management of watershed ecological security must be carried out.