Water Resource Carrying Capacity Of Nansihu Lake

As a confluent area of various natural resources and man-made pollutants, it is difficult to exploit and manage the lake reasonably. As the largest lake of Shandong area, Nansihu Lake has a strategic significance because of its locating on the East Route Project of South to North Water Transfer. But water pollution, sullage deposition, diversity decrease of species are becoming severe since the 80th decade. These problems seriously affect the regional sustainable development.The author takes part in the project sponsored by natural science fund of Shandong Province (Y2004E01), the study of water safety of Nansihu basin, which makes the first research on the calculation of the water resource carrying capacity on Nansihu Lake. Based on the hydrological characteristics of the Nansihu Lake, the paper has a research on the water resources carrying capacity of the Nansihu Lake. The conclusions are as follows:(1) Taking water as the key factor, the paper analyzes the factors impacting on water resources carrying capacity in order to design the evaluation index system of water resources carrying capacity. Using the Fuzzy Synthetical Evaluation Method, the result indicates that the wetland ecological system of the Nansihu Lake is in sub-healthy state, whose degree of subjection is 0.475. The restriction on the water resources carrying capacity is serious from the sub-healthy state of the wetland ecosystem of the Nansihu Lake.(2) The basic characteristics of the regional water resources from the perspective of the balance between supply and requirement are as follows: In 2004, the total water resources and the available water resources in the Nansihu Lake were 268860×104m3 and 74998×104m3 respectively. The supply water was 30998×104m3, which was less than the total water resources and the available of the water resources. The tendency will hold on in 2010, 2020, 2030. There are various ecological and environmental problems in the Nansihu Lake, the main reasons of which are following the two aspects. Firstly, the regulating capacity of the Nansihu Lake is low. Secondly, the Nansihu Lake and related rivers are seriously polluted, most of which cannot satisfy with the demands of industry, agriculture and daily life.(3) Artificial ecology and natural ecology are brought into water resource carrying capacity. Then the regional water resource carrying capacity evaluation system has been built up. The evaluation system not only reflects the supply and requirement state of the regional water resource, but also shows the economy scale and the population scale carried by the water resource system. At the same time, it reflects the harmony extent among the water resource system, ecosystem, environment and socioeconomic system.(4)The water resources carrying capacity evaluation are composed of macroscopical calculation, monomial index calculation, the Analytic Hierarchy Process and synthetical index calculation. With the restriction of the available water resource, the max economy scales in 2004, 2010, 2020, 2030 are 24.430 billion RMB, 24.710 billion RMB, 45.809 billion RMB and 80.606 billion RMB respectively, while the max population scales are 3.8778×106, 3.9222×106, 3.5238×106 and 3.3586×106 respectively. With the restriction of the available water resource, the max economy scales are 10.098 billion RMB, 12.685 billion RMB and 47.360 billion RMB in 2004, 2010, 2020 and 2030, while the max population scales are 1.6029×106, 2.0135×106, 1.8302×106 and 1.9732×106 respectively. Synthetical index calculation is represented by carrying capacity index and harmony index. The carrying capacity index of the Nansihu Lake water resources in 2004, 2010, 2020 and 2030 are 1.0618, 0.9452, 0.9756 and 0.9716, while the harmony index are 0.7891, 0.8580. 0.9821 and 0.9925.The study on water resource carrying capacity of Nansihu Lake enriches the theory of water resource carrying capacity. It offers references for maintaining sustainable development of Nansihu Lake.