Study On The Comprehensive Carrying Capacity Of Lake Based On Multi-objective And Group Decision-making

As a kind of peculiar natural systems, lake is one of the most important environment resources for humankind. Lake resources are abundant in China, but with the increase of population and the natural and artificial impact, contradictions between humankind and whole lake ecosystem have been increasingly outstanding, such as shrinking of the body of water, deterioration of water quality, coexistence of flood and drought disasters, degradation of lake functions, etc. The contradictions have restricted sustainable development of lake's region. Therefore, analyzing the carrying capacity of lake's water resources and even whole lake ecosystem is one of the key researches to maintain ecological functions of lakes and promote sustainable development in lake's region.On the basis of concluding and drawing lessons from the previous theory research achievements, this dissertation explores the concept of comprehensive carrying capacity of lake after analyzing the connotation of water resources carrying capacity and ecological carrying capacity. Through the researches including analysis on connotation and characteristics and determinants, establishment of assessment indicator system, establishment of multi-objective analysis model, improvement of multi-objective and group decision-making methods, positive analysis of Lake Poyang, the dissertation attempts to construct theory, model, methods and practice system to analyze comprehensive carrying capacity of lake. The key results are as follows.1. The concept of comprehensive carrying capacity of lake has been presented, that is, under the conditions of certain period and technology standard, with the principles of maintaining lake's healthy ecology, functions and sustainable development, considering the predictable influences of culture, institution and humankind's value choices, the scale of social and economic development and the population quantity with certain living quality in lake's region which the lake ecosystem is able to sustain.2. Taking four-level indicator system with cluster structure as a framework, the initial indicator system of comprehensive carrying capacity of lake includes indicators concerning carrying capacity subjects, indicators concerning carrying capacity objects, indicators concerning force-response. Based on the connotation and characteristics of comprehensive carrying capacity of lake, specific indicators have been set forth by using frequency-statistics approach and expert-consultation approach etc. Indicators concerning carrying capacity subjects have been divided into water resources segment, land resources segment and eco-environment segment. Indicators concerning carrying capacity objects have been divided into population segment, society segment, economy segment and segment of defending capacity of water disasters. Indicators concerning force-response have been divided into water resources segment, land resources segment, eco-environment segment and segment of defending capacity of water disasters.3. A dynamic input-output model based on demand structure has been first put forwards. And then it has been built up that multi-objective model of comprehensive carrying capacity of lake, which mainly comprises macroeconomic models, population models, water resources utilization models, water environment models, disasters analysis models and ecological carrying capacity analysis models etc. The macroeconomic models and population models are kernel of the multi-objective model. Models in equilibrium analysis between water demand and supply, models in water environment carrying capacity analysis and models in analysis of defending capacity of water disasters have reflected relationship between humans and water in the lake system. The ecological carrying capacity analysis models, which include analysis both on land occupation and ecological occupation resulting from production and living in lake's region, have reflected relationship between humans and land, relationship between humans and ecology in the lake system.4. Analysis of comprehensive carrying capacity of lake is a problem involved in multi-objective and group decision-making, which needs to resolve the conflict among objects for any decision-maker and to resolve the preference conflict among decision-makers. Therefore it has been presented that interactive Tchebycheff method based on group and multi-attribute decision-making. Then three types of methods in group and multi-attribute decision-making have been produced, i.e. method based on deviations maximizing models, two-phase decision-making method and method based on group's satisfaction degree of schemes.5. Comprehensive carrying capacity of Lake Poyang has been assessed. Based on input-output tables for Jiangxi province, direct consumption coefficient matrixes of Lake Poyang region in each year have been determined by applying 'RAS' adjusting method and key coefficient revising method combined with grey forecasting method and time series analysis method etc. It has been built up that dynamic input-output model based on demand structure for Lake Poyang region. By using the model, six sectors' gross output and value added in 2010 and in 2030 have been respectively forecasted under present economic growth pattern.According to related plans combined with application of forecasting models, the values of exogenous variables, coefficients and boundary in each year have been respectively set up for analysis of Lake Poyang's comprehensive carrying capacity. Using the theory, model and methods about 'analysis of comprehensive carrying capacity of lake based on multi-objective and group decision-making', the comprehensive carrying capacity of Lake Poyang has been respectively calculated in 2006, in 2010 and in 2030. The results show that the actual scale of population and economy in 2006 and the forecasting scale of population and economy in 2010 are both in the range of respective comprehensive carrying capacity of Lake Poyang, but the forecasting scale of population and economy is out of comprehensive carrying capacity of Lake Poyang in 2030.