Evaluation On Urban Water Ecosystem Services

Urban-rivers-lakes, as a kind of special ecological resource, are the foundation of supporting the system of whole life in the city. Urban water ecosystem, not only offers the foundation of production and life of mankind, but also has a function of maintaining urban ecosystem structure, ecological course and urban ecological environment. Because of quick urbanization, urban land use, as well as the quality, size, and arrangement of urban ecosystem, is evolving seriously, leading to the change of urban ecosystem value. This paper takes Nanchang, which is the central city of Poyang Lake Ecological Economic Zone, as an example. Based on the current researches of urban water ecosystem services, the article makes quantificational evaluation of urban-rivers-lakes ecosystem services.The main contents and results are as follows:The contents, structure, and classification system of urban water ecosystem services are preliminarily defined.By using Contingent Valuation Method, this paper makes static value assessment of water ecosystem services. Design single-bound dichotomous survey questionnaires to study the willingness to pay and the total economic value and examine the validity with the receiver operating character curve. The regression analysis indicates that:The mean value of WTP to the ecosystem services of the urban river and lake is 105.83 Yuan(RMB) per household annually and the estimated value of restoring the ecosystem services of the river and lake in Nanchang city is about 40790 thousand Yuan per year; The value of bid and the level of education are the major factors influencing the residents'willingness, and the probability under the receiver operating character curve is 0.782 which indicates some validity of the present model.By using the technology of RS and GIS, as well as the cost-benefit analysis in Ecological Economics, the thesis assesses the evolving course of water ecosystem services value. The results show that:From 1989 to 2008, the area of urban rivers and lakes changing into other land-use categories is 15087204m2, about 794064m2 annually; And the area of other land-use categories changing into rivers and lakes is 1259114m2, about 66269m2 annually. Overall, the water area has decreased almost 21 percent since 19 years ago, which transformed into farmland, woodland, and construct terra. However, the whole value of water ecosystem services is increasing from 84.1×107 Yuan to 108.81×107 Yuan; Further analysis shows that this is mainly because people are making more and more use of water supplying services.