Dynamic Analysis Of Wetland And Security Assessment In Zhejiang Jinhua And Quzhou Basin During 1997-2004

Wetland ecosystems provide a variety of resources for human life and production, and serve as the base for human survival and socio-economic development, given their multiple functions like supply, regulation, culture and ecological support functions. It is of significance to investigate the spatiotemporal dynamics of wetlands as well as the contributing factors. So far, most related research focused on natural wetlands, and artificial wetlands (artificial marshes, paddy fields, reservoirs, etc.) were thus received relatively less attention. They are limited to the aspects related to ecological characteristics and landscape patterns of wetlands. In addition, related research is limited to certain scales, such as conservation region, riparian zone, and etc, and little research is carried out at macro-or watershed scale. Under such circumstances, this study, with a case study of Jinqu Basin, applied 3S techniques to characterize wetland dynamics; proposed ecological impact assessment model to assess the ecological conditions of wetlands, using the interpreted results and social-economic statistical data; and analyzed the contributing factors and drivers and finally provided some suggestions for ecological storage of wetlands. The main conclusions are presented as follows:(1) The paddy area decreases rapidly during 1997-2000, and the area of ponds and river increases. Paddy and ponds area increases during 2000 and 2004. The area of paddy increases from 1997 to 2000 with elevation 0 to 50 meters, but decreases in 2004. Paddy area decreases year by year with elevation 50 to 100 meters, and in other elevation region it conforms the law of decreasing first and then increasing. Paddy area with slopes grade 1 increases year by year and the change trends of other slopes grades are 1997>2004>2000. Comparing the different capacity of paddy area change, the trends of grade 2 is 2000<1997<2004, grade 3 is 2000<2004<1997, grade 4 is 2004<1997<2000, and grade 5 is 1997<2000<2004, respectively. Comparing the different soil types area change, the trends of Limestone soils is 2000>2004>1997, the trends of Fluvo-aquic soils is 2004>2000>1997, the trends of Paddy Soil, Red earths, Yellow earths and Skeletol soils is 1997>2004>2000, the trends of Purplish soils is 2004>1997>2000.(2) PSR model based on Catastrophic Theory was structured and the result shows that Catastrophic Theory Modeling was able to reflect wetland ecological regime more correctly, objectively and scientifically. The result of assessment indicates that the overall score in 1997 of all counties and the entire Jinqu Basin was distinctly higher than that in 2004. The rank of Each county appears steady:Jiande and Pan'an got the first place all the time; Jinhua and Longyou kept the best environmental regime of wetland except few counties or cities whose rankings have large alteration, such as Quzhou, Yongkang, Lanxi, Yiwu. We can argue from the figure of change of average score in Jinqu Basin, that the rate of decent of environmental wetland regime in cities was universally higher than those in counties, that east part was higher than west, and that counties or cities with fully-developed industrialization were higher except Jinhua. (3) Natural factors, elevation and aspect in particular, were the main indirect drivers, given that they determine the rate and intensity of land use change. Population growth was one of the main direct drivers. The total output of industry and agriculture were also significantly associated with the changes of wetlands. Finally, policy was also important factor. Generally, for industrial, particularly high-pollution enterprises concentrated, counties, the annual industrial output value increased rapidly, and the ecological quality of wetlands declined rapidly, despite of environmental protection activates. For counties with better ecological attributes but lower social-economic development level, the ecological quality of wetlands declined rapidly, after the proposal of industrial revitalization and agricultural industrialization policies. For more developed counties, which pay more attention to the competitive power as well as government image and citizen's life quality, the rate of decline in ecological quality would slow down.