Dynamic changes and its factor analysis of urban wetlands in Wuhan, China from 1950s to 2005 year

Urban wetlands play a significant role in the sustainable development. But the effect of human action on urban wetlands has been expanded in greater scope and depth, which may cause the accelerated degeneration of urban wetlands seriously. Based on the historical data of land using maps, topographic maps and TM images of Wuhan from 1930s to 2005, which were through the Man-Machine Interaction in ArcGIS System and ERDAS IMAGINE, and the field data through the fieldwork and questionnaire research in 2009 and 2010, the urban wetland database from 1930s to 2005 in Wuhan had been established. Then, the spatio-temporal evolution of urban wetlands was quantitatively and qualitatively analyzed. Urban wetlands have been degenerating seriously, and the tendency of its degeneration is all but irreversible. The results showed that: (1) the area of natural urban wetlands decreased: lake wetlands decreased by 55% from 1930s to 2005; (2) pollution state of urban wetlands worsened: no lakes reached Grade I, and the remaining 65.4% exceeded Grade V; (3) decline in biodiversity had been becoming worse and worse; (4) the urban wetland landscape fragmentation had augmented a lot. Based on the statistic data of socio-economic factors from 1930s to 2005, we analyzed dynamic changes of urban wetlands, and by making use of the correlation analysis of SPSS, analyzed the direct factors consisting of agriculture-inning, engineering construction, resource utilization and biological invasion, and the basic factors consisting of population explosion, urbanization, industrialization, mass consciousness and public policy.