Wetland Landscapes Evolution In Jiulong River Estuary Under Urbanization Background

The research on wetlands under the urbanization has an importantly practical significance. The intensifying urbanization results in the regional wetland area decreased and the ecological functions degraded severely. Jiulong River Estuary, located in axis of intergration development of Xiamen and Zhangzhou city, inevitably destroys or occupies a portion of the coastal wetlands along with the rapid urbanization of Xiamen and Zhangzhou.This paper selects Jiulong River Estuary as the study area, using decision tree classification to extract wetland resources and SLEUTH model to simulate the dynamic changes of the wetland in 20 years based on multi-temporal remote sensing images. The main contents include:First, extraction of the coastal wetlands resources in Jiulong River Estuary area. Combined with the multi-temporal remote sensing data、DEM and the field survey data, the wetlands have been effectively extracted from the three periods of remote sensing images in 1988,1998 and 2009 by means of knowledge-based decision tree classification method, with the total accuracy of 86.5%,88.4%　and 90.7%　respectively which is in line with the research required accuracy.Second, dynamics monitoring technology research on Jiulong River Estuary wetland landscape. Selecting proper indicators to analyse the landscape pattern of the wetland resources in the Jiulong River Estuary on the level of land and class. The results show that: the Jiulong River Estuary wetland area had an obvious downtrend in the past 20 years with the total area decreased from 34,784.7 ha in 1988 to 20,775.6 ha in 2009. The declining natural wetlands results from the transformation into artificial wetlands and urban construction land. Also, the wetland landscape pattern fragmentation intensified from 1.42 to 1.38 between 1988 and 2009.Third, forecast of the dynamic changes of wetlands on Jiulong River Estuary. Using the SLEUTH model to simulate the urban expansion in Jiulong River Estuary area and forecast the effects of urban expansion on wetland distribution. The simulation results show that, A significant reduction in the wetland area is found in the scenario of maintaining the status quo (MSQ), and more serious degree of fragmentation is detected than that of the scenario of Moderate Environmental Protection (MEP) and Planning Scenario (PS);MEP shows the better result in protecting natural wetlands; PS is the best in controlling the expansion of urban and protection of wetland.Fourth, Impacts of urbanization process on landscape pattern of wetland. Combined with population data、socio-economic data、retrival of land surface temperature、analysis of water colour variation and result of the remote sensing images interpetation to reflect the impact of urbanization on wetlands.The result shows:Urbanzation occupied 6737ha wetlands which was 70.05%　of the overall new increased urban land in twenty years it is urbanization which lead to wetland area reduction、landscape fragmentation, and threat to wetland’s internal living environment.