Exploring The Relationship Between Rapid Urbanization And Wetland Change

Wetlands are important urban natural assets, and play a great role for urban sustainable development. China has experienced rapid and massive urbanization since its economic reform initiated in 1978. Land resources have become the most valuable resources in cities. Wetlands often have become a priority to be occupied or transformed to other land types. Urbanization has become one of the main causes that lead to the loss of wetlands. However, few studies have assessed the relationship between rapid urbanization.Our study chose Yangtze River Delta Agglomeration as a case study. Four indicators were chosen to evaluate the level of urbanization. The wetland data used in this study were collected from literatures. The stress of urbanization on wetlands can be understood from the ratios between urbanization measures and wetland changes. In addition, the wetland data of Shanghai from 2005 to 2013 were obtained by remote sensing interpretation and classification. Object-oriented segmentation was in combination with decision tree classification using Landsat remote sensing data for the wetland remote sensing interpretation.The study results showed that:Constructed wetlands in Shanghai are much more than natural wetlands. The stress of urbanization led to a large loss of constructed wetlands in Shanghai. And the loss of constructed wetlands dominated the loss of total wetlands in Shanghai. Dued to the loss of constructed wetlands, the wetlands of Hangzhou urban district had been decreasing from 1991 to 2005. In Yancheng, the natural wetlands had been decreasing, and the constructed wetlands had been increasing from 1990 to 2005. The lower the level of urbanization, the higher the demand of urbanization for wetlands. The faster the speed of urbanization, the greater the wetlands change. The higher the level of urbanization, the smaller the urbanization impact on the changes of wetlands. The total natural wetlands of the Yangtze River Delta has been increasing. Urbanization led to the loss of constructed wetlands in Shanghai and Jiangsu. And the constructed wetlands of Jiangsu decreased the fastest.