Estimating the Impacts of Urbanization in the Next 100 years on Spatial Hydrological Response

Figuring out the impacts of future urbanization on hydrological response is significant in a rapidly changing environment. As an important urbanization element, the various impacts of land use/land cover change have been studied a lot with the methods of combining different land use scenarios and hydrological models. However, it needs to be improved because of only simplified land use scenarios being considered, which cannot reflect the real urbanization process of the future. Taking into account the roles of social and economic development, in this paper, a hybrid FLUS-SWAT method is proposed for the first time for accurately evaluating the hydrological responses to urbanization. First, instead of subjective assumption, future land use patterns are predicted by developing improved cellular automata model on driving forces involving regional population, gross domestic product, location, transportation network, etc. Then, spatial hydrological responses were individually analyzed by coupling projected future land use scenarios and distributed hydrological model. The results clearly forecasted a burst of urban expansion in future 100 years in Zhexi river basin, China. Loss of forest and agriculture land will lead to a 64.86% increase in surface runoff and 9.05% decrease in groundwater flow. This study is significant for ecological environment planning because it provides a direct understanding of future urbanization level as well as its impacts on hydrological processes.