The Pearl River Delta Area is China’s biggest economic zone, which has observed the rapidest urbanization in China in the past 3 decades. In this study, the urbanization processes of Guangzhou City, the hub of South China’s politics, economy and culture, is studied first by using satellite remote sensing imageries. The Landsat satellite imageries is used to estimate the Land use/cover change from 1987 to 2015 at a three year interval by employing the SVM algorithm. Results shows that the Guangzhou City’s LUCC is significant, the unique change is the high urbanization rates among the creeks draining to the city which pose great threat to the city’s flood security.
Based on the above results, the impact of LUCC on flood is studied, and three creeks draining to the city are selected as the study cases. As the creeks in the Pearl River Delta Area only have precipitation observation, no river discharge measures, so the model that could determines model parameters physically from the terrain properties is needed for this study. The Liuxihe Model, a physically based, distributed watershed hydrological model proposed for watershed flood forecasting is employed to simulate the hydrological processes. Liuxihe Model derives model parameters from the terrain properties physically, including the DEM, soil maps and Land use/cover maps, so it is the ideal hydrological model for this study. The Liuxihe Model are set up in the three creeks, and a few flood events with precipitation observations in recent years are simulated, and the results are reasonable good.
Based on the simulation results, the hydrological changes have been analyzed. From the simulated results, it could be found that the hydrological changes is significant, but with different precipitation patterns, the changes are different, and even for different creeks, the changes are also different. Finally the reasons for hydrological changes are studied and the adaptation policies and actions are proposed to mitigate the negative impact of urbanization on flooding.