Impact of Urbanization on Hydrological Processes: A Case Study of Xinji River in Southern China

Urbanization has become a global trend over the past century. Urbanization, causing significant changes on watershed land use/cover (LUC) types, changes the hydrological characteristics of urbanized watersheds. Surface peak flow and runoff coefficient are the most impacted hydrological index. The increased peak flow and higher runoff coefficient requires increased flood mitigation capacities. To better adapt to this change, quantitatively determining the effect of urbanization on the hydrological processes is extremely important for watershed planning and management. This article studied the impact of urbanization on the peak flow and runoff coefficient of Xinji River in southern China, a highly urbanized watershed. The Liuxihe model, a physically based, distributed hydrological model proposed for watershed flood forecasting is employed to simulate the flood processes of Xinji River, and the LUCs at 12 time periods derived from satellite remote sensing imagery are used to estimate the model parameters induced by urbanization. The results show that from 1987 to 2015, in less than 30 years, the urban land area of Xinji River increased from 0.8% to 45.1%, a rapid urbanization. Land use change has significantly changed the flood characteristics of Xinji River. The peak flow in 2015 had an average increase of 67.83 m(3)/s than that in 1987, while the average runoff coefficient increased 0.289.