Development and challenges of urban hydrology in a changing environment：I：Hydrological response to urbanization

The change in the natural hydrologic processes impacted by global climate change and rapid urban expansion is a hotspot issue in the field of urban hydrology. To understand the evolvement rules of urban water cycle, we discuss the development in urban hydrology, and reveal the response mechanism of hydrological processes in urban environment. Then, we summarize the advances in the effect of urbanization on hydrological regime, including hydrological cycle and water resources management, water quality and environment, and water ecosystem. There have been significant recent advances in the measurement and modeling the hydrological responses to urban expansion, with technologies such as experiments and hydrological models. Despite the advances, many new challenges in urban hydrology remain, especially in a changing environment, which impose a requirement to ensure that sustainable urban development are adaptable and resilient to changes. Further researches into the spatio-temporal dynamics response of urban rainfall, causes of urban extreme storm, quantification of the effects of urbanization on hydrological response and water ecosystem, and urban water management are required to pay more attention to. Urban hydrology will play a critical role in addressing these challenges, to support scientific foundations for establishing eco-city and ensuring water safety for cities.