基于对比观测试验与模拟的城市化下暴雨洪水演变机理分析

城市化下暴雨洪水问题日益突出，定量刻画并揭示其演变规律与驱动机理是当前水文学研究的重点与难点问题。本项目将以我国高度城市化的长三角地区为例，以“城市化下产汇流机制分析—城市化下暴雨洪水演变规律揭示—城市化对暴雨洪水影响程度定量评估”为主线，深入揭示城市化地区暴雨洪水演变的微观机理。首先，基于典型下垫面土壤水原位观测和不同城市化流域对比观测试验，分析不同下垫面对降雨的再分配作用，探讨城市化对产汇流过程的影响；其次，基于长序列降雨径流和高分辨率暴雨洪水观测资料，分别从纵向时间尺度和横向不同城市化流域分析暴雨洪水演变规律，探讨城市化地区暴雨洪水的主要驱动因素；在此基础上，通过不同情景下流域暴雨洪水过程模拟，定量评估城市化对暴雨洪水的影响程度，探讨城市化下暴雨洪水演变机理。研究结果对于深入揭示城市化对暴雨洪水的作用机制有较高参考价值，将为保障城市化地区洪涝安全和促进社会经济可持续发展提供科学依据。

The disasters caused by rainstorm floods are getting more and more serious under the background of urbanization, and quantitatively examining and revealing the evolution and driving mechanism of rainstorm floods are the key and difficult scientific issues in recent hydrological researches. Taking the highly urbanized Yangtze River Delta region as an example, this project follows the main line as “the analysis of the mechanism of runoff generation and routing under the influence of urbanization – the revelation of the evolvement rule of rainstorm floods – the quantitative assessment of the degree of urbanization impact to rainstorm floods”, and will deeply reveal the microcosmic mechanism of the changes in rainstorm floods in the urbanized areas. Firstly, based on the in-situ observation of soil water under typical underlying surface and hydrological comparative experiments in basins with different urbanization level, the reallocation role of different underlying surfaces for rainfall will be analyzed, and the effect of urbanization on the processes of runoff generation and routing will be explored. Secondly, based on long series rainfall-runoff and high-resolution rainstorm floods observation, the evolvement rule of rainstorm floods caused by urbanization will be analyzed from the longitudinal time scale and the horizontal comparison of different basins, and the main driving factors of rainstorm floods in urbanization area would be detected. On this basis, the rainstorm floods simulation under different scenarios will be carried out to quantitatively reveal the extent of urbanization effect on rainstorm floods, and to explore the evolution mechanism of rainstorm floods induced by urbanization. The results are of high theoretical value for understanding the influencing mechanism of urbanization on rainstorm floods, and will provide a scientific basis for ensuring floods safety and promote sustainable development of society and economy in urbanized areas.