一个新的高分辨率洪涝动力数值监测预报系统

A high-resolution flood forecasting and monitoring system for China using satellite remote sensing data

基于简单的分布式水文模型CREST和多种卫星遥感资料及站点观测资料等，建立了一个高分辨率的动力数值洪涝灾害预报系统．该系统包含数据输入、水文模型、模式输出以及结果验证4部分．数据输入使用了高分辨率卫星遥感DEM等地表下垫面数据作为边界条件，使用时空分辨率和精度都较好的CMORPH卫星遥感降水资料作为驱动数据，驱动分布式水文模型CREST实时运行，以监测和预报中国地区尤其是无站点观测或者站点较少地区的洪涝灾害．对2008—2011年的水文基本变量后报结果结合不同流域水文站点的水文过程线分析验证表明，水平空间分辨率1km的系统能够较好地后报中国地区的基本水文过程，能够较好地后报如实际蒸散发、土壤湿度、地表径流等基本水文变量；系统能够较好地模拟和后报河道径流量涨落过程；能够较好地后报洪峰及其对应的流量．同时，经过几次洪涝灾害事件的分析验证，表明系统能较好地监测、预报洪涝发生的时间及其影响的范围，从而可以为防灾减灾提供参考依据．

Flood disasters occur frequently in China, resulting in property damage and fatalities. To reduce these risks, a high-resolution flood forecasting and monitoring system was developed based on a simple, distributed hydrological model： CREST. There are mainly four parts in this flood forecasting system, which are the data pre-processing and input module, the distributed hydrological model, the results output and post-processing module, as well as the results verification module. The data inputted in this system are high-resolution CMORPH satellite remote sensing precipitation and surface condition data, including ASTER DEM, HWSD soil types and MODIS vegetation and land cover types, or so. Those data were interpolated to 1 km spatial resolution and then used to drive the hydrological model to run. The CREST model was developed to provide rapid online prediction of large area which may be continental scale or even global scale, while it is also applicable at small scales, such as small basins. It can simulate the spatiotemporal variation of water and energy fluxes as long as storages on a regular grid with the grid cell resolution being user-defined, which ranges from meters to kilometers. The results outputted from the forecasting system are hydrological variables like soil moisture, potential and actual evapotranspiration, surface and river runoffs, etc. Results were then applied to GIS system and then translated into flood disaster warning information in the data output and post-processing module of the forecasting system. Both hydrological variables and flood disaster warning information will be tested and verified in the results verification module. With the 1 km horizontal spatial resolution, the forecasting system successfully simulated basic hydrological variables and processes such as actual evapotranspiration, soil moisture, and surface runoff according to the analysis and comparison with observation data. System hindcasted flood disaster information of several flood events were carefully analyzed. The results showed that the hydrographs of several stations hindcasted by the forecasting system demonstrated that the forecasting system can approximately hindcast river runoffs and streamflows. The performance of the forecasting system was tested by analyzing several real cases of flooding in different places in China, and results indicated that the system hindcasted flood information, including flood timing and spatial extent, were useful for disaster preventions and mitigations.