INFLUENCE OF RADAR RAINFALL HORIZONTAL RESOLUTION ON HYDROLOGICAL SIMULATION - A CASE STUDY OF XITIAOXI WATERSHED
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摘要: 天气雷达估测降雨是径流模拟和洪水预报的重要信息之一。由于雷达网格降雨存在误差,且误差随着网格水平尺度的增大而减小,因此对于径流模拟,高分辨率的雷达降雨数据并不意味着径流模拟的精度更高。采用FSS(Fractions Skill Score)方法和HEC-HMS模型(Hydrologic Engineering Center's Hydrologic Modeling System)分析江苏省西苕溪流域雷达估测降雨水平分辨率对径流模拟的影响。在2010年和2011年夏季两场降雨实例中,雷达估测降雨在不同降雨阈值情况下,FSS达到目标精度值对应的最小有效水平尺度为2~8 km,分别以2、4、6、8 km水平分辨率的雷达估测降雨和雨量站测雨作为HEC-HMS模型输入进行径流模拟,结果表明:基于不同水平分辨率的雷达估测降雨的径流模拟结果与实测径流资料基本吻合,雷达估测降雨2、4、6、8 km水平分辨率的变化对径流模拟效果的影响不明显。Abstract: Weather radar rainfall is one of the important information for runoff simulation and flood forecasting. Because each grid point rainfall value is susceptible to error, and radar rainfall error decreases as the temporal and spatial scales increase, high resolution does not necessarily equate to higher accuracy in applications such as hydrological simulation. In this paper, the Fractions Skill Score (FSS) and HEC-HMS (Hydrologic Engineering Center's Hydrologic Modeling System) are used to analyze the influence of radar rainfall horizontal resolution on hydrological simulation. In the two summer events from 2010 to 2011 in the Xitiaoxi River basin, FSS can achieve the target precision value at minimum effective horizontal scale of approximately 2—8 km with different radar rainfall threshold. Radar rainfall at the horizontal resolution of 2, 4, 6 and 8km is used as input data in the HEC-HMS model. Analysis of the simulation results reveals that the results of runoff simulation based on different horizontal resolution radar rainfall are basically consistent with the measured runoff data, and the influence of radar rainfall horizontal resolution at 2, 4, 6 and 8 km on hydrological simulation is not obvious.
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Key words:
- applied meteorology /
- radar rainfall /
- FSS method /
- runoff /
- horizontal resolution
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表 1 降雨事件1径流模拟相对误差和Nash-Sutcliffe相关系数
误差项 雷达 雨量站 2 km 4 km 6 km 8 km 总径流量相对误差/% -6.8 -14.0 -2.1 -19.3 6.8 洪峰流量/% -2.1 -29.2 -11.1 -9.8 4.5 洪峰现时误差/h -2 -4 -1 -3 0 Nash-Sutcliffe相关系数 0.9 0.78 0.8 0.71 0.93 注:负的洪峰现时误差表示模拟洪峰现时比实测的早。 表 2 降雨事件2径流模拟相对误差和Nash-Sutcliffe相关系数
误差项 雷达 雨量站 2 km 4 km 6 km 8 km 总径流量相对误差/% 9.9 3.9 1.0 0.6 0.2 洪峰流量/% 6.3 1.7 -1.1 -1.5 -4.6 洪峰现时误差/h 3 3 3 3 -1 Nash-Sutcliffe相关系数 0.83 0.85 0.86 0.86 0.94 -
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