全国小流域分布式单位线综合分析

基于全国小流域数据集,采用相关性分析和基于最小二乘法的多元回归非线性模型进行了小流域分布式单位线的综合分析,并以全国30个不同地形地貌类型区的中小流域为例开展了应用研究。研究表明:小流域不均匀系数、加权平均坡度反映了小流域汇流非均质分布特性,小流域属性与单位线特征值(洪峰流量、汇流时间和峰现时间)之间存在中度-强度相关关系;单位线洪峰流量、汇流时间和峰现时间最优公式型的均方根误差分别为0.14～0.75 m3/s、3.16～7.21 min和3.15～7.33 min,合格率分别为86%～100%、85%～100%和65%～100%,相关系数分别为0.93～0.99、0.89～0.99和0.83～0.98,构建的单位线特征值综合公式较好地反映了不同地形地貌类型区洪水集中度和汇集时间的差异性。研究可为缺资料地区中小流域暴雨洪水分析计算和山洪早期预报预警提供技术支撑。

Synthesis of national distributed unit hydrographs

On basis of the national small catchment dataset, the synthesis of distributed unit hydrographs is carried out using correlation analysis and multiple regression nonlinear model in 30 small and medium sized catchments with different topography and landforms across China. Results show that:the proposed nonuniform coefficient and the weighted average slope can well represent the heterogeneous distribution of flood concentration in small catchment, and there is a moderate to strong correlation between the small catchment attributes and the characteristic values of distributed unit hydrographs (i.e.,peak flow rate,flood concentration time and peak flow occurrence time); the optimal empirical formulas are derived for the peak flow rate, flood concentration time and peak flow occurrence time, their root mean square errors are 0.14 m³/s~0.75 m³/s, 3.16 min~7.21 min and 3.15 min~7.33 min, respectively, their satisfied ratios are 86%~100%, 85%~100% and 65%~100%, respectively, and their correlation coefficients are 0.93~0.99, 0.89~0.99 and 0.83~0.98, respectively. The derived optimal empirical formulas perform well in reproducing the flood concentration processes in catchments with various topography and landforms. This study is expected to provide technical supports for storm and flood analysis and the early warning and forecasting of flash flood in small and medium sized catchments in ungauged regions.