山丘区小流域单位线峰值经验公式推求研究

Research on the Derivation of Empirical Formula for the Peak Flow of Unit Hydrograph of Small Watershed in Mountainous Area

基于考虑雨强、流域下垫面异质性的分布式地貌单位线,开展无资料山丘区小流域单位线峰值经验公式推求研究。选取河南省伊河、重庆市龙河、甘肃省泾河、河北省拒马河、云南省牛栏江5个典型流域,采用成因分析结合逐步回归的方法识别影响小流域单位线峰值显著的下垫面因子,进一步构建推求单位线峰值的经验公式。结果表明,一定降雨强度下,流域面积、最长汇流路径长度及最长汇流路径坡降对小流域单位线峰值影响最为显著;由显著性因子构建的单位线峰值经验公式在所选5个典型流域计算效果非常理想,合格率均为90%以上。考虑雨强和流域下垫面异质性的分布式地貌单位线结合所推求的峰值经验公式,具有在无资料山丘区小流域进一步推广应用的潜力,研究成果可为山洪防灾减灾工作提供实际参考。

Based on distributed geomorphologic unit hydrograph which takes rainfall intensity and underlying surface variability into consideration, research is done on the derivation of empirical formula for the calculation of peak flow of unit hydrograph of small watershed in mountainous area. Five watersheds, Yi River in Henan Province, Long River in Chongqing, Jing River in Gansu Province, Juma River in Hebei Province and Niulan River in Yunnan Province are chosen as typical watersheds, and then stepwise regression with casuse analysis is used to identify the significant underlying surface factors toward peak value of distributed geomorphologic unit hydrograph. As a result, the empirical formula calculating peak value is proposed. The results indicate that the catchment area, length and slope of the longest confluence path are significant factors under certain rainfall intensity and the empirical formula which is composed of the significant factors performs well, with high fitting qualification rates (more than 90%) in each typical watershed. Distributed geomorphologic unit hydrograph which takes rainfall intensity and underlying surface variability into consideration, together with the empirical formula proposed, have potentials for further application, and this study provides a practical reference for the work of prevention and reduction of flash flood.