小流域截洪沟洪峰流量计算方法研究与比较

Study and comparison of calculation methods for flood peak discharge of cut-off ditch in small watershed

截洪沟洪峰流量是截洪沟设计的重要参数。通过工程实例分析比较三种截洪沟洪峰流量计算方法,研究了降雨历时、山洪容重和重现期对三种方法洪峰流量的影响,并分析了各方法主要影响因素的显著程度。结果表明,对于工程实例,方法1(水土保持工程设计规范)和方法3(室外排水设计规范)的结果较接近,更偏安全。洪峰流量随降雨历时的增大逐渐减小,两者呈幂函数关系;洪峰流量随山洪容重的增大而增大,两者基本呈指数函数关系;洪峰流量随重现期的增大基本呈对数增长趋势。方法1和方法3各因素的影响程度从大到小排序为汇流面积>降雨历时>径流系数>重现期;方法2(开发建设项目水土保持技术规范)各因素的影响程度从大到小排序为汇流面积>径流系数>重现期>高含沙山洪容重。

The flood peak discharge of a cut-off ditch is an important parameter in cut-off ditch design.In this paper,we compared three calculation methods for flood peak discharge of cut-off ditches based on a project case.We studied the influence of rainfall duration,unit weight of torrential flood,and recurrence interval on flood peak discharge,and analyzed the significance degree of the influence factors.It was found that Method 1（Code for design of soil and water conservation projects）and Method 3（Code for design of outdoor drainage projects）had similar results for the project case and both leaned towards safety.The flood peak discharge would gradually decrease with the increase of rainfall duration,with a power function relation between them.The peak discharge would increase with the increase of unit weight of torrential flood,with an exponential function relation between them.The peak discharge showed a trend of logarithmic growth with the increase of recurrence interval.Catchment area had the largest influence on flood peak discharge for Methods 1 and 3,followed by rainfall duration and runoff coefficient,while the influence of recurrence interval on flood peak discharge was the smallest.Catchment area had the largest influence on flood peak discharge for Method 2（Technical code on soil and water conservation of development and construction projects）,followed by runoff coefficient and recurrence interval,while the influence of unit weight of torrential flood on flood peak discharge was the smallest for Method 2.