一、形成洪水灾害的原因是多种多样的有暴雨形成的洪水(雨洪);有融雪造成的洪水(春汛);还有降雨兼融雪造成的洪水(俗称桃花汛),这种情况的次雨量的径流系数较大。我国北方,特别是高寒地区,以上三种成因的洪水经常发生。水利工程设计中如何确定某一流量的相应频率是个值得探讨的问题。当前频率计算中对不同成因洪水大体有 First, the flood disaster is caused by a variety of floods (rainstorms) caused by heavy rains; floods caused by snowmelt (spring floods); and floods caused by precipitation and snow melt (commonly known as peach blossom floods). In this case, The runoff coefficient of rainfall is larger. In the northern part of our country, especially in the alpine region, floods of the above three causes often occur. How to determine the corresponding frequency of a certain flow in water conservancy project design is worth discussing. The current frequency calculation of floods of different causes generally