So this article analyses deeply in the method of ensur ' my designing food rolume which is an important element to affect the " designimy height of bridge " it brings forward an " arverage optiminmy suiting line " method which is a bondage discommode series at the same time it puts forward a ensurmy principle for rough coefficient " and " fallimy flood proportion which are both suitable to heilongjiang province at last this article introduces the " three - days rainimy rolume " method 本文立足于黑龙江省各种河流的洪水特点，结合以往工程实际，对影响跨河桥梁设计高度的主要因素? ?设计洪水流量及其相应洪水位的确定方法加以详细分析。提出有约束不连序系列的加权优化适线法及适合于黑龙江省的河流粗糙系数和洪水比降的确定原则，并介绍了三日降雨量法。
