一、前言 1983年7月31日汉江上游发生了一场特大的洪水,安康的洪峰流量高达31000秒立方米。在这场雨洪过程中,对洪峰起决定作用的最大,日流域(安康以上)平均雨量仅为70.9毫米,是常遇降雨;但相应的洪峰流量却是稀遇的,雨、洪关系极不对应。这种情况出现的最重要原因是暴雨中心移动与区域干、支流汇流方向相应,上、下游,干、支 I. Preface An extraordinary flood occurred on the upper reaches of the Han River on July 31, 1983. Ankang’s flood peak flow reached 31,000 cubic meters. In the process of this rainstorm, the largest peak in determining the peak is the average daily rainfall of only 70.9 millimeters in the daily watershed (above Ahn’s-beaten), which is often the case with rainfall; however, the corresponding peak flow is rare, and the relationship between rain and flood Does not correspond. The most important reason for this situation is that the movement of heavy rain center corresponds to the confluence of dry and tributaries in the area, and the upstream, downstream, stem and branch