本文主要研究陕西省黄河中游地区黄河、渭河、泾河、洛河四条河流的突发性洪水及相遇问题。暴雨是该地区洪水的重要成因．根据近二千年的历史资料分析，提出该地区的洪水具有周期性；四条河流相遇的概率很小、多形成特大洪水．两河相遇是较常发生的事件，多形成中等以下洪水．三门峡水库的淤积使该地区洪水灾害加剧． This paper mainly studies the sudden flood and encounter of the four rivers of the Yellow River, Weihe River, Jinghe River and Luohe River in the middle reaches of the Yellow River in Shaanxi Province. Rainstorms are an important cause of floods in the area. According to the analysis of historical data in the past two thousand years, it is suggested that the flooding in this area is cyclical. The probability of meeting the four rivers is very small and the extra large floods are formed. The encounter between the two rivers is a more frequent event, with more floods below average level. The siltation of the Sanmenxia Reservoir has exacerbated flooding in the area.