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龙羊峡、刘家峡两库联合运用后黄河中游干流汛期水沙条件发生了很大变化。具体表现为：①伏汛期河口镇、龙门、潼关三站水量多年平均比１９６８年前减少５０％左右，沙量减少约６０％，但相应水沙量占全年比例变化不大；秋汛期水量减少５０％以上，沙量减少６５％～８０％，相应水沙量占全年比例明显降低，同时年际间水沙量变幅减小。②水流过程的变化，伏汛期主要表现在２０００ｍ３／ｓ以上中、大流量级历时、水量、沙量的明显减少和１０００ｍ３／ｓ以下枯水流量的增加；秋汛期１０００ｍ３／ｓ以下小流量历时出现几率大大增加，水沙量也相应增多；而１０００ｍ３／ｓ以上中、大流量明显减少，９月下旬和１０月份水沙量与非汛期特征十分接近。
After the combination of Longyangxia and Liujiaxia two reservoirs, the water and sediment conditions of the main stream in the middle reaches of the Yellow River during flood season have undergone great changes. The specific performance is as follows: (1) During the flood season, the average annual water consumption of Hekou Town, Longmen and Tongguan stations decreased by about 50% compared with that before 1968, and the sediment volume decreased by 60%, but the corresponding proportion of water and sediment did not change much in the whole year; Reduce the amount of sediment by 50% or more, decrease the sediment yield by 65% ~ 80%, and the proportion of sediment and sediment in the whole year decreased obviously. (2) The change of water flow during the flood season is mainly manifested in the medium and large flow rates of over 2000m3 / s, the significant decrease of water flow and sediment volume and the increase of dry flow below 1000m3 / s; the small flow below 1000m3 / s appeares in autumn flood season The probability of water and sediment increases greatly, and the amount of sediment and sediment also increases correspondingly. However, the large and medium flow rates of more than 1000m3 / s decrease obviously, and the characteristics of sediment yield and non-flood season in late September and October are very close.