1997年黄河潼关河段清淤及洪水冲刷效果分析

Analysis of Effects of Sedimentation Clearance and Scouring by Flood in Tongguan Reach of the Yellow River in 1997

1997年汛期黄河潼关站枯水少沙，仅发生一次流量大于3000m3/s的洪水，汛期水量55．53亿m3，较多年平均值偏枯69．3％，是1929年以来水文记载的最小值。洪水前，在潼关以下宽浅河段进行清淤疏浚，采用射流冲沙的方法，以冲为主，冲沙与扰流相结合进行作业，疏浚主河道中的浅滩，封堵串流汊道。清淤后，河势趋于规顺，浅滩段比降增大，水流相对集中，河道形态发生有利变化，增大了河道泄洪输沙能力。7月29日至8月6日洪水期，潼关河床发生强烈冲刷，潼关高程下降1．80m。经峰后河床回淤，汛末潼关高程328．02m，比汛前下降0．22m。

With only once of flood of discharge over 3000 m3/s and water amount of 5. 553 billion m3 in flood season that is less than 69. 3 % of long term average, Tongguan station was of low water and less sediment load in flood season of 1997, which is the minimum in record since 1929. Before flood, sedimentation clearance was carried out in the wide and shallow channel in the reach of lower Tongguan with jet flow method and the working way of mainly jet and combination of jet with disturbance applied for sedimentation scouring in order to clear shallow beach in main channel and clog branch channels. After clearance, the river situation was getting regulated and smooth with slope ratio increased in shallow beach, water flow relatively concentrated, channel configuration changed favorablly, and flood transport and sediment carry capacity enhanced. Severe erosion of Tongguan river bed occurred in the flood process from July 29 to August 6, 1997 which resulted in decrease of Tongguan elevation by 1.8 m, and even sedimentation after flood peak Tongguan elevation was 328.02 m at the end of flood season, lowed by 0.22 m compared to that before the season.