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多沙的黄河,造成“善淤、善决、善徙”的特性,引起下游严重淤积。泥沙大量淤积在河槽内,下游河床每年以10厘米左右的速度抬高。1958年至今平均淤高4米左右,郑州以下,黄河都是地上悬河,高出地面10米以上。河道形态恶化,洪水容易上滩,上滩流量已由80年代的6000立方米每秒降低到目前的3000多立方米每秒。河床不断淤积抬高,堤防抗洪标准愈来愈低,为维持堤防的防御能力,不断加高加固,才能保持河道淤积抬高的防洪标准。河床淤高还使水流浅宽,游荡性增加,出现斜河、横河的机遇加大,水流可直冲大堤,中小流量也会出现大险情的不利形势;另外也使凌汛危害加剧。
The Yellow River, with a high degree of sedimentation, caused the characteristic of “good siltation, good solution and good migration”, causing serious siltation in the lower reaches. Sediment deposition in a large number of river channels, the downstream riverbed elevation of about 10 cm per year. Since 1958 the average silt height of about 4 meters below Zhengzhou, the Yellow River are hanging on the river, above the ground 10 meters above. The deteriorating river shape, easy flooding on the beach and upper beach traffic have been reduced from 6,000 cubic meters per second in the 1980s to over 3,000 cubic meters per second today. The siltation of the riverbed is constantly rising and the embankment flood fighting standard is getting lower and lower. In order to maintain the defensive capacity of the embankment and continuously increase and reinforce the embankment, the flood control standard of riverbed siltation can be maintained. The siltation of the river bed also makes the water flow shallow, wandering increased, there oblique river, Yokogawa opportunities to increase, the water can be straightforward embankment, small and medium-sized flow will also appear adverse situation of big danger; In addition also aggravates the flood risk.