三门峡水库河床纵剖面的调整

Adjustment of longitudinal bed profile of riverbed in Sanmenxia Reservoir

通过对三门峡水库建库40多年来的实测资料分析,探讨了水库不同运用时期的河床纵剖面特点,对潼关至段河床比降的变化规律进行了研究。结果发现,如果汛期来水量小,沿程冲刷和溯源冲刷能力就小,非汛期回水在潼关附近河段形成的淤积,汛期得不到有效冲刷;如果来水量较丰,沿程冲刷和溯源冲刷能力就大,两种形式的冲刷相互叠加形成全库区的普遍冲刷下降。潼关至段河床比降主要取决于坝前水位条件,与7年移动平均坝前水位之间具有较好的相关关系,其中受最近3年坝前水位条件的影响最大。

The characteristics of longitudinal bed profiles in Sanmenxia Reservoir in different reservoir operation periods are analyzed based on data measured in the past 40 years. The major factors affecting the longitudinal profile in the river reach from Tongguang to Guduo are investigated. It is found that both the streamwise erosion and the headward erosion are too small to remove all the sediment deposited in the vicinity of Tongguang during the non-flood season due to backwater effect, if the runoff in flood season is small. Contrarily, both the streamwise erosion and the headwise erosion will be strong enough to flush and lower the channel bed in the entire reservoir area, if the runoff in flood season is large. The analysis also shows that the channel bed slope in the river reach from Tongguang to Guduo is closely related to the 7 years' moving average pool levels and mainly affected by the levels in the latest 3 years.