三峡水库库区香溪河河口泥沙淤积特性研究

Sedimentation in Xiangxi River estuary since impoundment of Three Gorges Reservoir

三峡水库库区分布有大小66条支流,水库蓄水后大部分支流河口段淤积明显,常年回水区内部分支流口门形成类似拦门沙的淤积体,可能对水库库容及支流航运造成影响。本文以香溪河河口段为例,分析其泥沙淤积特性及成因。结果表明,2006—2011年香溪河河口段约6.6 km范围内淤积泥沙241万m3,2002—2015年河口段深泓平均抬高7 m以上,口门附近断面最大抬高约12 m,淤积幅度大于干流河段。香溪河河口段淤积的泥沙以干流倒灌为主,随着干支流来沙量减少,其河口泥沙淤积将趋缓。

There are approximately 66 tributaries in the Three Gorges Reservoir（TGR） area, and obvious sediment deposition has been observed in most of the tributary estuaries since the impoundment of TGR. Sedimentation leads to formation of entrance bars at the estuaries, bringing a possible adverse effect to the storage capacity of TGR and the navigation in the tributaries. This paper analyzes the sedimentation in river mouth regions and its main causes, focusing on the case of the Xiangxi River tributary. The results show that in the period of 2006 to 2011, the silted sediment in a 6.6 km long reach of this tributary mouth amounted to a volume of 241′104 m^3, revealing a sedimentation rate larger than that of the Yangtze mainstream nearby. And from the initial TGR impoundment in 2003 to 2015, the thalweg was significantly elevated by 7 m on average over this reach and 12 m at maximum at the mouth. Most of the sediment silted in the Xiangxi mouth came from the section of Yangtze mainstream affected by the TGR backwater. The sedimentation rate will alleviate as the sediment from the upper Yangtze or Xiangxi shows a decreasing trend.