西江四滩河段近10年河床变形与成因分析*

基于2004—2014年西江四滩河段10年实测地形资料，采用Kring插值方法及数理统计的方法，分析该河段近10年的演变，阐明其冲淤变化特征；分析上游来水沙变化和航道整治工程对河道演变影响。研究表明：2004—2014年，四滩河段河床整体处于冲刷下切态势，2007—2013年是冲刷剧烈期；分析认为，导致2004—2014年河床总体下切的主要原因是建库蓄水拦砂为主因的上游年平均含沙量和年输沙量持续大幅度的减少；长洲枢纽2007年起拦砂泄清及航道整治工程是研究河段整治线范围内河槽2007—2013年冲刷剧烈的主要原因；河床下切导致四滩河段最低通航保证流量下水位下降明显，但航道水深有所增加。

Morphological evolution and causes of Sitan reach of Xijiang river in recent decade

Based on topographies from 2004 to 2014 and using the Kring interpolation method and mathematical statistics method,we analyze the morphological evolution of Sitan reach and illustrate the scouring-erosion variation characteristics of channel. We also analyze the influence of the discharge and sediment variation and channel regulation upstream on the morphological evolution. The results show that the overall Sitan reach is in the state of erosion from 2004 to 2014,during which the scouring is severel from 2007 to 2013. The analysis shows that the main reason for the undercutting of riverbed from 2004 to 2014 is the sharp decrease in sediment discharge from upstream due to the construction of more and more dams. The sand blocking effect by Changzhou Dam since 2007 and the channel regulation project from 2008 to 2010 are the main reasons for the sharp erosion during 2007 and 2013. The river bed undercutting leads to the lower water level but will not affect the navigation depth.