1960-2017年北洛河下游冲淤变化特征及其成因分析

基于1960-2010年北洛河状头站实测水沙及1960-2017年北洛河下游淤积断面测验资料,采用原型观测的方法,统计分析了北洛河下游泥沙淤积量、典型横断面及河道纵比降变化,采用Mann-Kendall趋势检验法对状头站的径流量及输沙量变化趋势进行显著性检验,探讨了北洛河下游冲淤变化特点及其成因。结果表明:1960-2017年洛淤1~洛淤21河段累计淤积泥沙2.870×10^8m^3,期间滩面淤高、河道纵比降自1965年的1.618■持续增大至2017年的1.941■,三门峡水库蓄水初期及高含沙洪水是河道淤积的主要时期,其中1994年高含沙大洪水河段泥沙淤积量占累计淤积量31.3%;水沙条件及潼关高程是影响北洛河下游冲淤变化的主要原因,2000年以来,北洛河下游径流量、输沙量显著减小,2000-2010年状头站多年平均汛期输沙量比1960-2010年减少67.5%,漫滩大洪水少有发生,加之在三门峡水库原型试验按非汛期最高水位不超过318.0m运用期间潼关高程缓慢下降,北洛河下游冲淤态势总体保持稳定。

The variation characteristics and cause of scouring and silting in the lower Beiluo River from 1960 to 2017

Based on the observation data of flow and sediment of Zhuangtou Station of Beiluo River in the period of 1960-2010 and test results of the cross section of sedimentation in the lower Beiluo River in the period of 1960-2017,the variation characteristics and cause of scouring and silting in the lower Beiluo River were studied.Changes of sedimentation amount,typical cross section and river bed slope were analyzed with prototype observation method.And then,the trend of runoff volume and sediment transport amount of Zhuangtou Station was tested with Mann-Kendall method.The results showed that the cumulative sedimentation amount of Luoyu 1-Luoyu 21 reach was 2.870×10^8 m^3 in the period of 1960-2017,during which the floodplain height and river slope increased from 1.618■in 1965 to 1.941■in 2017.The initial storage period of Sanmenxia Reservoir and hyper-concentrated sand flood period were the major sedimentation periods of the river.During flood period in 1994,the sedimentation of Luoyu 1-Luoyu 21 reach accounted for 31.3%of the total cumulative sedimentation.The flow and sediment condition and Tongguan elevation are the main reasons of variation of scouring and silting in lower Beiluo River.The runoff and sediment transport amount of lower Beiluo River decreased significantly since 2000.The average sediment transport amount from 2000 to 2010 of Zhuangtou Stations decreased by 67.5%,compared with that from 1960 to 2010.And overflowing flood was a rare occurrence.With the implementation of maximum water level of 318.0 m since the prototype experiments started in Sanmenxia Reservoir,Tongguan elevation gradually droped,generally,the scouring and silting situation maintained stable.