近三十年黄河上游冲积河段的河道平面形态变化分析

黄河上游冲积河段的加速淤积已经严重威胁到当地人民的生产生活。为黄河上游冲积河段减淤措施的制定、消除洪灾隐患,文中基于遥感影像和水文资料,结合地质地貌资料,将冲积河段划分为四段,并根据河道的平面特征,将它们归入不同的河型。对比了1978、1990、2002和2010年四期近三十年宁蒙河段河道的平面变化,发现河道总体上表现出萎缩趋势,但在不同河型上变化过程表现不同,具有一定的复杂性。交错复合型和近顺直型河道主流线长度变化较小,游荡型先减小后增大,弯曲型逐渐增大;从河道平均宽度来看,近顺直型和弯曲型河段都是先加宽后束窄,而游荡型的变化却与前两者相反,呈现出先变窄后加宽,仅交错复合型河段逐渐变窄;四个河段河心洲数量变化呈现出两种情形:略微增加和先增加后减少。这些变化与近几十年上游水库的拦水拦沙是息息相关的。

Planar changes of upper alluvial reaches of the Yellow River in recent thirty years

Based on the data of remote-sensing images,geomorphologic and geologic maps and hydrological data,the Ningxia-Inner Mongolia reaches is divided into four sections.According to planar characteristics,four sections are corresponding to compound of wandering river pattern and branching river,nearly straight river,braided river and meandering river.Comparison of river channel planform from 1978 to 2010 showed that change of river channel width and mainstream length were not monotone increasing or decreasing.As for river mainstream,the mainstream length of branching and nearly straight river had a little change,wandering river reach was decreased in earlier stage and then gradually increased,meandering channel was increased gradually.With respect to river average width,nearly straight river and sinuosity river were firstly widening and then narrowing,process of wandering river width was opposite,only branching river was narrowing gradually.Central shoal quantity changes of different river channel pattern could be divided into two types: one had a little change including Shizuishan-Bayangaole and Sanhuhekou-Toudaoguai;the other one was increasing firstly and then decreasing including Qingtongxia-Shizuishan and Bayangaole-Sanhuhekou.These changes was closely related to reservoir controls in the upstream of Yellow River.