【作者】 彭俊；

【导师】 陈沈良；

【作者基本信息】 华东师范大学 ， 自然地理学， 2011， 博士

【摘要】 黄河是我国第二大河流,以高含沙量闻名于世。过去治理黄河的首要问题是治理黄河泥沙,尤其是中游地区的来沙。历史上黄河的高含沙量导致下游河道淤积并发生漫滩形成泛滥平原,给人民生活带来沉重的灾难。然而,黄河的高含沙量形成了宽广的三角洲,为社会经济的发展提供了可供利用的土地资源。本文运用统计学方法,小波分析方法,回归分析方法以及Surfer和Mapinfo等技术手段,系统分析了1950-2009年黄河水沙的变化过程,以及水沙变化对下游河道和三角洲的影响,同时对黄河三角洲沉积环境演变进行了初步探讨,结果表明：黄河流域水沙产自中上游,其中径流量主要来源于上游,输沙量主要来源于中游,下游不产水不产沙。1950-2009年黄河流域各水文站径流量和输沙量均表现出逐渐减少的变化趋势,这是气候变化和人类活动共同影响的结果。流域输沙量减少最主要的影响因素是水土保持措施,其次是水库拦沙,然后为降雨量减少。黄河入海水沙具有显著的年(0.5-1.0a)、年际(3.0-6.5a)和年代际(10.1-14.2a)3个不同时间尺度的周期变化,而且入海输沙量的周期变化主要受入海径流量周期变化的控制。20世纪70年代以来,入海水沙的不同时间尺度的周期变化表现均不明显,时间尺度越小,周期变化显著性越低。1950年以来,黄河下游河道经历了淤积-冲刷不断交替的变化过程,水沙条件(花园口站含沙量)是这种变化的主要控制因素。当进入下游河道的含沙量小于18.6kg/m3时,河道表现为冲刷,大于18.6kg/m3时,河道表现为淤积。艾山以下河道的冲淤变化过程除受水沙条件控制外,还受到入海流路变迁的影响。流路变迁初期形成新河口,河道发生溯源冲刷；流路变迁中后期河口延伸,河道发生溯源淤积。不同流路时期,当黄河入海总水沙量比在25.34-26.05kg/m3时,河口附近岸线延伸,三角洲面积增加。但1999年小浪底水库下闸蓄水以后,2000-2007年黄河入海总水沙量比仅为10.90kg/m3,河口三角洲表现为侵蚀,加上废弃河口的岸段侵蚀,整个黄河三角洲已由淤积转变为侵蚀。黄河三角洲YDZ1孔沉积物类型主要为砂、粉砂质砂、砂质粉砂、粉砂和粘土质粉砂。以假单畴(PSD)-多畴(MD)晶粒为主的亚铁磁性矿物主导了YDZ1孔沉积物的磁性特征。根据YDZ1孔沉积物粒度参数和磁学参数的变化特征,结合AMS14C测年,推断黄河三角洲沉积相序自上而下大致经历了泛滥平原相→河流相→三角洲前缘相→浅海相→潮坪相→河流相,沉积动力环境表现为强(陆相)→弱(海相)→强(陆相)的变化过程。更多还原

【Abstract】 The Yellow River is the second river of China, with world-famous of its high sediment-laden water. In the past, to harness the Yellow River, the first issue should be managing the river sediment, especially the river sediment from the middle reaches should be decreased as much as possible. In history, the sediment-laden water of the Yellow River has resulted in serious siltation in the lower reaches and the floodplain, which bringed heavy tragedy to people’s life. However, the sediment-laden water has developed the large Yellow River Delta, which can provide available land resource for the development of society and economy. By means of statistics, wavelet analysis, regression analysis and softwares of Surfer and Mapinfo, this paper analyzes the variation processes of water discharge and sediment load in the Yellow River from 1950 to 2009, expatiates the effect of variation of water discharge and sediment load to the lower reaches and the river delta, and discusses the evolution of sedimentary environment of the Yellow River Delta. The results are shown as follows:Water and sediment in the Yellow River Basin yield from the upper-middle reaches, but have different sources. The water discharge is derived mainly from the upper reaches and the sediment load is derived mainly form the middle reaches. The gradual decreases of water discharge and sediment load in hydrological stations of the Yellow River Basin from 1950 to 2009 are strongly influenced by climatic change and human activities. The main factor to river sediment decrease is water-soil conservation practices in the middle reaches, the second contribution is attributed to sediment trapping by reservoirs, and the following contribution is precipitation decrease. Water discharge and sediment load transport into the sea by the Yellow River have three distinct time-scale period variations of annual vatiation (0.5-1.0a), inter-annual variation (3.0-6.5a) and inter-decadal variation (10.1-14.2a), and the period variation of sediment load is mainly controlled by the period variation of water discharge. Since 1970s, the three distinct time-scale period variations are unconspicuous, and with the shorter of time-scale, the lower conspicuousness of period variation. Since 1950, the lower Yellow River has experienced alternate phases of siltation and scouring due to changes of water discharge and sediment load at Huayuankou hydrological station. When the suspended sediment concentration at Huayuankou is less than 18.6kg/m3, the lower reaches tend to experience scouring. Otherwise siltation is the dominant process. Except controlled by water discharge and sediment load, siltation and scouring downwards from Aishan reaches have been affected by tranfers of river course to the sea. The reaches has experienced upriver scouring through forming new river mouth in early days of river course transfer and it has exhibited upriver siltation as extension of river mouth in mid-late time of transfer. Over most of the data period, when the ratio of total water discharge and sediment load into the sea (SSCT) locates in 25.34-26.05kg/m3 in different periods, the coastline near river mouth has extended and the delta area has increased through progradation. However, since the operation of Xiaolangdi reservoir in 1999, the SSCT as recorded at Lijin from 2000 to 2007 is only 10.90kg/m3. The value clearly indicates the estuarine delta has been starved of sediment. The coasts near abandoned river mouths have been eroding since the river sediment supply was cut off. Hence, the whole Yellow River delta has displayed erosion from siltation.The sediment types of Core YDZ1 in the Yellow River delta are sand, silty sand, sandy silt, silt and clayey silt. The ferrimagnetic mineral of pseudo-single domain (PSD) and multi-domain (MD) in size dominates the magnetic properties of the samples from Core YDZ1. According to variation characteristics of granularity parameters and magnetics parameters of sediment from Core YDZ1, and combining with dating by AMS14C, we deduce that the sedimentary facies from top to bottom in the Yellow River Delta has experienced floodplain facies, river facies, delta-front facies, neritic facies, tidal flat facies and river facies in sequence, and the sedimentary dynamical environment had exhibited variation process of relative strong (terrestrial facies), relative weak (marine facies) and relative strong (terrestrial facies).更多还原