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1.
近50年黄河乌兰布和沙漠段辫状河道演变 总被引：4，自引：3，他引：1
依据水沙资料和断面资料,对黄河乌兰布和沙漠段辫状河道形态近50年演变特征及趋势进行探讨分析。结果表明：在大流量条件下（1966-1993年）,河流横向侵蚀、搬运堆积过程强烈,风沙入黄（河）量大,河道横向摆动频繁,辫状河道发育强烈。当黄河流量减小时（1993-2013年）,河流横向摆动能力减弱,黄河主河槽远离左岸乌兰布和沙漠沙丘,河流输沙能力减弱,汊道泥沙淤积导致心滩边滩相连,河流分汊数量明显减少,辫状河道萎缩,黄河乌兰布和沙漠段辫状河型有向弯曲型河道转变的趋势。 相似文献
2.
黄河流域河型转化现象初探 总被引：9，自引：0，他引：9
黄河以其高含沙水流以及下游河道的高沉积速率而著称于世。迄今的研究, 主要针对黄河中下游流域的 侵蚀、水文泥沙和河床演变方面的研究, 而对黄河流域主支流发生河型转化的现象关注不够。在黄河的不同河段, 河型的变化频繁, 类型多样, 现象复杂, 是研究者不可回避的科学问题。本文选取黄河上游第一弯的玛曲河段、黄河 上游末段托克托附近河段及黄河下游高村上下河段来研究河型转化的形式及影响因素。玛曲河段沿流向发生网状 河型→弯曲河型→辫状河型的转化现象, 该系列转化呈现出由极稳定河型向极不稳定河型的转化, 这与世界上通 常可以观察到的沿流向不稳定河型向稳定河型转化的情况完全相反。这主要受到地壳的抬升、上下峡谷卡口、水动 力特征、边界沉积物特征及植被的区域分布等因素的控制。托克托附近沿流向发生了弯曲河型→顺直河型转化的 现象, 这是较稳定河型向极稳定河型的转化, 主要受到边界沉积物、水动力等因素的控制。高村上下河段沿流向发 生的辫状河型→弯曲河型转化的现象, 是由极不稳定河型向较稳定河型转化的现象, 河道边界沉积物及水动力是 其主要控制因素, 人工大堤只是限制了河道摆动的最大幅度, 对河型的性质影响不大, 但其上游河段修筑的水库导 致下泻的水流在辫状河段的侵蚀能力增强而使其边界沉积物粗化, 并将泥质物大量沉积在弯曲河段, 客观上促进 了河型的转化。 相似文献
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黄河内蒙古不同河型段对洪水过程的响应特征 总被引：7，自引：0，他引：7
黄河内蒙古河段的河道淤积近年来有所加重,一些人寄望于人造洪峰冲沙来降低河床。本文根据典型年份的最大洪水的流量—水位过程线变化特征,揭示黄河内蒙古不同河型段对这些洪水的响应机制,得出黄河内蒙古河段洪水的流量—水位过程线类型有线形、顺时针环线、逆时针环线3类单一关系和线形+逆时针环线、逆时针环线+线形、"8"字形+线形、嵌套状逆时针环线以及交叉线形5类复合关系。这些关系总体上可以反映洪水过程中河床是侵蚀还是沉积、何时侵蚀何时沉积、以及冲淤是否具有反复性。黄河内蒙古冲积性河段的河道对同一次洪水过程的响应沿程表现出分化现象,其中辫状河段以河床侵蚀下降为特征,弯曲河段以河床明显沉积升高为特征,而顺直河段以少量沉积或冲淤平衡为特征。不同河型段的河道对洪水的响应趋势与洪水动能的沿程减小相适应,洪峰含沙量沿程减小是该趋势的具体体现。人造洪峰冲沙难以逆转上述淤积趋势,对防治洪灾帮助有限。 相似文献
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黄河下游游荡性河道小水致灾研究 总被引：4，自引：0，他引：4
20世纪80年代中期以来,黄河下游游荡性河道的洪水灾害是在下游水量明显减少、洪峰流量也不断减小的情况下发生的。即使是水量比较小的普通洪水,也能造成下游滩区大面积受淹、控导工程决口、桥梁被冲毁、房屋倒塌等严重灾害。小水致灾的形成机理主要是:河道游荡,引发“横河、斜河”;小水淤积,河床抬高,行洪能力下降;人与河床争地,造成滩区阻塞。 相似文献
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黄河下游游荡段河道平面形态与河势变化趋势预测 总被引：6，自引：2，他引：4
黄河下游河道平面形态与河势演变,从20世纪60年代起,地貌界就用地图法和航片资料作过不同程度的研究.随着资料的不断积累,该项研究得到逐步的深化."八五"期间,水利界又对主流线作了深入分析,结果表明:各家所得结论不同,需要作进一步的分析讨论.我们认为:从长远的角度来看,小浪底水库清水下泄期间,黄河下游游荡性河段不对称的河谷形态不会改变;在继承性新构造运动造成的地壳向南掀沉、科氏力和人类活动的综合影响下,主流线总体上仍呈南摆趋势;清水冲刷不会导致河型彻底转化;河道整治工程虽然能够限制主流的摆动幅度和弱化河道的游荡强度,对河势的影响较大,但是根本不可能改变上述河道平面形态的长期演变趋势. 相似文献
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宽变幅水沙两相流的冲淤双临界现象及其地貌学意义 总被引：3，自引：1，他引：3
通过黄土高原一些河流资料的分析，发现了宽变幅水沙两相流冲淤过程中的2个临界值，位于非高含水流区域中的临界点，可称之为冲淤下临界；位于高含沙水流区域中的临界点，可称之为冲淤上临界，水沙两相流冲淤的双临界现象，对珩多沙河流河道泥沙的输移有重要意义，随着含沙量的增大，排沙比先减小而后增大，2次与代表排沙比等于1的直线相交，这2个交点即分别对应于挟沙水流冲淤的下临界和上临界，运用所揭示的水沙两相流冲淤过程的双临界现象，可以对冲积河流河型的形成进行新的解释，以我国近百条冲积河流的资料为基础，点绘了年均悬移质输沙率与年均流量的关系，并以不同的符号来区分弯曲河型、游荡河型和高含沙曲流河型。结果表明，上述3种河型可以很好于被代表特征含沙量分别为C=60kg/m^3和C=3.3kg/m^3的2条直线所区分，这2个特征含沙量反映了河道水沙两相流冲淤的上、下临界值。 相似文献
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黄河下游孟津——陶城埠河道形态特征及新构造的控制作用 总被引：1，自引：0，他引：1
一、河道形态特征 这里所指的河道形态,是指河道宽度、河床坡降、主槽位置的稳定性、河道的弯曲率、大堤间的河道地貌、河流两岸地貌特征等。根据上述特征,可将其分为四段。 (1)孟津——京广铁路桥河段(91公里):黄河出孟津后,河道突然展宽,流势平缓,故在靠近出山口的地方堆积了由粗砂和卵石构造的鸡心滩,再向下游,其沙洲出没无常,河床变换不定,属游荡性河段。 相似文献
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《西部资源》2015,(5)
砂岩型铀矿床主要受地层砂体沉积环境控制。文章从岩性组合、沉积构造、岩石化学成分、粒度分析、砂体规模等多方面研究了含矿地层直罗组的沉积环境特征。直罗组的砂岩具有板状交错层理及槽状交错层理发育,显示其辫状河流相沉积特征;依据粒度分析,存在分支河道及心滩亚相沉积。岩石砂体分选性中等—好,成熟度较高,表明其物源较远,沉积物经过长距离的搬运才沉积下来;由砂岩化学成分铁的含量分析表明直罗组沉积环境为还原环境,后期遭受不同程度后生氧化。因此,本区直罗组沉积环境为还原环境下远源砂质辫状河沉积环境,铀矿化受辫状河的心滩及分支河道亚相砂体控制。具有较好砂岩铀矿成矿地质条件。 相似文献
11.
The Milk River, the northernmost tributary to the Missouri–Mississippi River system, exhibits an anomalous sand-bed braiding reach in an otherwise meandering system. Shortly after leaving Alberta and entering Montana the river suddenly changes to braiding and maintains this pattern for 47 km before entering Fresno Reservoir. Measured stream gradient and bankfull discharge in the braiding reach severely fail the Leopold and Wolman [U.S. Geol. Surv. Prof. Pap. 282B (1957) 39] slope–discharge test for differentiating channel patterns. While channel slope has long been regarded as one of the primary variables associated with braiding, our data from the sand-bed Milk River do not support this relationship. Instead, the data show that the braiding reach has a lower channel slope (0.00047) than the meandering reach (0.00055). Coupled with a constant discharge the unit length stream power is comparable between the two reaches. At the morphologic transition between meandering and braiding, a dramatic reduction in channel bank strength occurs where the sampled silt–clay content declines from 65% in the meandering reach to 18% in the braiding. This enables channel widening which is reflected in a 60% reduction in unit area stream power in the braiding reach. Thus, sediment transport capacity declines and channel bars are deposited. During waning flows, these bars are dissected, producing a braiding morphology. We suggest that for sand-bed braiding rivers the silt–clay percentage in the channel banks may be more important than slope. A review of the original Leopold and Wolman [U.S. Geol. Surv. Prof. Pap. 282B (1957) 39] dataset, and many subsequent analyses, reveals that most braided rivers studied were gravel-bed. As a result, causal variables associated with braiding in sand-bed environments may need a thorough evaluation. 相似文献
12.
以西辽河红山水库修建后上游河道调整为例，说明了除来水来沙等的变化所引起的河流系统调整外，存在由于河流系统可调要素之间的相互联系，相互作用，在水库水位上升后造成的溯源淤积发展中，主、支流河道、上、下游河段冲淤相互影响，槽，滩淤积相互转换，地生态系统调整的影响下，产生的可调要素的复杂多向的调整过程。 相似文献
13.
Fluvial processes of the downstream reaches of the reservoirs in the Lower Yellow River 总被引：1，自引：0，他引：1
Evolution of the river channel downstream of reservoirs is a complex process that is closely related to the operational mode of the reservoirs and the channel boundary conditions. Numerous studies have been carried out on the fluvial processes of downstream reservoirs. However, only a few of them have focused on the relationship between runoff-sediment conditions and channel pattern indicators. Also, the impacts of river training works on fluvial processes are seldom dealt with. In this paper, the evolutionary processes of three sections in the Lower Yellow River, including Tiexie-Yiluo River mouth reach, Huayuankou-Heigangkou reach and Jiahetan-Gaocun reach, were analyzed for variations in the channel boundary line and the mainstream between 1960 and 2015. Channel pattern indicators such as sinuosity, mainstream wandering range and width/depth ratio were analyzed based on field measurements obtained by the Hydrological Department of the Yellow River Conservancy Commission. The effects of river training works on the channel evolution are then described. Since 1960, numerous medium- and large-sized reservoirs have been built on the Yellow River, including Longyangxia Reservoir, Liujiaxia Reservoir and Xiaolangdi Reservoir. These reservoirs impound the runoff from upstream and retain the sediment, which changes the runoff and sediment conditions in the downstream reach. As a consequence, annual runoff and the frequency and peak of flooding have all decreased. As a result, the flow dynamics and their action on the river channel are also reduced, which changes the dynamic state of the river course. The discrimination results obtained using the single parameter discrimination rule and the discrimination equation show that the degree of wandering is weakened in the reaches studied. The variations in the channel pattern indicators show that the sinuosity increases and the wandering range decreases with a reduction in the total annual volume of water. However, the degree of wandering has little relationship to the sediment concentration. In addition, river training works play an important role in controlling the river course. Due to improvements in the river training works, the river course has become more stable under the same runoff and sediment conditions. A new discrimination rule that takes into account the impacts of the river training works is proposed. The discrimination results were found to fit well with the actual river pattern, which shows that the discrimination rule is applicable to the Lower Yellow River. The results show that the runoff and sediment conditions are the most important factors in the evolution of the river course. The river training works have at the same time limited the wandering range of the mainstream and played an important role in the fluvial processes. Both factors combined lead to the stabilization of the river. 相似文献
14.
《地理学报(英文版)》2016,(9)
Evolution of the river channel downstream of reservoirs is a complex process that is closely related to the operational mode of the reservoirs and the channel boundary conditions. Numerous studies have been carried out on the fluvial processes of downstream reservoirs. However, only a few of them have focused on the relationship between runoff-sediment conditions and channel pattern indicators. Also, the impacts of river training works on fluvial processes are seldom dealt with. In this paper, the evolutionary processes of three sections in the Lower Yellow River, including Tiexie-Yiluo River mouth reach, Huayuankou-Heigangkou reach and Jiahetan-Gaocun reach, were analyzed for variations in the channel boundary line and the mainstream between 1960 and 2015. Channel pattern indicators such as sinuosity, mainstream wandering range and width/depth ratio were analyzed based on field measurements obtained by the Hydrological Department of the Yellow River Conservancy Commission. The effects of river training works on the channel evolution are then described. Since 1960, numerous medium- and large-sized reservoirs have been built on the Yellow River, including Longyangxia Reservoir, Liujiaxia Reservoir and Xiaolangdi Reservoir. These reservoirs impound the runoff from upstream and retain the sediment, which changes the runoff and sediment conditions in the downstream reach. As a consequence, annual runoff and the frequency and peak of flooding have all decreased. As a result, the flow dynamics and their action on the river channel are also reduced, which changes the dynamic state of the river course. The discrimination results obtained using the single parameter discrimination rule and the discrimination equation show that the degree of wandering is weakened in the reaches studied. The variations in the channel pattern indicators show that the sinuosity increases and the wandering range decreases with a reduction in the total annual volume of water. However, the degree of wandering has little relationship to the sediment concentration. In addition, river training works play an important role in controlling the river course. Due to improvements in the river training works, the river course has become more stable under the same runoff and sediment conditions. A new discrimination rule that takes into account the impacts of the river training works is proposed. The discrimination results were found to fit well with the actual river pattern, which shows that the discrimination rule is applicable to the Lower Yellow River. The results show that the runoff and sediment conditions are the most important factors in the evolution of the river course. The river training works have at the same time limited the wandering range of the mainstream and played an important role in the fluvial processes. Both factors combined lead to the stabilization of the river. 相似文献
15.
Analysis of controls upon channel planform at the First Great Bend of the Upper Yellow River, Qinghai-Tibet Plateau 总被引：3，自引：3，他引：0
Zhiwei Li Zhaoyin Wang Baozhu Pan Jun Du Gary Brierley Guo-an Yu Brendon Blue 《地理学报(英文版)》2013,23(5):833-848
The 270 km long section of the Upper Yellow River at the First Great Bend is comprised of single channel and multiple channel systems that alternate among anastomosing, anabranching, meandering and braided reaches. The sequence of downstream pattern changes is characterized as： anastomosing-anabranching, anabranching-meandering, meandering-braided and braided-meandering. Remote sensing images, DEM data and field investigations are used to assess ahd interpret controls on these reach transitions. Channel slope and bed sediment size are key determinants of transitions in channel planform. Anas- tomosing reaches have a relatively high bed slope （0.86‰） and coarser sediment bed material （d50 = 3.5 mm）. In contrast, meandering reaches have a low slope （0.30‰） and fine sediment bed material （d50 = 0.036 mm）. The transition from a meandering to braided pattern is characterized by an increase in channel width-depth ratio, indicating the important role of bank strength （i.e. cohesive versus non-cohesive versus channel boundaries）. Interestingly, the braided-meandering and meandering-braided transitions are coincident with variable flow inputs from tributary rivers （Baihe and Heihe rivers respectively）. Theoretical analysis of the meandering-braided transition highlights the key control of channel width-depth ratio as a determinant of channel planform. 相似文献
16.
基于数值模拟的黄河下游 不同情景溃堤洪水特性 总被引：3，自引：2，他引：1
通过研究黄河下游地区的溃堤洪水特性,为防洪减灾工作提供科学依据。本文以黄河下游地区的DEM,1958、1982、1996年典型历史洪水和2000年土地利用数据为模型初始输入,分4个模拟情景,依据黄河溃堤水流的特性,利用二维非恒定流模型对黄河下游不同位置决口情景下的洪水演进特性进行模拟,结果表明:洪水在演进过程中都会侵夺沿途河流行洪,进入下游后洪水会顺河归槽;在同一河段,同一年型洪水北岸不同位置溃口情景所淹没的面积大于南岸对应位置的淹没面积;黄河两岸洪泛区地理位置的差异,使两岸的洪灾程度具有区域差异;水深且流速大的洪水淹没主流区面积相对较小,水浅且流速小的非主流区面积相对较大。 相似文献
17.
黄河口清水沟流路先后经历了游荡型,顺直型和弯曲型和河床演变阶段。与此同时,河流的冲淤变化经历了摆动淤积,造床冲刷和延伸淤积三个阶段,这些变化对河床纵剖面,水位和险情带来了某些较深刻的影响。 相似文献
18.
黄河下游河道输沙功能的时间变化及其原因 总被引：2，自引：4，他引：2
以输出某一河道的泥沙总量与进入这一河道的泥沙量之比来定义河道输沙功能,以此为指标研究了黄河下游输沙功能的时间变化。研究表明,近50年来黄河下游河道输沙功能表现出随时间而减小的明显趋势。在总的减小趋势中,由于水库运用方式与下游水沙组合的不同,河道输沙功能指标具有明显的差异,可以划分为6个阶段。19861997年,由于降水偏少,且人类大量引水,黄河下游进入连续枯水的水文系列,河道萎缩,输沙功能迅速降低,此时段中输沙功能指标的时段平均值为0.62,为有水沙记录以来最低的时期。对于黄河下游输沙功能指标与流域因子和河道特性因子的时间变化系列进行了比较,以揭示输沙功能减小的原因。结果表明,黄河下游河道输沙功能指标与流域平均年降水量、兰州站和三门峡站汛期径流占年径流百分比、游荡段典型断面平滩水位下断面面积、花园口站和高村站水面比降等因子有同步减小的关系,并随流域水土保持面积、人类引水量及其占天然径流量比率的增大而增大,说明这些因子的变化导致了黄河下游输沙功能的减弱。 相似文献