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1.
三峡大坝下游水位变化与河道形态调整关系研究 总被引：8，自引：2，他引：6
三峡水库蓄水利用已有13年,对坝下游洪、枯水位和河道形态调整的影响已初步显现,通过对1955-2016年长江中游水位、河道地形等资料的分析,结果表明：① 坝下游各水文站同流量枯水位下降、洪水位变化不大,最低水位上升,最高水位下降趋势;② 2002年10月-2015年10月枯水河槽冲刷量占平滩河槽冲刷量的95.5%,冲淤分布由蓄水前“冲槽淤滩”转为“滩槽均冲”,不同蓄水阶段存在差异;③ 河槽冲刷过程中,上荆江及以上河段枯水位下降趋势趋缓,下荆江及以下河段下降速率增加,应采取防控措施遏制河道水位下降趋势;④ 枯水河槽冲刷是长江中下游航道水深提升的基础,枯水位降幅小于深槽下切深度,在河道和航道整治工程综合作用下航道尺度提升,提前5年实现了2020年航道尺度规划目标;⑤ 平滩水位以上河槽形态调整不大,在河床粗化、岸滩植被、人类活动等综合作用下河道综合阻力增加,出现了中洪水流量—高水位现象,应引起足够重视。三峡水库汛期调蓄作用可有效提升中下游洪水防御能力,但不排除遭遇支流洪水叠加效应,中下游洪水压力仍然较大。 相似文献
2.
上荆江枯水位对河床冲刷及水库调度的综合响应 总被引：2，自引：0，他引：2
为系统揭示长江中游近期枯水情势及其对三峡水库蓄水的直接和间接响应,本文以冲刷剧烈、枯水位降幅最大的上荆江为例,通过统计其不同形式枯水位的变化特征,建立了水位下降与河床冲刷、水库不同运行方式的相关关系。结果表明,沙市站同流量枯水位几乎与枯水河槽河床平均高程等幅下降,枝城站枯水位下降幅度较小与本底河床形态、河床粗化及航道整治工程有关。上荆江汛前枯水位降幅、最低水位及极枯水位历时等枯水情势会受到三峡水库补水调度的影响,这种补水效应沿程递减,至沙市站补水调度仍然无法抵消河床下切对枯水位造成的影响。 相似文献
3.
重庆主城区河段河道泥沙冲淤事关防洪、航运及码头作业等,是三峡水库泥沙问题的重点内容之一。本文依据原型观测资料,以三峡水库175 m试验性蓄水前后河段的泥沙冲淤规律为基础,结合河床组成分析和一维数学模型,计算提出河段悬移质泥沙走沙基本条件,并应用于减淤调度实践中。结果表明：① 三峡水库175 m试验性蓄水后至2012年重庆主城区河段河床冲刷强度下降,主走沙期推迟至汛前消落期,2013年后上游来沙减少使得河床冲刷强度再次增大;② 当寸滩站流量大于4000 m 3/s、坝前水位低于167 m时,河段开始走沙;当寸滩站流量增大至超过5000 m 3/s、坝前水位下降至163 m时,河段走沙能力增强;加大水库自163 m水位的消落速度,能够避免库尾河段产生累积性淤积。 相似文献
4.
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
5.
洞庭湖环境系统变化对水文情势的响应 总被引：11，自引：2，他引：9
为全面揭示洞庭湖近数十年的水情异常与成因,将湖区视作一个大系统来研究。经水位~流量关系等多种方法研究表明：(1)入湖四水尾闾同水位流量减少1 200~2 800 m3/s,同流量水位抬高0.49~1.28 m;(2) 荆江三口分水比减少19.2%,分沙比减少25.1%;(3) 澧水、松滋、南洞庭湖等主洪道的水位流量关系均发生了较大变化;(4) 天然调蓄能力下降40%,湖口同流量水位抬高1.80~2.50 m;(5) 7~8月湖垸关系常处于危急状态。其主要原因是泥沙淤积恶性循环,导致了湖泊环境系统功能的变化,而由下荆江3处裁弯所引起的江湖水沙调整则加速了其变化过程。这些变化过程对水情的复合响应是：入湖水沙呈逐渐减少趋势变化,洪水位普遍抬高1.50~1.80 m,湖口有时出现江水倒流,洪水涨率增大,高洪水位持续时间长等异常水文现象,且给湖区造成了巨大的洪水压力。 相似文献
6.
探讨了全国重点防洪城市长沙市防洪建设中的若干重要问题:防洪标准、设计洪水位、防洪大堤高度等的确定;建设方针与程序、整体防洪能力建设、防洪建设与基础设施建设和景观建设协调发展等。长沙设计洪水位的确定应综合考虑以下几个方面:湘江长沙段洪水与其支流和东洞庭湖洪水不存在高标准洪水同期遭遇问题,更不存在同频率洪水遭遇问题;湘江洪水流量与水位关系不是长沙洪水设计的主要依据;而南洞庭湖洪水位顶托和河道槽蓄量减少是影响长沙洪水位高低的动、静态因素。目前,长沙城市堤防设防高度偏高,减少了大堤的稳定性,造成了无效投资,影响了城市景观。防洪工程建设应分期实施、先除险后加固、注重整体防洪能力的提高,并处理好与城市基础设施建设和景观建设的关系。 相似文献
7.
利用地理信息系统(GIS)与数字高程模型(DEM)技术,定量分析了30年来东平水道上段河道演变过程,结果表明:河道总体有冲刷的趋势,其中1977-1990年冲刷量为660X104m3,平均冲刷速率为50×104m3/a:1990-1999年冲刷量为0025x108 m3,平均冲刷速率为270x104 m3/a:20世纪90年代变化强度大于80年代.东平水道上段河床下切幅度不一,沿程下切幅度先增大后减小再增大;深泓线在河口到三水区段从河道右岸向左岸偏转,从三水区到紫洞段,深泓线位置较为稳定.河床地形的剧烈变化引起了河道水动力的变化,如水位大幅下降,水位流量曲线变化,思贤滘分流比变化等.大规模无序挖沙和航道整治是引起东平水道上段河道演变的主要原因. 相似文献
8.
采取工程措施调整干流上、中、下游区水量泄放比例,完成塔里木河流域综合治理工程项目,实现塔里木河的综合治理生态河流目标。由于中游河道比降小、砂质河岸极易侵蚀,河床宽浅,河道行洪能力低下;该段是塔里木河冲积平原南北伸展最宽的地段,是塔里木河河道泛滥地段,洪水使河道改道频繁。为进一步论证塔里木河中游河段控制型拦河枢纽工程对上下游河段堤防和两岸生态闸的影响,进行塔里木河中游拟建枢纽工程上下游河段内的水文要素观测、测量实验分析,掌握河段各项水文要素变化特征,分析河段内洪水的水面线、糙率的变化情况和中游河段的年径流量、最大洪峰流量、泥沙含量、输沙量等水文要素衰减率,以及河道内断面冲淤变化等问题,是为进一步研究洪水冲刷对堤防、水利工程影响的基本资料,是流域综合治理工程项目论证工作的必要条件。 相似文献
9.
大型水库的兴建深刻改变了下游水沙输移特点,进而导致河床演变规律显著调整,水库下游弯曲河型对水沙过程改变响应敏感,是水库下游河床演变、航道整治、河势控制等方面研究的关键区域。本文基于1996-2016年的实测水文、地形资料,对长江三峡水库下游弯曲河型的演变规律及其驱动机制开展研究,结果表明：① 三峡水库蓄水前,下荆江存在“凸淤凹冲”、“凸冲凹淤”两类弯曲河型,而三峡水库蓄水后均表现为“凸冲凹淤”的一致性规律;② 在水库拦沙作用的影响下,下荆江河段平滩河槽存在累积性冲刷现象,冲刷部位集中于枯水河槽与基本河槽之间的低滩,冲淤部位调整主要由变化的流量过程所驱动,上游河势、河道边界以及支流入汇等因素均有一定驱动作用;③ 在三峡水库蓄水后缺乏大洪水的情况下,凸岸水流挟沙力随流量增加逐渐增强,水流对凸岸冲蚀力度在平滩流量级附近（20000~25000 m3/s）达到最强,平滩流量附近流量级的持续时间超过20天时,弯曲河道发生凸冲凹淤现象。而悬沙中造床粗沙的减少,增强了水流冲刷强度,加剧了凸岸的冲蚀程度。 相似文献
10.
珠江三角洲网河区水文与地貌特征变异及其成因 总被引：37，自引：1，他引：37
采用珠江三角洲网河区数十年来的人类活动和水文特征资料，通过分析人类活动的水文响应特征，发现该地区近10年多来水文情势发生了显著异变。主要表现在河道人工采砂以及大洪水冲刷导致河床下芬，部分断面水位－流量关系异变。部分河段冲淤特征倒转，汊河分水分沙比发生变化。围垦，臾，码头建设以及水闸的不合理调度使得水量集中，蓄滞洪能力减小，河道流量增加。三角洲上部河床剧烈下切，汇流速度加快；而口门多呈淤只状态，加之海平面上升，潮流顶托阻水，三角洲腹地水位抬升，洪涝威胁加剧。剧烈人类活动是珠江三角洲网河区水文与地貌特征变异的直接原因。 相似文献
11.
CHAI Yuanfang YANG Yunping DENG Jinyun SUN Zhaohua LI Yitian ZHU Lingling 《地理学报(英文版)》2020,30(10):1633-1648
The operation of large-scale reservoirs have modified water and sediment transport processes, resulting in adjustments to the river topography and water levels. The polynomial fitting method was applied to analyze the variation characteristics of water levels under different water discharge values in the Jingjiang reach of the Yangtze River from 1991–2016. The segregation variable method was used to estimate the contributions of the varied riverbed evaluation, the downstream-controlled water level, and the comprehensive roughness on the altered water level at an identical flow. We find that low water levels in the Jingjiang reach of the Yangtze River from 1991–2016 are characterized by a significant downward trend, which has intensified since 2009. Riverbed scouring has been the dominate factor causing the reduced low water level while increased roughness alleviated this reduction. From 1991–2016, there was first a decrease followed by an increase in the high water level. The variation characteristic in terms of the "high flood discharge at a high water level" before 2003 transformed into a "middle flood discharge at a high water level" since 2009. The increased comprehensive roughness was the main reason for the increased high water level, where river scouring alleviated this rise. For navigation conditions and flood control, intensified riverbed scouring of the sandy reaches downstream from dams enhanced the effects that the downstream water level has on the upstream water level. This has led to an insufficient water depth in the reaches below the dams, which should receive immediate attention. The alteredvariation characteristics of the high water level have also increased the flood pressure in the middle reaches of the Yangtze River. 相似文献
12.
In this study, data measured from 1955-2016 were analysed to study the relationship between the water level and river channel geometry adjustment in the downstream of the Three Gorges Dam (TGD) after the impoundment of the dam. The results highlight the following facts: (1) for the same flow, the low water level decreased, flood water level changed little, lowest water level increased, and highest water level decreased at the hydrological stations in the downstream of the dam; (2) the distribution of erosion and deposition along the river channel changed from “erosion at channels and deposition at bankfulls” to “erosion at both channels and bankfulls;” the ratio of low-water channel erosion to bankfull channel erosion was 95.5% from October 2002 to October 2015, with variations between different impoundment stages; (3) the low water level decrease slowed down during the channel erosion in the Upper Jingjiang reach and reaches upstream but sped up in the Lower Jingjiang reach and reaches downstream; measures should be taken to prevent the decrease in the channel water level; (4) erosion was the basis for channel dimension upscaling in the middle reaches of the Yangtze River; the low water level decrease was smaller than the thalweg decline; both channel water depth and width increased under the combined effects of channel and waterway regulations; and (5) the geometry of the channels above bankfulls did not significantly change; however, the comprehensive channel resistance increased under the combined effects of riverbed coarsening, beach vegetation, and human activities; as a result, the flood water level increased markedly and moderate flood to high water level phenomena occurred, which should be considered. The Three Gorges Reservoir effectively enhances the flood defense capacity of the middle and lower reaches of the Yangtze River; however, the superposition effect of tributary floods cannot be ruled out. 相似文献
13.
The geological and meteorological setting of the Jianghan–Dongting lake area leads to high precipitation and siltation, but poor water discharge, thus the area is frequently flooded. In the past the river–lake relationship of the Middle Yangtze has been variable but has deteriorated recently under increasing human influence. The Jianghan Plain of the Middle Yangtze becomes a waterlogged lowland under the constant threat of flooding from the perched Jingjiang River. Due to siltation and land reclamation the Dongting Lake has lost most of its regulatory function for the river and has become increasingly vulnerable to flood disasters. The Middle Yangtze River has been undergoing siltation, resulting from a downstream decline of sediment transport capacity, resulting in the elevation of the flood level above the lowlands. Heightening of the levees has caused further siltation of the channel.The Three Gorges Reservoir will provide a buffering period of 50–80 years, during which much of the silt will be trapped in the reservoir and scouring downstream may occur. We should utilize this period to work out an overall resolution to the problem. Construction of a water and silt diversion project in the Honghu Lake and surrounding areas may resolve this problem in the dangerous Chenglingji–Wuhan Segment of the Yangtze. Widening the canals connecting the Middle Yangtze and Han Rivers may function as a discharge-dividing channel of the Yangtze, which may prove to be beneficial. 相似文献
14.
大量采沙对东江下游及东江三角洲河床地形和潮汐动力的影响 总被引：10，自引：0，他引：10
通过分析东江下游及东江三角洲的采沙情况、采沙对河床演变和潮汐动力的影响。近几十年来东江下游及东江三角洲采沙量巨大,1980~2002年22年间采沙总量达到了3.32亿m3。大量采沙对河床演变的主要影响是：大幅度扩大了河槽容积、河床平均高程显著降低、水深明显增加、纵比降减小。东江下游及东江三角洲潮汐动力的变化主要表现在：网河区上段及东江下游潮水位明显降低,潮差增大,涨潮历时延长,主要分潮振幅加大;潮汐传播速度加快;潮区界、潮流界、咸潮界上移;网河区上段及东江下游潮汐动力得到明显增强,潮汐动力作用范围向上延伸,导致这种变化的主要原因是大量挖沙所导致的河床剧烈变化。 相似文献
15.
The sand dredging and its impacts on riverbed evolution and tidal dynamic change in the lower reaches and delta of the Dongjiang River are examined in this paper. The large amount of sand, totally 3.32 billion m3 from 1980 to 2002, was mined from the riverbeds of the lower reaches and delta of the Dongjiang River. Increasing of the channel capacity, lowering of the average riverbed elevation, deepening of the water depth and decreasing of the longi-tudinal riverbed gradient are the main effects on the riverbed evolution brought by the large amount of sand dredging. Under the strong sand dredging and associated significant riverbed deformation, the notable changes of the tidal dynamic in the lower reaches and delta of the Dongjiang River occurred, including: (1) in the upper reaches of the Dongjiang River delta and lower reaches of the Dongjiang River, tidal level dropped apparently, tidal range widened, flood tidal duration became longer, amplitudes for major tidal components became bigger and tidal dynamics intensified; (2) tidal wave spread faster; and (3) the limits of the tidal level, tidal current and salt water moved upstream. 相似文献
16.
《地理学报(英文版)》2010,(5)
Based on the measured hydrological data from 1951 to 2008,the chain hydrological effect between Jingjiang River and Dongting Lake is analyzed by comparative method after the Three Gorges Project operation.The result indicates that 1) the scouring amount in Jingjiang River made up 78.9% of the total from Yichang to Chenglingji,and its average scouring intensity was higher than the latter;2) the water and sand diversion rates at the three outlets of the Jingjiang River were reduced by 2.33% and 2.78% separately;3) the proportion of multi-year average runoff and sediment through the three outlets in the total into the Dongting Lake decreased by 7.7% and 24.4% respectively;4) in Dongting Lake,the speed of sediment accumulation was lowered by 26.7%,in flood season,the runoff amount was 20.2% less than the multi-year average value,leading to seasonal scarcity of water year by year.The former prolonged the lake life,while the latter induced droughts in summer and fall in successive years,shortage of drinking and industrial water,shipping insecurity,as well as ecological problems such as decrease of birds and quick increase of Microtus fortis;5) The multi-year average values of sediment and flood transporting capacity at the lake outlet were respectively increased by 26.6% and 3.7%,the embankments were protected effectively.Then,to adapt to the new change of the river-lake relation,some suggestions were put forward,such as optimizing further operation program of the Three Gorges Reservoir,reexamining the idea of river and lake regulation,and maintaining connection of the river and the lake. 相似文献
17.
随着黄河上游控制性水利枢纽相继投入运用,黄河内蒙古段河道冲淤演变格局得到重塑。利用水文站实测数据,系统分析了海勃湾水利枢纽建设运行前后坝后河道水沙变化特征。基于河道断面高程数据,从滩槽冲淤（横向）及沿程冲淤（纵向）两方面定性分析坝后河道形态变迁,采用断面地形法定量计算坝后河道冲淤变化量。结果表明：海勃湾水利枢纽蓄水运用后,坝后河道的水沙搭配条件显著改善,来沙系数、单位径流量的输沙量降幅较大,对坝后河道减淤冲刷作用明显。坝后河道横纵断面变迁以冲刷为主,冲淤演变过程经历了淤积（2004—2012年）、冲淤过渡（2012—2014年）、冲刷（2014—2020年）3个阶段。 相似文献
18.
Mechanisms of suspended sediment restoration and bed level compensation in downstream reaches of the Three Gorges Projects (TGP) 总被引：3，自引：2，他引：1
Wei Zhang Yunping Yang Mingjin Zhang Yitian Li Lingling Zhu Xingying You Dong Wang Junfeng Xu 《地理学报(英文版)》2017,27(4):463-480
River basin reservoir construction affects water and sediment transport processes in downstream reaches. The downstream impact of the Three Gorges Projects (TGP) has started to become apparent: (1) reduction in flood duration and discharge, and significant reduction in sediment load. Although there was some restoration in downstream sediment load, the total amount did not exceed the pre-impoundment annual average; (2) in 2003–2014, the d > 0.125 mm (coarse sand) load was restored to some degree, and to a maximum at Jianli Station, which was mainly at the pre-impoundment average. After restoration, erosion and deposition characteristics of the sediment was identical to that before impoundment. The degree of restoration during 2008–2014 was less than during 2003–2007; (3) after TGP impoundment, there was some restoration in d < 0.125 mm (fine sand) sediment load, however, it was lower than the pre-impoundment average; (4) due to riverbed compensation, the d > 0.125 mm sediment load recovered to a certain degree after impoundment, however, the total did not exceed 4400×104 t/y. This was mainly limited by flood duration and the average flow rate, and was less affected by upstream main stream, tributaries, or lakes. Restoration of d < 0.125 mm suspended sediment was largely controlled by upstream main stream, tributaries, and lakes, as well as by riverbed compensation. Due to bed armoring, riverbed fine suspended sediment compensation capability was weakened; (5) during 2003–2007 and 2008–2014, Yichang to Zhicheng and upper Jingjiang experienced coarse and fine erosion, lower Jingjiang experienced coarse deposition and fine erosion, Hankou to Datong had coarse deposition and fine erosion, and Chenglingji and Hankou was characterized by coarse deposition and fine sand erosion in 2003–2007, and coarse and fine erosion in 2008–2014. This difference was controlled by flood duration and number at Luoshan Station. 相似文献