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1.
It is of necessity to investigate the adjustment of flood discharge capacity in the Lower Yellow River(LYR) because of its profound importance in sediment transport and flood control decision-making, and additionally its magnitude is influenced by the channel and upstream boundary conditions, which have significantly varied with the ongoing implementation of soil and water conservation measures in the Loess Plateau and the operation of the Xiaolangdi Reservoir. The braided reach between two hydrometric stations of Huayuankou and Gaocun in the LYR was selected as the study area. Different parameters in the study reach during the period 1986–2015 were calculated, covering bankfull discharge(the indicator of flood discharge capacity), the pre-flood geomorphic coefficient(the indicator of channel boundary condition), and the previous five-year average fluvial erosion intensity during flood seasons(the indicator of incoming flow and sediment regime). Functional linkages at scales of section and reach were then developed respectively to quantitatively demonstrate the integrated effects of channel and upstream boundary conditions on the flood discharge capacity.Results show that:(1) the reach-scale bankfull discharge in the pre-dam stage(1986–1999)decreased rapidly by 50%, accompanied with severe channel aggradation and main-channel shrinkage. It recovered gradually as the geometry of main channel became narrower and deeper in the post-dam stage, with the geomorphic coefficient continuously reducing to less than 15 m-1/2.(2) The response of bankfull discharge to the channel and upstream boundary conditions varied at scales of section and reach, and consequently the determination coefficients differed for the comprehensive equations, with a smallest value at the Jiahetan station and a highest value(0.91) at reach scale. Generally, the verified results calculated using the comprehensive equations agreed well with the corresponding measured values in 2014–2015.(3) The effect of channel boundary condition was more prominent than that of upstream boundary condition on the adjustment of bankfull discharge at the Jiahetan station and the braided reach, which was proved by a larger improvement in determination coefficients for the comprehensive equations and a better performance of geomorphic coefficient on the increase of bankfull discharge. 相似文献
2.
近60年黄河水沙变化及其对三角洲沉积的影响 总被引：1，自引：1，他引：0
In order to find out the variation process of water-sediment and its effect on the Yellow River Delta, the water discharge and sediment load at Lijin from 1950 to 2007 and the decrease of water discharge and sediment load in the Yellow River Basin caused by human disturbances were analyzed by means of statistics. It was shown that the water discharge and sediment load into the sea were decreasing from 1950 to 2007 with serious fluctuation. The human activities were the main cause for decrease of water discharge and sediment load into the sea. From 1950 to 2005, the average annual reduction of water discharge and sediment load by means of water-soil conservation practices were 2.02×109 m3 and 3.41×108 t respectively, and the average annual volume by water abstraction for industry and agriculture were 2.52×1010 m3 and 2.42×108 t respectively. The average sediment trapped by Sanmenxia Reservoir was 1.45×108 t from 1960 to 2007, and the average sediment retention of Xiaolangdi Reservoir was 2.398×108 t from 1997 to 2007. Compared to the data records at Huanyuankou, the water discharge and sediment load into the sea decreased with siltation in the lower reaches and increased with scouring in the lower reaches. The coastline near river mouth extended and the delta area increased when the ratio of accumulative sediment load and accumulative water discharge into the sea (SSCT) is 25.4–26.0 kg/m3 in different time periods. However, the sharp decrease of water discharge and sediment load into the sea in recent years, especially the Yellow River into the sea at Qing 8, the entire Yellow River Delta has turned into erosion from siltation, and the time for a reversal of the state was about 1997. 相似文献
3.
Evolution of sedimentary environments of the middle Jiangsu coast, South Yellow Sea since late MIS 3 总被引：3，自引：0，他引：3
Fei Xia Yongzhan Zhang Qiang Wang Yong Yin Karl W. Wegmann J. Paul Liu 《地理学报(英文版)》2013,23(5):883-914
An evolutionary model of sedimentary environments since late Marine Isotope Stage 3 （late MIS 3, i.e., ca. 39 cal ka BP） along the middle Jiangsu coast is presented based upon a reinterpretation of core 07SR01, new correlations between adjacent published cores, and shallow seismic profiles recovered in the Xiyang tidal channel and adjacent northern sea areas. Geomorphology, sedimentology, radiocarbon dating and seismic and sequence stratigraphy are combined to confirm that environmental changes since late MIS 3 in the study area were controlled primarily by sea-level fluctuations, sediment discharge of paleo-rivers into the South Yellow Sea （SYS）, and minor tectonic subsidence, all of which impacted the progression of regional geomorphic and sedimentary environments （Le., coastal barrier island freshwater lacustrine swamp, river floodplain, coastal marsh, tidal sand ridge, and tidal channel）. This resulted in the formation of a fifth-order sequence stratigraphy, comprised of the parasequence of the late stage of the last interstadial （Para-Sq2）, including the highstand and forced regressive wedge system tracts （HST and FRWST）, and the parasequence of the postglacial period （Para-Sql）, including the transgressive and highstand system tracts （TST and HST）. The tidal sand ridges likely began to develop during the postglacial transgression as sea-level rise covered the middle Jiangsu coast at ca. 9.0 cal ka BP. These initially submerged tidal sand ridges were constantly migrating until the southward migration of the Yellow River mouth to the northern Jiangsu coast during AD 1128 to 1855. The paleo-Xiyang tidal channel that was determined by the paleo-tidal current field and significantly different from the modern one, was in existence during the Holocene transgressive maxima and lasted until AD 1128. Following the capture of the Huaihe River in AD 1128 by the Yellow River, the paleo-Xiyang tidal channel was infilled with a large amount of river-derived sediments from AD 1128 to 1855, causing the emergence of some of the previously submerged tidal sand ridges. From AD 1855 to the present, the infilled paleo-Xiyang tidal channel has undergone scouring, resulting in its modern form. The modern Xiyang tidal channel continues to widen and deepen, due both to strong tidal current scouring and anthropogenic activities. 相似文献
4.
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
5.
《地理学报(英文版)》2016,(9)
The Inner Mongolia reaches of the Yellow River face problems of severe sedimentation caused by a variety of complex factors. The sedimentation process in those reaches has been characterized using the sediment balance method, and the key factors affecting the process have been analyzed using the correlation analysis method. The results show that during the period 1952–2012 the Bayangaole(Bayan Gol) to Toudaoguai reaches in Inner Mongolia have undergone successive processes of accumulative sedimentation, then relative balance, and then accumulative sedimentation once again. The total annual sedimentation is 12.0341×10~8 m~3, of which accumulations from July to October account for 95.1% and the reaches from Sanhuhekou to Toudaoguai account for 98.5%. The main factor affecting scouring and sedimentation of the Bayangaole to Sanhuhekou reaches is the combined water and sediment condition. The critical conditions for equilibrium are an incoming sediment coefficient 0.007 kg·s·m~(–6) and a flow discharge 700 m~3·s~(–1). The main factor affecting scouring and sedimentation of the Sanhuhekou to Toudaoguai reaches is the incoming sediment from the tributaries on the south bank and the combined water and sediment condition of the main stream. The critical conditions of the main stream for maintaining equilibrium status are a flow discharge of the main stream exceeding 800 m~3·s~(–1) and a comprehensive incoming sediment coefficient 0.005 kg·s·m~(–6). The incoming sediment from the tributaries has little impact on the main stream when the annual sediment load is less than 0.1×10~8 t. The incoming sediment coefficient of the main stream and the incoming sediment from the tributaries both play vital roles in the riverbed evolution of the Inner Mongolia reaches, but the latter contributes the most. 相似文献
6.
Delayed response behaviour commonly occurs in conjunction with changes in riverbed scouring and sediment deposition and is a key component in understanding the intrinsic behaviour of reservoir siltation. Due to the complexity of the riverbed siltation process, the variability in the factors that influence siltation and the limitations of available research methods, the understanding of the delayed response behaviour of the sedimentation process in the Three Gorges Reservoir(TGR) is currently mer... 相似文献
7.
This paper focuses on the growth response of Caragana microphylla seedlings to changes of artificially controlled water table in Horqin Sandy Land, China. Monitoring results of soil water content shows that soil moisture is closely correlated to groundwater depths. Soil volumetric water increased rapidly when close to water sources and finally stabilized in a saturated state. The soil moisture trend of CK(control) increased gradually at 0–50 cm of soil depth then decreased to 4% below 50 cm soil depth. C. microphylla can adapt to different soil environments by changes in ecological and physiological characteristics. By comparing the ecological characteristics of C. microphylla seedlings at various water tables, we found that a shallow water table of 40 cm depth inhibited seedling growth because of weak ecological characteristics. A groundwater depth of 120 cm was more advantageous for plant height and canopy growth of C. microphylla seedlings. During the first two years, the most suitable water depth for root biomass was 120 cm, and 180 cm for root length. The growth of vertical roots is positively correlated with groundwater depth, and root thickness is the determinate factor for root biomass while the fine root is the determinate factor for root length. A thick root would grow much more in a natural drought environment while access to ground water promotes the growth of fine roots. 相似文献
8.
长江中游马口-田家镇河段40年来河道演变 总被引：2，自引：1，他引：1
Quantitative analysis was performed on the filling-scouring process for the river reach within Makou and Tianjiazhen, the middle Yangtze River with the help of GIS and DEM techniques. The research results indicate that the river reach between Makou and Tianjiazhen was dominated by the scouring process, and the magnitude of scouring is increasing over time. The intensity of scouring process is more in the deep and narrower river reach than shallower and wider ones. The river reach in the Makou and Tianjiazhen river knot is in fre-quent scouring and filling process, however the river reach upper to the Makou and lower to the Tianjiazhen river knot is in moderate scouring and filling process. The river reach just upstream or downstream to the river knot (e.g. Makou and Tianjiazhen river knot in this research) is dominated by filling process and the river reach in the river knot is dominated by the scouring process. Research results indicate no changes in the boundary of the river but the scouring and the filling magnitude in specific river channel is strong. The filling and the scouring process of the study river reach is greatly impacted by the sediments and water from the upstream of the study river reach. The construction of the Three Gorges Dam just upstream to Yichang will cause further decrease of the release of the sediment load to the middle and the lower Yangtze River basin, which will further intensify the scouring process of the river channel in the study river reach. 相似文献
9.
The accumulation and ablation of a glacier directly reflect its mass income and wastage, and ice temperature indicates glacier＇s climatic and dynamic conditions. Glaciological studies at Baishui Glacier No.1 in Mt. Yulong are important for estimating recent changes of the cryosphere in Hengduan Mountains. Increased glacier ablation and higher ice temperatures can cause the incidents of icefall. Therefore, it is important to conduct the study of glacier mass balance and ice temperature, but there are few studies in relation to glacier＇s mass balance and active-layer temperature in China＇s monsoonal temperate glacier region. Based on the field observations of mass balance and glacier temperature at Baishui Glacier No.1, its accumulation, ablation, net balance and near-surface ice temperature structure were analyzed and studied in this paper. Results showed that the accumulation period was ranged from October to the following mid-May, and the ablation period occurred from mid-May to October, suggesting that the ablation period of temperate glacier began about 15 days earlier than that of continental glaciers, while the accumulation period began about 15 days later. The glacier ablation rate was 6.47 cm d 1 at an elevation of 4600 m between June 23 and August 30, and it was 7.4 cm d 1 at 4800 m between June 26 and July 11 in 1982, moreover, they respectively increased to 9.2 cm d 1 and 10.8 cm d 1 in the corresponding period and altitude in 2009, indicating that glacier ablation has greatly intensified in the past years. The temperature of the main glacier body was close to melting point in summer, and it dropped from the glacier surface and reached a minimum value at a depth of 4-6 m in the ablation zone. The temperature then rose to around melting point with the depth increment. In winter, the ice temperature rose gradually with the increasing depth, and close to melting point at the depth of 10 m. Compared with the data from 1982, the glacier temperature has risen in the ablation zone in recent decades. 相似文献
10.
The stratigraphical cross-sections of the Yangtze River incised-valley near the No.1,No.3 and No.4 Nanjing Yangtze River bridges were established with respective bore date and documents.By 14C age analysis of the samples of four drilling cores near the No.4 Bridge(to be built),we can find that the time range of paleo-valley is dated in the LGM at a depth of-60 m to-90 m near Nanjing.It is also indicated that the deep incised-valley channel was narrow and the river flowed swiftly.The ancient Yangtze River deep channel presented partially and deeply incised features near the No.1 Bridge.According to previous publications,much research has been done on the main paleo-channel of the Yangtze River,but few results have been achieved on discharge estimation.In this paper,the incipient velocity and average velocity of the LGM was calculated with Vc = 4.60 d 1/3 h1/6,95 Vc 1.28lg 13.15.h.gd,d = 6 * 90 V 6.5u h≈ d,etc.,in terms of the river shape,sedimentary grain size and sequences near the No.3 and No.1 bridges.Moreover,the discharge in Nanjing reach of the Yangtze River during the LGM has been estimated to be around 12,000-16,000 m3/s according to the relationship of discharge,velocity of flow and cross-section. 相似文献
11.
基于黄河下游1986-2015年的水沙和沿程实测大断面数据等资料,统计分析了小浪底水库运行前后下游主槽断面形态参数（河宽、水深、河相系数）的调整过程。结果表明：1986-1999年小浪底运行前主槽持续淤积萎缩,主槽河宽和水深均减小,河宽与水深调整强度高村以上段河宽大于水深、断面河相系数明显减小,高村以下段河宽小于水深、河相系数小幅增加;2000-2015年小浪底水库运行后主槽持续冲刷,主槽河宽和水深增加,沿程各段水深调整强度均大于河宽,河相系数减小;各段断面形态调整方式淤积期表现为艾山以上游荡段和过渡段既有横向萎缩又有垂向淤高、艾山以下弯曲段以垂向淤高为主,冲刷期游荡段和过渡段为横向展宽和垂向冲深、弯曲段以垂向冲深为主;河宽淤积期减小速率明显大于冲刷期增加速率,水深淤积期减小速率略小于冲刷期增加速率,经过一轮淤积和冲刷后,断面形态向窄深方向发展;主槽断面形态调整规律与水沙条件密切相关,断面河相系数除游荡段淤积期与流量呈正相关、与含沙量呈负相关外,游荡段冲刷期、过渡段和弯曲段淤积与冲刷不同阶段,河相系数与流量呈负相关,与含沙量呈正相关。 相似文献
12.
准确把握环境变化下前期水沙条件对当前河床形态调整的影响,建立非平衡态河床形态调整的模拟方法,对深化河床非平衡调整过程的认识至关重要。基于黄河下游花园口—利津河段1965—2015年的水沙和沿程82个大断面数据,首先统计分析了不同河段主槽断面形态参数（面积、河宽、水深和河相系数）的调整过程及其对水沙变化的响应规律;进而以水沙因子作为主槽断面形态调整的主控因素,采用滞后响应模型的多步递推模式,建立了其对前期水沙条件变化的滞后响应模型。结果表明,各河段面积、河宽和水深经历了减小—增加—减小—增加的变化过程,并且其与4 a滑动平均流量和含沙量之间分别呈正相关和负相关;而河相系数孙口以上段整体减小,孙口以下段呈增加—减小—增加—减小的变化过程,除花高段1965—1999年外,其与流量呈负相关,与含沙量呈正相关。滞后响应模型在黄河下游主槽断面形态对前期水沙条件响应过程的应用表明,各参数模型计算值与实测值符合程度均较高,模型能够很好地模拟主槽断面形态对水沙变化的响应调整过程,模型计算结果显示主槽断面形态调整受当年在内的前8 a水沙条件的累积影响,当年和前7 a水沙条件对当前断面形态的影响权重分别约为30%和70%。本文模型有助于深化前期水沙条件对当前河床形态调整影响机理的认识,并为未来不同水沙情形下主槽断面形态的预测提供了有效计算方法。 相似文献
13.
黄河下游清水冲刷阶段河床的调整及其对基准面变化的反应 总被引：1，自引：1，他引：0
本文采用黄河下游的实测资料,分析了三门峡水库下洩清水阶段,河床的调整及其对基准面的反应。认为在来水来沙条件变化的情况下,河床纵剖面以近于平行的方式调整;横断面形态向窄深式发展;河型的转化主要取决于地貌临界值和粉沙—粘土含量。从长时间看,下游的淤积特性不会发生根本性的变化。 相似文献
14.
黄河下游河道断面形态参数变化及其水沙过程响应 总被引：1，自引：0，他引：1
基于1965—2015年黄河下游花园口、高村、泺口站的逐年水文和汛前河道断面的实测资料，分析了河道断面形态参数（河道断面面积，河道宽深比等）的变化，以及对河道断面形态与来水来沙间的关系做出定量化分析。结果表明：主槽断面形态参数与水沙搭配以及前期断面形态密切相关，沿程3个断面形态参数调整方式存在显著差异。河宽调整幅度沿程减小，辫状河段变幅最大，尤其在1986—1999年，辫状河段萎缩程度最为严重，其次为弯曲河段，顺直河段横向调整幅度最小。受到前期断面形态的影响，辫状河段河道断面调整方式既有横向展宽（萎缩）又有垂直加深（淤积）；弯曲河段河道宽深比与流量呈较弱的正相关关系，具有横向和垂向的调整方式；而顺直河段的宽深比与流量呈负相关关系，与来沙系数呈正相关关系，河道以垂直加深（淤积）为主。 相似文献
15.
对黄河内蒙古段河道大断面进行了连续4 a的测量,分析了断面泥沙冲淤与形态调整的变化过程;通过对河床形态指标变化与水沙条件的相关分析,揭示了河床调整主要的影响因素。结果显示：近4 a内不存在河槽萎缩的现象,整个河段河道存在总的冲刷降低的趋势,继承了自2004年以来该段河道以深度加大为主,河槽逐渐缓慢扩大的变化方向。整个河段平均从2011年汛后至2014年汛后,全断面冲刷了64 m2,河槽河底降低了0.16 m,河槽断面面积增加了4.4%,平均深度增加了4.9%,河槽宽度只增加了0.88%,河槽宽深比减小了4.8%。河槽冲刷和形态调整主要发生在2011年汛后至2012年汛后期间,与2012年较大的洪峰有关。分析河槽冲淤和断面形态变化与水沙条件的关系,结果显示滩唇高度、河槽过水面积、平均深度及宽深比变率与流量大小关系密切。滩唇高度、河槽过水面积、平均深度随着流量的增大而增加,宽深比随着流量的增大而减小。相反,河床断面面积和主槽宽度的变化与水沙条件的关系不显著。除了滩唇高度与平均含沙量有关外,平均含沙量和来沙系数与河床冲淤以及河槽形态变化之间关系都不显著。揭示出近年来内蒙河道主槽以垂向冲淤为主,并且流量变化控制着河槽冲淤与形态调整过程。 相似文献
16.
提高黄河下游游荡段的输沙能力是河道治理的主要任务,而河道输沙效率（排沙比）受到来水来沙条件和河床边界条件的共同影响。本文基于1971—2016年花园口—高村河段（简称花高段）的实测水沙及地形资料,计算了花高段的平均河相系数及水沙条件（来沙系数和水流冲刷强度）,从汛期和场次洪水2个时间尺度,定量分析了排沙比与水沙条件及前一年汛后主槽形态之间的响应关系。分析结果表明：① 汛期和场次洪水排沙比与来沙系数呈负相关,与水流冲刷强度呈正相关,临界的汛期不淤来沙系数为0.012 kg?s/m 6,场次洪水排沙比与来沙系数及水量比的决定系数为0.76;② 游荡段排沙比与河相系数呈负相关,当河相系数大于15 /m 0.5时,河段排沙比基本小于1;③ 以来沙系数与河相系数为自变量的汛期排沙比计算式的决定系数为0.82,计算精度较高,对于场次洪水排沙比而言,断面形态的影响权重大于来沙系数。这些排沙比计算公式能够反映游荡段的输沙特点,有助于定量掌握断面形态及水沙条件对河道输沙能力的影响。 相似文献
17.
黄河内蒙河段河床冲淤演变特征及原因 总被引：4，自引：0，他引：4
利用黄河内蒙段1962-2000年间4期大断面观测资料,计算了各期河床冲淤和河槽形态指标。发现从1962-2000年间前20年、中间9年及后9年,内蒙河段河槽500m2过水面积下河底高程发生了降低-升高-再升高的过程;河槽漫滩过水面积经历了升高-降低-再降低的过程,2000年只有1982年的大约一半;滩地经历了持续淤积过程,平均抬升0.25m;河槽宽深比值经历了变化不显著-增加-减小的过程。分析结果表明:气候变化、引水、水库拦沙和重点产沙支流来沙变化在河床冲淤和河床形态调整中作用较大;水库对径流的年内调节对1982年后河槽淤积贡献较大;来水来沙变化下河流多要素自动调整是造成河槽形态变化过程复杂的原因。 相似文献
18.
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
19.
黄河宁蒙河段悬沙冲淤量时空变化及其影响因素 总被引：5，自引：0，他引：5
通过对黄河宁蒙河段6个水文站1952~2003年间的实测悬移质泥沙资料,运用输沙平衡方法,对划分的5个时段和5个区段的悬沙冲淤量进行了计算分析,探讨宁蒙河段悬沙冲淤量的时空变化规律。黄河上游无大型水库的1952~1959年间和水库建成坝下河道充分调整后的1994~2003年间,宁蒙河段强烈淤积,年均悬沙淤积量分别为0.9588亿t/a和0.9503亿t/a;而期间的三个时段,年均悬沙分别为净侵蚀0.6127亿t/a、微淤0.0161亿t/a和较强淤积0.7475亿t/a。年均悬沙淤积量在宁蒙河段为0.345亿t/a;在宁夏河段为0.076亿t/a,其中下沿河~青铜峡区段微淤,青铜峡~石嘴山区段冲淤平衡;在内蒙古河段总和为0.269亿t/a,石嘴山~巴彦高乐、巴彦高乐~三湖河口、三湖河口~头道拐三个区段分别为0.0084亿t/a、0.113亿t/a和0.147亿t/a,沿程增大。悬沙淤积量的时间变化主要受到区间支流来沙量变化和水库建设的双重影响,而空间变化主要受到青铜峡水库拦沙以及刘家峡、龙羊峡水库消减洪峰的影响。黄河宁蒙河段处于构造沉降区,淤积是总趋势,人类活动可以引起个别时段、区段发生侵蚀,但无法改变其沉积的总趋势。 相似文献