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1.
lCOMPOSITIONOFTHE"92.8"FLOODThreerainstormsoccurredfrom7ththrough13,,,August,1992inShaanxiProvince,diStributingfromnorthtosouthinsequence.Therainfallareacoveredtheregionsofintensivesoilerosion,'wheretheaveragerateoferosionis10,000-15',000ton/kmZ'year.Fig.IshowsisohyetsofrainfallintensityinthecatchmentoftheMiddleYellowRiVerdepictingthedistributionoftherainstormsfrom7thto13,,,August,1992(thehydrologicalBureauYRCC,1992).ThecenterofthefirstrainstormwaslocatedattheYikezhaomengPrefec… 相似文献
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Boyuan Zhu Yao Yue Alistair G.L. Borthwick Wenjun Yu Enhang Liang Jinwu Tang Yuanfang Chai Yitian Li 《地球表面变化过程与地形》2020,45(11):2689-2705
In estuaries, the morphology of inland and offshore areas usually evolves synergistically. This study examines the decadal link between longitudinal changes in morphology of branching channels and movement of the offshore depo-center (where sediment deposition rate is maximum) of the Yangtze River estuary, under intense human interference. Integrated data analysis is provided on morphology, runoff discharge, and ebb partition ratio from 1950 to 2017. Channel-volume reductions and change rates between isobaths in branching channels reflect the impact of estuarine engineering projects. Ebb partition ratio and duration of discharge ≥ 60 000 m3 s-1 act as proxies for the water excavating force in branching channels and runoff intensity. It is found that deposition occurs in the lower/upper sub-reaches (or further downstream/upstream channels) of the inland north/south branching channels, and the offshore depo-center moves southward or southeastward, as runoff intensity grows; the reverse occurs as runoff intensity declines. This is because the horizontal circumfluence in the Yangtze estuary rotates clockwise as ebb partition ratios of the north/south branching channels increase/decrease for increasing runoff, and conversely rotates anticlockwise for decreasing runoff. Land reclamation activities, the Deepwater Channel Project, and the Qingcaosha Reservoir have impacted greatly on longitudinal changes of morphology in the North Branch and the South Passage and on ebb partition ratio variations in the North/South Channel and the North/South Passage. Dam-induced runoff flattening has enhanced deposition in the upper/lower sub-reaches of the north/south branching channels and caused northward movement of the offshore depo-center, except in areas affected by estuarine engineering projects. Dam-induced longitudinal evolution of branching channel morphology and offshore depo-center movement will likely persist in the future, given the ongoing construction of large cascade dams in the upper Yangtze and the completion of major projects in the Yangtze estuary. © 2020 John Wiley & Sons, Ltd. 相似文献
3.
ON THE SHRINKAGE OF RIVER CHANNEL 总被引：1，自引：0，他引：1
ＯＮＴＨＥＳＨＲＩＮＫＡＧＥＯＦＲＩＶＥＲＣＨＡＮＮＥＬＣＨＥＮＤｏｎｇ１,ＣＡＯＷｅｎｈｏｎｇ２ａｎｄＺＨＡＮＧＱｉｓｈｕｎ３ＡＢＳＴＲＡＣＴＡｌｏｎｇｗｉｔｈｔｈｅｒａｐｉｄｄｅｖｅｌｏｐｍｅｎｔｏｆｓｏｃｉａｌｅｃｏｎｏｍｙ,ｄｅｖｅｌｏｐｍｅ... 相似文献
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The annual changes of sediment deposition-scour on the riverbed in the Sanhuhekou-Toudaoguai Reach of the upper Yellow River during the years 1952-2010 were investigated based on runoff and sediment transport observations from the Sanhuhekou and Toudaoguai hydrological stations. Multiple influencing factors such as reservoir operations, tributary inflows, as well as runoff and sediment loads from the Shidakongdui area were analyzed. The results show that even though the sediment loads from the major sources, the Shidakongdui area as well as the upstream tributaries such as the Qingshui River and the Zuli River have reduced especially since the 2000 s as a result of enhanced water-soil conservation measures and improvement of vegetation cover, the study reach was still generally in a status of cumulative aggradation. This is mainly due to the joint operations of the Liujiaxia Reservoir and the Longyangxia Reservoir, which significantly reduced the annual runoff and sediment loads at the Sanhuhekou Crosssection. The reservoirs also remarkably altered the summer flood characteristics of the study reach, inducing the shape of the annual flow curve changing from a 'single-peak' into a 'doublepeak'. These alternations sharply decreased the sediment transport capacity of flooding in the summer flood season which yields more than 90% of the sediment loads, leading to an unbalanced relation between the water and sediment. In addition, the estimated incoming sediment coefficient of the Sanhuhekou Crosssection ranged from 0.003 to 0.014 kg s/m~6, of which 0.004 kg s/m~6 was suggested as a rough critical value to determine the scour or deposition status of the study reach. 相似文献
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I. INTRODUCTIONThe Yellow River is a heavily sediment--laden river. The sediment load of the Yellow River ranks the first in the world while its annual runoff is only of medium size. Toharness the river, it is necessary to build reservoirs for regulating runoff to meet the demands of economic development. Since the founding of PRC in 1949, I S4 large and medium--sized reservoirs have been constructed on the main stem and the tributaries with atotal storage capacity of 84.5 billion m3.… 相似文献
6.
《国际泥沙研究》2017,(4)
The Three Gorges Project(TGP) is a world known project to utilize and manage the water resources of the Yangtze River. The reservoir stores water at the end of the flood season, and replenishes downstream reaches with water in dry seasons. In addition to such benefits, the TGP has irreversibly changed the hydrological process and the river-lake relation of the middle and lower reaches. In this paper, a hydrodynamic model was established to quantify the impact of the TGP's operation on the water exchange between Dongting Lake and the Yangtze River during 2009-2013. The results indicated that:the operation of the TGP has considerably reduced the peak discharge and the flood volume of the main stream and the Dongting Lake area. The inflow volume from the Yangtze River to Dongting Lake via three outlets decreased by 1.9-3.5 billion m~3/yr, while the outflow volume from Dongting Lake to the Yangtze River at Chenglingji increased by 0.3-1.6 billion m~3 in September and 0.4-0.6 billion m~3 in October,respectively. This research provides valuable information for flood control, irrigation, and water allocation in the middle and lower reaches of the Yangtze River, and serves as a typical case for investigating the impact of other hydropower projects around the world. 相似文献
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1GENERALTraditionally,theLowerYellowRiverstartsatHuayuankouandrunsonaplainforabout800km,beforeemptyingintotheBohaiSea.Theriverisfedwithextremelyheavysedimentload(1.6billiontonsannuallyuptotheeighties)andrelativelysmallrunoff(46billionm3uptotheeighties)fromitsdrainagebasinupstream.Thisloadofsedimentispartlydepositedinthechannelresultinginaggradationorincreaseinthebedslope.TheremainderisdischargedtotheBobalSea.AsthetidesoftheBohaiSeaareweak,thedepositionintheareaaroundtherivermouthisusual… 相似文献
10.
TU Qiming Engineer Navigation Office of the Three Gorges Project Ministry of Communication 《国际泥沙研究》1991,(3)
Sedimentation problems in the access channels of the Gezhouba Navigation Locks at the Third Channel, which is of great importance for the navigation are discussed in this paper:1) the cause of deposition in the access channel, 2) effects of the deposit--reducing embankment and sediment sluices and 3) the relation between the sediment deposition at the Third Channel and the sediment discharge of the Yangtze River. Analyzing a four years' field data of sounding records with respect to the lock operation, it can be seen that the flood release through the navigation channel resulted in severe deposition, especially the sediment deposits induced by eddy current are difficult to be cleared off by flushing and jeopardize the working conditions of the lock operation. It is obvious that the flood release through the navigation channel should be minimized. In order to reduce the sediment deposits caused by eddy current attempts should be made to adjust the alignment of the boundaries and layout of the entrance of access channels. 相似文献
11.
JueyiSUI ChengLIU DaxianFANG JunWANG 《国际泥沙研究》2005,20(2):89-101
Based on long-term measurements at three gauging stations, Toudaoguai, Fugu and Hequ, and one meteorological station, this article discusses the features of discharge (Q) and sediment concentration (Cs) of a river reach of the Yellow River with a reservoir located in the Loess Plateau. The impacts of the local sub-watershed between Toudaoguai and Fugu gauging stations on sediment budget to the Yellow River have been analyzed. In addition, the deposition processes in the Tianqiao Reservoir have been investigated. Results show over 80% of the precipitation that falls in the local subwatershed is unable to contribute to the Yellow River runoff process. It is found that the annualmaximum sediment concentration is usually less than 30 kg/m^3 during flood seasons at Toudaoguai Gauging Station, but the sediment concentration varies dramatically at Fugu Gauging Station. About 35% of the sediment eroded in the sub-watersheds between Toudaoguai and Fugu gauging stationswas produced from the Huangfuchuan sub-watershed which has a drainage area accounting only for 10% of the drainage area between Toudaoguai and Fugu gauging stations. The Tianqiao Reservoir generally has deposition during the summer flood season, and scouring during the non-flood season.On average, over 85% of deposited sediment in the reservoir occurs in the 12 km long lower reservoir reach. The volume of annual deposition in the reservoir mainly depends on the volume of water from the local region between Hequ and Fugu gauging stations. 相似文献
12.
Changes in runoff and sediment load from major Chinese rivers to the Pacific Ocean over the period 1955-2010 总被引：1，自引：0，他引：1
Changes in runoff and sediment loads to the Pacific Ocean from 10 major Chinese rivers are presented in this paper To quantitatively assess trends in runoff and sediment loads, a parameter called the ＂Trend Ratio T＂ has been defined in this paper. To summarize total runoff and sediment load from these rivers, data from 17 gauging stations for the duration 1955 to 2010 has been standardized, and the missing data have been interpolated by different approaches according to specific conditions. Over the observed 56-year study period, there is a quite stable change in total runoff. Results show that the mean annual runoff flux entering the Pacific Ocean from these rivers is approximately 1,425 billion cubic meters. It is found that all northern rivers within semi-arid and transitional zones including the Songhua, Liaohe, Haihe, Yellow and Huaihe rivers present declining trends in water discharge. Annual runoff in all southern rivers within humid zones including the Yangtze, Qiantang, Minjiang, Pearl and Lancang rivers does not change much, except for the Qiantang River whose annual runoff slightly increases. The annual sediment loads of all rivers show significant declining trends; the exceptions are the Songhua and Lancang rivers whose annual sediment loads have increasing trends. However, the mean annual sediment flux carried into the Pacific Ocean decreased from 2,026 million tonnes to 499 million tonnes over the 56-year period. During this time there were 4 distinct decreasing phases. The decrease in annual sediment flux is due to the integrated effects of human activity and climate change. The reduction in sediment flux makes it easy for reservoir operation; however, the decrease in sediment flux also creates problems, such as channel erosion, river bank collapse and the retreat of the delta area. 相似文献
13.
Lagoonal tidal inlets are a typical morphology of the Central Coast of Vietnam. Recently, navigation channels in these inlets have become increasingly threatened by siltation. This study analyses the relations between sediment distribution and transport trends (using the technique of Sediment Trend Analysis-STA■) in the lagoonal system of the De Gi inlet and then proposes appropriate countermeasures against sand deposition in the navigation channel. The STA identified three types of transport trends in the De Gi inlet, namely dynamic equilibrium, net accretion, and net erosion. Processes associated with the tidal prism have resulted in trends of sediment transport and deposition across the flood and ebb tidal shoals, which maintain a present cross-sectional area of about 1000m^2. However, longshore sediment transport from north to south resulting from northeast waves cause additional sand deposition in the channel. In addition, the effects of refraction associated with a nearby headland and jetty also increase sedimentation. These processes provide the main reasons for sediment deposition in the De Gi inlet. Short term and regular dredging helps to maintain the navigation channel. A system comprised of three jetties (north, south, and weir) is necessary to ensure the longterm cross-sectional stability of the navigation channel. 相似文献
14.
Sediment load reduction in Chinese rivers 总被引：18，自引：9，他引：9
Cheng LIU Jueyi SUI and Zhao-Yin WANG Prof. Dr. International Research Training Center on Erosion Sedimentation Beijing China Associate Professor Environmental Engineering Program University of Northern British Columbia Prince George BC Canada Prof. Dr. Dept. of Hydraulic Engineering Tsinghua University Beijing China 《国际泥沙研究》2008,23(1):44-55
In this paper, the changes in the annual runoff and sediment transport have been assessed by using the long term observation data from 10 gauging stations on 10 large rivers across China from far north to far south. It is found that the annual sediment yield has generally had a decreasing trend in the past half century. According to the changes in annual runoff and the sediment yield per area, rivers in China can be classified into the following three groups： 1） rivers with decreasing annual sediment transport and stable runoff; 2） rivers with both decreasing annual sediment transport and runoff and 3） rivers with greatly reduced annual sediment transport and decreasing annual runoff. The results indicate that, in all southern rivers （to the south of the Huaihe River including the Huaihe River）, there has been little change in average annual runoff but a dramatic decrease in annual sediment transport. In the northern rivers, however, both the annual sediment yield and the runoff show significant evidence of reduction. To further investigate the recent changes in annual runoff and sediment transport, the short-term observation data from these 10 gauging stations in the recent 10 years have been assessed. Results show that both the annual sediment transport and the runoff have decreased＂ significantly in the northern rivers in the past 10 years. Using the Yellow River at the Lijin Station as an example, the average annual runoff for the last 10 years is only 1/3 of the long term average value and the average annual sediment yield of the last 10 years is only 1/4 of the long term average value. More unusually, in the Yongding River the annual sediment yield has approached zero and the runoff has decreased significantly. In addition, the impacts of human activities on the changes in both runoff and sediment transport have been discussed. 相似文献
15.
《Continental Shelf Research》2006,26(17-18):2281-2298
Since the 1960s a series of large reservoirs have been built in the upper and middle reaches of the Huanghe River. Changes caused by these reservoirs include a decrease in flood discharge and sediment load to the lower reaches and conversely, an increase of the silt concentration in the river water. This accumulation of silt in the river channel is a serious problem in the lower Huanghe River and has caused abnormal and distorted flow courses in the river bed. These effects include: shrinkage of the river channel, frequent dewatering (i.e., zero flow) in the river-mouth area, and hanging rivers (i.e., a river channel elevated above its floodplain). The zero-flow portion of the river has gradually extended upstream for nearly the entire 700 km of the lower reach. Utilization of the floodplains for agriculture and temporary villages has become a major problem. To counter these changes and situations, new measures, new methodology, and new thinking must be adapted incorporating results from the recent works on sediment transport and accumulation. Water conservancy works (dams, pumping stations, siphon-intakes, etc.) are typically used for adjustment of river water and sediment discharges and for irrigation and hydro-power generation. Recently, they are also being used to conduct tests using the reservoir water/sediment mix to flush out sediments deposited in the channel bed and transport the sediment to places where it is needed or into the Bohai Sea. Additionally, the future of the new deltaic sub-lobe in the Bohai Sea (developed in 1996) and the present estuary needs to be considered with respect to future development. 相似文献
16.
In-depth studies of water and sediment fluxes from rivers into the sea are very important for understanding the interactions between land and sea. This paper is concerned with identifying the changes in the time series of water and sediment fluxes from Feiyun River in Zhejiang Province, China. Inter- and intraannual variability in the water discharge and sediment load of the Feiyun River into the sea are analyzed using the observed data of runoff (1956–2008) and sediment (1957–2008) at Xuekou Station, which is in the main channel. The results show that there is a good peak–valley correlation between the water discharge and sediment load, and there are obvious seasonal variations, with a 65.7% water discharge and 89.2% sediment load during the flooding periods. Water discharge is mainly controlled by natural rainfall, but the construction of the upstream reservoirs in 1997 increased the discharge amount in the dry season and decreased the amount in the flooding season. Sediment loads were reduced after a huge flood in 1990 and construction of upstream reservoirs, while the latter also decreased the sediment load during the typhoon flooding period. Furthermore, the correlation between water discharge and sediment load is also affected by the flood and reservoir construction. There are some differences in the regression equations of sediment load and water discharge for 1957–1989, 1991–1996, and 1997–2008. 相似文献
17.
ONE D AND TWO D COMBINED MODEL FOR ESTUARY SEDIMENTATION 总被引：3，自引：0，他引：3
ZHANG Shiqi 《国际泥沙研究》1999,(1)
１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｆｌｕｖｉａｌｐｒｏｃｅｓｉｎａｎｅｓｔｕａｒｙｉｓｃｏｍｐｌｉｃａｔｅｄｕｎｄｅｒｔｈｅａｃｔｉｏｎｏｆｒｕｎｏｆ,ｔｉｄａｌｆｌｏｗ,ｗｉｎｄｉｎｄｕｃｅｄｃｕｒｅｎｔａｎｄｗａｖｅｅｔｃ．Ｅｓｐｅｃｉａｌｙ,... 相似文献
18.
泥沙问题是三峡工程建设与运行中的关键技术问题之一,只有妥善处理好泥沙问题,才能保证三峡工程长期有效使用,维持水库功能的全面发挥。本文首先结合实测水文、河道地形观测资料,对三峡水库运行近20年来的泥沙淤积特性及水库排沙比进行了较为全面的分析研究,并与已有研究成果进行了对比;其次,围绕防洪、航运以及坝前段的泥沙淤积等方面,进一步分析了水库淤积产生的影响。结果表明:三峡水库蓄水以来,在不考虑区间来沙的情况下,三峡水库共淤积泥沙20.484亿t,近似年均淤积1.102亿t,水库排沙比为23.6%,水库年均淤积量为原论证预测值的33%。其中,库区干流段累计淤积泥沙17.835亿m3(变动回水区冲刷0.694亿m3;常年回水区淤积18.529亿m3),淤积在水库防洪库容内的泥沙为1.648亿m3(干、支流分别淤积1.517亿m3和0.131亿m3),占水库防洪库容的0.74%,“十一五”攻关阶段研究得出的多年平均淤积量及排沙比较实测值均偏大,变动回水区冲淤则出现反向的... 相似文献
19.
1 INTRODUCTIONUnderstanding the flow characters in open channel or other water area, whether natufal water bodies(such as rivers and estuaries) or man-made strUctures (such as navigational channels, harbors), isimportant for addressing numerous hydraulic engineering problems. These include the selechons ofsuitable waste disposal sites, contndnant transport, sediment transport and other ecological problems.The major difficulty for solving these problems is that it often requires an optimal… 相似文献
20.
Rapid changes of sediment dynamic processes in Yalu River Estuary under anthropogenic impacts 总被引：2，自引：0，他引：2
The response of the Yalu River Estuary to human activities was investigated.Changes of sediment dynamics during the past 10 years were explored through hydrodynamic calculation,as well as heavy mineral... 相似文献