共查询到20条相似文献，搜索用时 46 毫秒
1.
1 INTRODUCTION Increasing attention is being given to sedimentation hazards downstream from reservoirs as dams built during the past century accumulate progressively greater volumes of sediment. The sediment storage both decreases reservoir capacity and operating efficiency of the dam, and creates a 搒ediment-shadow?downstream where sediment-starved flows commonly erode channel boundaries and create long-term channel instabilities. Numerous studies have documented downstream channel change… 相似文献
2.
Retrogressive erosion, a widespread phenomenon of sediment transport in reservoirs, often impacts on both the reservoir capacity and the sedimentation in the downstream river channel. Based on field data from the Sanmenxia Reservoir and the Lower Yellow River over the past decades, three courses of ret-rogressive erosion with distinctive features were analyzed. The results indicate that retrogressive erosion, especially caused by rapid reduction in the water level till the reservoir is empty, often results in the serious siltation of the lower Yellow River and threatens the safety of the flood control in the Lower Yellow River. Unreasonable operation of the reservoir and incoming hyperconcentrated floods accom-panied by retrogressive erosion also aggravate the siltation of the main channel of the river. However, a reasonable operation mode of the reservoir so named"storing the clear (low sediment concentration) water in the non–flood season, and sluicing the muddy(high sediment concentration) water in the flood season" was found, which might mitigate the deposition in both the reservoir and the Lower Yellow River. This operation mode provides important experience for the design and operation of large reser-voirs in other large rivers carrying huge amounts of sediment. 相似文献
3.
SHRINKAGE OF THE ESTUARINE CHANNELS OF THE HAIHE DRAINAGE SYSTEM AND ITS INFLUENCES ON FLOOD HAZARD 总被引：2，自引：0，他引：2
1INTRODUCTIONTheHaiheRiverBasinislocatedinNorthChinawithareaof262.6km2.Itisaquicklydevelopedareawithmanyimportantcitiesandindustrialhubs,includingBeding,Tianjin,Tangshan,Cangzhou,DezhouandHuanghua.Theareawatchedfastprogressesinurbanizationinthepastdecades,andhumanactivitieshaveresultedingreatinfluencesontheenvironment,riverhydrologyandsedimentbudget.Theareaisprojectedtobemoreprosperouswithmoreoilandgasfields,chemicalindustrybases,anddenserrailwaysandexpresshighwaysinthenextcent'Ury.T… 相似文献
4.
IMPACTS OF FLOOD EVENTS IN COARSE SEDIMENT-PRODUCING AREAS ON CHANNEL SILTATION AND FLUVIAL PROCESS OF THE LOWER YELLOW RIVER 总被引：1，自引：0，他引：1
Ou-yang ZHANG Xiufu FENG Jiong-xin XU 《国际泥沙研究》2007,22(2):142-149
The method of multiple regression is used to analyze the influences of flood events from the coarse sediment producing areas on the channel siltation and fluvial process of the lower Yellow River based on the flood events from 1950 to 1985. The results showed that the flood events from the coarse sediment producing areas carry larger amounts of sediment load and coarser particle sizes than from other source areas, which increases deposition in the lower river channel. And there exist good correlations between channel siltation of the lower reaches of the Yellow River and the coming water and sediment of flood events from the coarse sediment producing areas. Through these correlations, the amounts of sediment deposition in the lower river channel could be roughly estimated based on the runoff and sediment load of flood events from the coarse sediment producing areas. The sediment deposition caused the fluvial process. There exists a complex response of channel form change to the coming water and sediment load of flood events from the coarse sediment producing areas. When the sediment concentration is smaller than 200kg/m3, the ratio between wide-depth ratio after flood and wide-depth ratio before flood((B/h)a / (B/h)b) will increase with the increase of the maximum sediment concentration; when the sediment concentration is near 200kg/m3, (B/h)a / (B/h)b reaches the maximum value; and when the sediment concentration reaches the limits of hyperconcentrated flow, (B/h)a / (B/h)b will decrease with the increase of the maximum sediment concentration. Generally, flood events from the coarse sediment producing areas made channel form of the lower Yellow River deeper and narrower, but a large amount of sediment deposition simultaneously occurs. So, the impacts of flood events from the coarse sediment producing areas on the channel of the lower Yellow River are lessened. 相似文献
5.
[专稿]近年长江中下游径流节律变化、效应与修复对策 总被引：1，自引：0，他引：1
近十余年长江上游大量兴建大型水库,蓄水、调节和拦沙对中下游河川径流和泥沙产生了深刻影响.河川径流减少,径流季节提前,伏秋（特别是10月）流量显著降低、变差系数增大,97%严重干旱频率情景变成80%~85%.同时,宜昌和出海输沙量分别减少93%和70%,中下游河槽冲刷下降1~3 m,三峡蓄水后仅13年清水冲刷幅度和范围已超过三峡预期30年的冲刷上限,目前仍呈加速趋势.干流各站平均水位下降2~4 m,与此同时河道同流量洪水位反而升高.水库调节是水位降低的主要原因,河道冲刷更加剧水位降低,当前水位变化对防洪和生态都不利.汛后流量和干流水位提前降低使洞庭湖和鄱阳湖（两湖）提前干枯、松滋等"三口"入湖水量减少,伏秋高热季节两湖生态环境面貌发生了根本变化.汛后流量减少甚至显著增加长江大通十月流量小于15000 m3/s几率和上海长江水源受咸潮影响风险,10月咸潮入侵变成最严重时段必须引起高度重视.我们认为,径流和径流节律变化是当前长江生态环境最主要问题之一.建议以"水资源工程"重新定位上游大型工程、以"水资源优先"优化流域管理和切实回归既定三峡工程运行原则等统一调度和改善中下游水情;通过水库挖泥等措施修复长江物质通量,抑制中下游剧烈冲刷和稳定河流格局;加强中下游蓄滞洪区等防洪能力建设,为最大限度降低上游水库防洪和蓄水压力创造条件;主要通过改善上游水库调度维护两湖环境条件,"引清水入洞庭"和"增加供水设施建设"加强两湖适应能力.这是长江修复和保护重点. 相似文献
6.
《国际泥沙研究》2023,38(5):653-661
Studying the characteristics of runoff and sediment processes and revealing the sources of sediment provide key guidance for the scientific formulation of relevant soil erosion protection measures and water conservancy development plans. In the current study, the flow and sediment data of five hydrological stations on the main stream of the Fu River Basin (FRB) from 2007 to 2018 were selected to identify flood events, explore the variation of sediment transport along the FRB, and clarify the sediment sources. The results found that the Jiangyou–Fujiangqiao section is the main source of sediment in the FRB during the flood season. The runoff volume and sediment load during flood events in the Jiangyou–Fujiangqiao section accounted for 35% and 145% respectively of that of Xiaoheba station. These results combined with the change of the sediment load before and after the 2008 Wenchuan Earthquake (May 12) show that the sediment in this section mainly comes from the Fu River tributary–the Tongkou River watershed. The calculation results for the sediment carrying capacity of the Fu River show that the main stream was in a state of erosion in theory. However, according to the calculation results for the interval sediment yield during flood events, the sediment load at the Xiaoheba station was smaller than that at the Shehong station upstream. The analysis indicates that this was not because of sediment deposition in the river channel, but because of sand mining in the river channel and sediment interception by water conservancy projects. If heavy rainfall occurs in the FRB, the sediment accumulated upstream will move downstream with the resulting flood, and the sediment yield in the FRB may further increase. These research conclusions can provide reference information for improving the prediction and management ability of soil and water loss in the FRB and scientific regulation of the Three Gorges Reservoir. 相似文献
7.
The transfer of sediment through a highly regulated large fluvial system (lower Ebro River) was analysed during two consecutive floods by means of sediment sampling. Suspended sediment and bedload transport were measured upstream and downstream of large reservoirs. The dams substantially altered flood timing, particularly the peaks, which were advanced downstream from the dams for flood control purposes. The suspended sediment yield upstream from the dams was 1 700 000 tonnes, which represented nearly 99 per cent of the total solid yield. The mean concentrations were close to 0·5 g l?1. The sediment yield downstream from the dams was an order of magnitude lower (173 000 tonnes), showing a mean concentration of 0·05 g l?1. The dams captured up to 95 per cent of the fine sediment carried in suspension in the river channel, preventing it from reaching the lowermost reaches of the river and the delta plain. Total bedload transport upstream from the dams was estimated to be about 25 000 tonnes, only 1·5 per cent of the total load. The median bedload rate was 100 gms?1. Below the dams, the river carried 178 000 tonnes, around 51 per cent of the total load, at a mean rate of 250 g ms?1. The results of sediment transport upstream and downstream from the large dams illustrate the magnitude of the sediment deficit in the lower Ebro River. The river mobilized a total of 350 000 tonnes in the downstream reaches, which were not replaced by sediment from upstream. Therefore, sediment was necessarily entrained from the riverbed and channel banks, causing a mean incision of 33 mm over the 27 km long study reach, altogether a significant step towards the long‐term degradation of the lower Ebro River. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
8.
《水文科学杂志》2013,58(2):457-465
Abstract Periodicity of the runoff and the sediment load, and possible impacts from human activities and climatic changes, in the Yangtze River basin during 1963–2004 are discussed based on the monthly sediment and runoff data, and using the wavelet approach. Research results indicated that: (a) Sediment load changes are severely impacted by the different types of human activity (e.g. construction of water reservoirs, deforestation/afforestation); and the runoff variability is the direct result of climatic changes, e.g. the precipitation changes. (b) The impacts of human activity and climatic changes on the sediment load and runoff changes are greater in smaller river basins (e.g. the Jialingjiang River basin) than in larger river basins. The response of sediment load and runoff changes to the impacts of human activities and climatic changes are prompt and prominent in the Jialingjiang River basin relative to those in the mainstem of the Yangtze River basin. (c) Construction of the Three Gorges Dam has already had obvious impacts on the sediment transport process in the middle and lower Yangtze River basin, but shows no obvious influence on the runoff changes. Construction of the Three Gorges Dam will result in further re-adjustment of the scouring/filling process within the river channel in the middle and lower Yangtze River basin, and have corresponding effects on the altered sediment load because of the Dam's operation for the river channel, ecology, sustainable social economy and even the development of the Yangtze Delta. This will be of concern to local governments and policy makers. 相似文献
9.
Observation of the operation of the Sanmenxia Reservoir on the Yellow River has led to the conclusion that to preserve a certain effective storage volume for reservoirs built on heavily silt-laden rivers is feasible if the reservoir is operated according to the principle known as "storing the clear water and discharging the muddy flow". The relative stability of the bed elevation at the end of the backwater and the reservoir's erosion and deposition equilibrium depend on the compatibility of the pool level maintained in non-flood seasons with the conditions of flow and sediment load during flood seasons. Operating the reservoir to regulate the flood and sediment load during flood seasons can reduce the rate of aggradation in the Lower Yellow River. The basic condition for applying the operation mode of "storing the clear water and discharging the muddy flow" is that a sufficient amount of water should be used for discharging sediment during flood seasons. Under the condition of extremely low flow years, reservoir sedimentation cannot be avoided even if this operation mode is adopted. 相似文献
10.
2018年金沙江上游白格滑坡造成了近百年来最为严重的干流堵江事件,堰塞湖的形成和溃决给下游金沙江干流河道的水沙条件及梯级水电站运行造成影响.本文依据堰塞湖附近临时观测和金沙江干流河道控制性水文站的相关资料,研究堰塞体泄流对下游河道水沙输移的影响,同时结合梯级水库调度情况,计算了梯级水库的拦沙量.结果表明,堰塞湖溃决在金沙江中游形成了超历史的水沙过程,金沙江中游梯级电站开展应急调度后,堰塞湖溃决造成的特大洪水被削减为一般洪水.金沙江中游梯级梨园、阿海和金安桥电站累积拦截泥沙约1400万t,龙开口、鲁地拉和观音岩电站共计拦截泥沙约43万t,滑坡体产生的泥沙仍有约74%滞留在堰塞体附近.若滑坡体泥沙全部输移至金沙江中游梯级水库内,梨园电站的有效库容极有可能不满足水库所需调节库容的要求. 相似文献
11.
Wenxue LI Senior engineer Institute of Hydraulic Research Yellow River Conservancy Commission Zhengzhou China PU QI Senior engineer. Institute of Hydraulic Research Yellow River Conservancy Commission Zhengzhou China Zanying SUN E 《国际泥沙研究》1997,(3)
LINTRODUCTIONTheYellowforeriswellknownasaheavilysilt-caacingriverintheworld.Haaer-concentratedfloodsoftenoccurinitsmasterstemandaswellasthetriblltaries.ThecharacteristicsofdeformationandsedimellttranSportdifferfromreachtOreach.Duetohighsedimelltconcelltration,StrongfluvialactionandthenatUreofunSteadysedimenttranSPOrt,problemsandabnormalphenomenonareoflencreated.ThelaterbringinimpacttOnoodcontrolOfthelowerreach.Thus,itishelpfultoenhancetheunderstandingofthemotionlawsOfhaer-concentrat… 相似文献
12.
K.G.RANGARAJU U.C.KOTHYARI 《国际泥沙研究》2005,20(1):52-61
Withdrawal of water from a river into a canal involves the construction of a barrage or a dam across the river depending on whether the river is perennial or not. The design of the reservoir upstream of the dam and of the canal requires consideration of the sediment load carried by the river in case the river is sediment-laden. The basic equations concerning morphological changes in such rivers are discussed with particular reference to computation of reservoir sedimentation. The hydraulics of lined canals carrying wash load is examined from the point of view of limiting transport capacity and changes in frictional resistance. Lastly, the methods of design of sediment extraction devices like settling basins and vortex chambers are presented. 相似文献
13.
金沙江下游4个梯级水电站总装机容量相当于两座三峡水库,是“西电东送”中部地区的源头工程,工程效益发挥对经济社会发展意义重大。2012年以来,向家坝、溪洛渡、乌东德和白鹤滩电站等陆续蓄水运行,层层拦截金沙江的泥沙,2013—2020年向家坝出库年输沙量均值下降至152万t,减幅超过99%。大量泥沙淤积在梯级水库内,同时向家坝以下河道发生长距离冲刷。本文以自金沙江下游工程筹建以来的观测资料为基础,针对梯级水库的泥沙淤积和坝下游河道冲刷规律开展研究,结果表明:金沙江下游四个梯级电站自建成运行至2020年底,累计淤积泥沙约5.98亿m3,其中溪洛渡库区淤积量占比达92.5%,2013-2020年溪洛渡和向家坝水库排沙比分别为2.64%和22.2%,其水库泥沙主要淤积在常年回水区的干流河道内,以死库容内淤积为主,侵占有效库容的比例小于1.3%。金沙江下游库区干流河道的峡谷特征明显,淤积多表现为主河槽的平铺式淤高。溪洛渡和向家坝库区淤积的泥沙沿程分选特征明显,越靠近坝前,中数粒径减小、细颗粒泥沙沙量百分数增加,极细颗粒泥沙会在库区一定范围内大量沉积。向家坝下游河床普遍冲刷,但... 相似文献
14.
Optimization of the Sefid-Roud Dam desiltation process using a sophisticated one-dimensional numerical model 总被引：1，自引：0，他引：1
Ali KHOSRONEJAD 《国际泥沙研究》2009,24(2):189-200
Although water and soil conservation activities reduce reservoir sedimentation, it is inevitable that reservoirs fed by rivers transporting high amounts of sediment will experience sedimentation. The Ghezel-Ozan and Shah-Roud rivers, which flow to the Sefld-Roud reservoir dam, are both highly sediment-laden and transport significant amounts of sediment in both bed load and suspended load forms to the reservoir. Hence, it seems that the only practical way to remove the sediment from the reservoir is to flush it out using the Chasse method. In the present paper, field measurements of Chasse operation characteristics taken in previous years are presented, and a numerical model that simulates this process is introduced. After calibrating the model using field measured data, the calculated results （for reservoir pressure flushing and released sediment volume） of the numerical model were compared with other measured data for the same Chasse operation and the results agree well. Finally, using the numerical simulation results, the best approaches to ensure highly effective flushing while conserving reservoir water are presented （at least for the Sefid-Roud dam）. The operation of the bottom outlet gates, the shape of the output hydrograph, and the reservoir water level variation during flushing were optimized. In addition, the numerical model and related parameters, which need to be calibrated, are 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.
Yong-Nian XU Zhi-Yong LIANG Thao-Yin WANG China Institute of Water Resources Hydropower Research Beijing China. International Research Training Center on Erosion Sedimentation Beijing China. 《国际泥沙研究》2001,16(2)
1 wrsoooCTIoxThe Yeuow mver crtes a huge amoun of sedimcht and the noods often cause raPid and severeerosinn and dePOsihon. The channl bed of the YelOw mver often exPeriences degIadation in the mainchannel during fioods. In some cases vigorous erosion uP to l0 meters takes place in a shOrt Period oftiIn. Such phenomenon usually occurs in the ndddie reaChs of the Yelow mver and its tributaries suchas the Wdse mVer the Beiluohe mver etc. For examPle, th6 hyPenconcentraed nood in July l… 相似文献
17.
A 7-year sediment transport monitoring on the Upper Niger rivers was used to study the relationship between suspended sediment concentration and river discharge. During annual floods, these relationships show positive hysteresis. This paper presents the results of two models that estimate the time evolution of suspended sediment concentration using water discharge data only. The first model is based on a statistical approach using two relationships, one for the rising stage period of the flood and one for the recession period of the annual flood; the second model is a lumped conceptual one; it supposes that the sediment flux observed in the river comes from two different sources of sediment and that these two sources may be regarded as two different reservoirs. The erosion of the first reservoir represents hillslope erosion observed during the runoff season. Sediment supply from this ‘reservoir’ is limited in time because depletion occurs during the runoff season. The second reservoir is unlimited in time and quantity and its erosion represents contributions coming from bank erosion and mobilisation of deposits in the channel network.
Both of the models are compared with a simple rating curve based model. The model results show that the conceptual model has the highest efficiency to reproduce from weekly discharge only the time evolution of weekly suspended sediment concentrations, the time evolution of weekly sediment fluxes, and the global annual sediment yields. 相似文献
18.
ShixiongHU ZhaoyinWANG GangWANG XiaoyingLIU 《国际泥沙研究》2004,19(2):142-148
The Three Gorges Project is one of the largest hydro-projects in the world and has drawn many debates inside China and abroad. The major concern is that sediment load from the river basin may eventually fail the functions of the project for flood control and power generation. To reduce sedimentation in the reservoir, watershed management has been adopted. However, there is limited information regarding the effectiveness of various control measures such as terracing and afforestation on a watershed scale. The Jialing River, a main tributary of the Yangtze River, contributes approximately 25% of the total sediment load in the main river but only represents 8% of the whole basin area. There have been various land use patterns and extensive human activities for thousands of years in the Jialing River watershed. Based on analysis of the major factors affecting erosion in the Jialing River watershed, the main watershed management strategies (afforestation, farming and engineering practice) are illustrated, and their effects on the reduction of sediment and runoff are studied in detail. The sediment budget of the watershed shows that 1/3 of the sediment yield is trapped by the erosion control measures (afforestation and farming) on the slope, 1/3 is trapped by the reservoirs, ponds and dams within the watershed, and only about 1/3 is transported into the Yangtze River, which will affect the Three Gorges Project. 相似文献
19.
Xiaoya Tang Sichen Tong Guoxian Huang Guangxiang Xu Xinghua Li Kun Lei Shiming Yao 《国际泥沙研究》2021,36(2):177-189
Construction of large dams is attractive because of their great benefits in flood control,hydropower generation,water resources utilization,navigation improvement,etc.However,dam construction may bring some negative impacts on sediment transport and channel dynamics adjustments.Due to the effects of recent water and soil conservation projects,sediment retention in the newly constructed large upstream reservoirs,and other factors,the sedimentation in the Three Gorges Reservoir(TGR)is quite different from the amount previously predicted in the demonstration stage.Consequently,based on the measured data,characteristics of sedimentation and the related channel deformation in the TGR were analyzed.The results imply that sediment transport tended to be reduced after the Three Gorges Project(TGP).Sedimentation slowed dramatically after 2013 and indicated obvious seasonal characteristics.Due to the rising water level in the TGR in the flood season,the yearly sediment export ratio(Eratio)was prone to decrease.The water level near the dam site should be reasonably regulated according to the flow discharge to improve the sediment delivery capacity and reduce sedimentation in the TGR,and to try to avoid situations where the flood retention time is close to 444 h.The depositional belt was discontinuous in the TGR and was mainly distributed in the broad reaches,and only slight erosion or deposition occurred in the gorge reaches.Sedimentation in the broad and gorge reaches accounted for 93.8% and 6.2% of the total sedimentation,respectively.The estuarine reach located in the fluctuating backwater area experienced alternate erosion-deposition,with a slight accumulative deposition in the curved reach.Sedimentation mainly occurred in the perennial backwater area.The insight gained in this study can be conducive to directly understanding of large reservoir sedimentation and mechanism of channel adjustment in the reservoir region in the main channel of large river. 相似文献
20.
ON THE SHRINKAGE OF RIVER CHANNEL 总被引：1，自引：0，他引：1
ＯＮＴＨＥＳＨＲＩＮＫＡＧＥＯＦＲＩＶＥＲＣＨＡＮＮＥＬＣＨＥＮＤｏｎｇ１,ＣＡＯＷｅｎｈｏｎｇ２ａｎｄＺＨＡＮＧＱｉｓｈｕｎ３ＡＢＳＴＲＡＣＴＡｌｏｎｇｗｉｔｈｔｈｅｒａｐｉｄｄｅｖｅｌｏｐｍｅｎｔｏｆｓｏｃｉａｌｅｃｏｎｏｍｙ,ｄｅｖｅｌｏｐｍｅ... 相似文献