共查询到20条相似文献，搜索用时 31 毫秒
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近70年来荆江三口分流持续减少,为分析各历史阶段三口分流变化的驱动因素,根据1955—2021年干支流水文、地形实测资料开展研究,并基于控制变量法识别各驱动因素贡献比例。结果表明:三口分流阶段性减少,且集中在5—11月。长江上游降雨减少导致的干流来流偏枯以及下荆江裁弯、葛洲坝拦沙造成的干流河道冲刷和三口口门淤积对三口分流减少促进作用明显,调弦口堵口对三口分流影响不大,三峡水库蓄水后干流河道与三口口门同步冲刷,三口分流变化不大。长江上游汛期降雨减少明显,对5—11月三口分流减少影响较大,且三口分流主要发生于汛期干流中洪水位时,导致在下荆江裁弯期干流河床大幅下切条件下5—11月分流显著减少;葛洲坝调度、三峡水库初期调度和试验性蓄水调度也集中于5—11月,使得5—11月三口分流量分别减小0.4×108、12.5×108和38.6×108m3。调弦口堵口对三口分流的增大作用远小于降雨的减小作用,贡献比例为负值;下荆江裁弯对三口分流减少的贡献比例达85%;水库运用期降雨对三口分流减少的贡献最大,贡献比例大于50%,葛洲坝调度几乎不... 相似文献
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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
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三峡水库水环境与水生态研究的进展与展望 总被引：4，自引：0，他引：4
伴随着举世瞩目的三峡工程全面竣工,三峡水库于2010年正式进入年水位落差达30 m的正常运行阶段.水库湖沼学可为环境友好型大坝建设和水库可持续管理提供科学依据.本文在三峡成库8 a以来生态系统长期监测与研究的基础上,对三峡水库水环境现状进行了归纳和总结,分析了水环境动态的时空异质性、水库纵向分区与群落组成、垂向分布及藻类水华的成因和动态,并对三峡水库藻类水华预警与生态-水文调控机制展开了论述.最后,本文尝试给出以下两方面的展望:1)大型水库湖沼学观测研究应有长期的策略;2)近期研究应重点关注水华暴发水动力学机制的量化和水华预警模型及生态水力调度平台的耦合. 相似文献
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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
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Quantifying differences between reservoir inflows and dam site floods using frequency and risk analysis methods 总被引：1，自引：1，他引：0
Reservoirs are the most important constructions for water resources management and flood control. Great concern has been paid to the effects of reservoir on downstream area and the differences between inflows and dam site floods due to the changes of upstream flow generation and concentration conditions after reservoir’s impoundment. These differences result in inconsistency between inflow quantiles and the reservoir design criteria derived by dam site flood series, which can be a potential risk and must be quantificationally evaluated. In this study, flood frequency analysis (FFA) and flood control risk analysis (FCRA) methods are used with the long reservoir inflow series derived from a multiple inputs and single output model and a copula-based inflow estimation model. The results of FFA and FCRA are compared and the influences on reservoir flood management are also discussed. The Three Gorges Reservoir (TGR) in China is selected as a case study. Results show that the differences between the TGR inflow and dam site floods are significant which result in changes on its flood control risk rates. The mean values of TGR’s annual maximum inflow peak discharge and 3 days flood volume have increased 5.58 and 3.85% than the dam site ones, while declined by 1.82 and 1.72% for the annual maximum 7 and 15 days flood volumes. The flood control risk rates of middle and small flood events are increased while extreme flood events are declined. It is shown that the TGR can satisfy the flood control task under current hydrologic regime and the results can offer references for better management of the TGR. 相似文献
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洞庭湖三口洪峰流量和水位变异特性分析 总被引：1，自引：1，他引：0
近几十年来,受荆江裁弯、葛洲坝工程运用、三峡水库拦蓄调度、洞庭湖治理以及长江上游水土保持措施等因素的综合影响,洞庭湖三口(松滋口、太平口和藕池口)的水文情势发生了显著变化,给湖区防洪、水资源、水生态、水环境等造成一系列影响.为了深入认识三口洪水发生的复杂变化,本文采用水文变异诊断系统和Zivot-Andrews结构突变单位根检验方法,对三口各水文站点的年最大洪峰流量和年最高洪峰水位序列进行变异诊断,并对其变异特性和变异原因进行分析.结果表明,各站点洪峰流量序列的变异具有较好的一致性;受分流能力变化和上游来流变化的影响,三口各站点的洪峰流量多呈现方向向下的趋势变异;受到洪道冲刷、流量减小、顶托减弱、洪道上下游落差增大的影响,三口各站点洪峰水位在2004年均发生方向向下的跳跃变异. 相似文献
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Flood control of the Yangtze River is an important part of China’s national water security.In July 2020,due to continuous heavy rainfall,the water levels along the middle-lower reaches of the Yangtze River and major lakes constantly exceeded the warning levels,in which Taihu Lake exceeded its highest safety water level and some stations of Poyang Lake reached their highest water levels in its history.In August 2020,another huge flood occurred in the Minjiang River and the Jialing River in the upper Yangtze River,and some areas of Chongqing Municipality and other cities along the rivers were inundated,resulting in great pressure on flood control and high disaster losses.The 2020 Yangtze River flood has received extensive media coverage and raised concerns on the roles of the Three Gorges Dam and other large reservoirs in flood control.Here we analyze the changes in the pattern of the Yangtze River flood control by comparing the strategies to tackle the three heavy floods occurring in 1954,1998,and 2020.We propose that the overall strategy of the Yangtze River flood control in the new era should adhere to the principle of"Integration of storage and drainage over the entire Yangtze River Basin,with draining floods downstream as the first priority"by using both engineering and non-engineering measures.On the basis of embankments,the engineering measures should use the Three Gorges Dam and other large reservoirs as the major regulatory means,promote the construction of key flood detention areas,keep the floodways clear,and maintain the ecosystem services of wetlands and shoals.In terms of non-engineering measures,we should strengthen adaptive flood risk management under climate change,standardize the use of lands in flood detention areas,give space to floods,and promote the implementation of flood risk maps and flood insurance policies.The ultimate goal of this new flood control system is to enhance the adaptability to frequent floods and increase the resilience to extreme flood disasters. 相似文献
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河湖水文连通性强弱对于维系流域水资源安全、河湖生态系统稳定等方面具有重要意义.本文首先利用1960-2019年松滋口新江口与沙道观两站与干流枝城站实测水文资料以及河道典型横断面地形资料,采用Mann-Kendall法与趋势线法分析讨论枯水期松滋口分流变化的特征与诱因,然后,针对枯水期松滋口河道的分流问题提出河道治理方案.结果表明：松滋口枯水期的流量主要来自西支.在1960-2019年间,枯水期西支分流量呈现三峡大坝蓄水运行前后从下降趋势转变为显著上升趋势,而东支分流量在下荆江裁弯后至今基本处于断流状态,下荆江裁弯、葛洲坝运行及三峡大坝蓄水运行是其分流量变化的主要诱因.根据建立分流量与水位差（干流水位与河底高程）的回归关系,模拟出在松滋口西东支现有河道的基础上,河床高程分别下降1 m与2.5 m左右,其分流量可达到或接近1960s分流量水平,有助于缓解区域水资源与环境生态问题. 相似文献
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三峡水库蓄水引起库区水位抬升,水面面积显著增加,对区域水文循环过程产生了一定影响。为揭示三峡水库蓄水前后水面面积及蒸发损失变化规律,选取三峡库区坝前至寸滩区间作为研究区,利用Landsat影像数据提取1982—2021年水面面积,分区建立水位与面积关系曲线,进而推求库区逐日水面面积。在估计三峡库区水面面积的基础上,结合站点潜在蒸发资料推求水面蒸发损失量。研究结果表明:2010年三峡水库全面运行后,坝前至寸滩库区平均水面面积由蓄水前的372.96km2,增加到761.31km2,较蓄水前增加了1.04倍。同时,三峡水库的蓄泄调节改变了库区河段原有的水文节律,使得库区水面面积的季节性变化特征较蓄水前发生了显著变化。蓄水后,冬季水面面积最大,平均为843.81km2,较蓄水前增加了1.89倍;秋季、春季次之,水面面积分别为818.73和735.28km2,较蓄水前分别增加了97.17%和1.28倍;夏季水面面积最小,为653.03km2,较蓄水前仅增加了39.06%。水库全面运行后,... 相似文献
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三峡小江回水区透明度季节变化及其影响因子分析 总被引：1，自引：0，他引：1
三峡成库后其季节调蓄过程使该水域湖沼学特征具有独特性.根据三峡小江流域回水区段为期2年的定位跟踪观测,对透明度(SD)和主要环境指标的相互关系进行分析研究.研究期间,小江回水区透明度均值为170±7cm,各采样点透明度差异不明显且季节变化过程一致,自春末夏初开始降至最低水平,夏季汛期相对稳定,夏末入秋持续升高,冬季维持在较高状态,入春后下降.对透明度和主要环境指标的相关性分析发现,无机悬浮颗粒(PIM)是影响透明度的主要指标.透明度同PIM、Chl.a多元回归模型为:SD=(-89.389±8.101)·lg(PIM)+(-84.008±8.624)·lg(Chl.a)+(264.132±8.232).汛期低水位状态下(145-150m)小江回水区水动力条件趋于天然河道,河道输沙量增加使无机悬浮颗粒含量远高于藻类生物量而成为影响透明度的主要环境指标.在中水位(150-156m)和高水位(156m以上),虽然藻类进入非生长季节,但水位抬升和水体滞留时间的延长促使悬浮颗粒物大量沉淀,悬浮生长于表层水体的藻类成为影响透明度的主要环境指标,生物作用对透明度的影响明显. 相似文献
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Flood season segmentation, which partitions an entire flood season into multiple subseasons, constitutes a considerable water resources management task. Moreover, the risks associated with various schemes for flood season segmentation should be evaluated. Preliminary analysis in this study used the principal component based outlier detection (PCOut) algorithm to identify possible outlying observations to reduce the uncertainty involved in flood season segmentation. Then, a quantitative measurement, the seasonal exceedance probability (SEP), was proposed to evaluate various segmentation schemes. The SEP quantifies the risk that the maximum observation occurs outside the main flood season. Several findings were derived based on a case study of China’s Three Gorges Reservoir (TGR) and daily streamflow records (1882–2010). (1) The PCOut algorithm was found effective in identifying outliers, and the estimation uncertainty of the segmentation evaluation due to outliers decreased when the end date of main flood season (EDMFS) was postponed. (2) The proposed SEP measurement was shown capable of supporting quantitative evaluation of the segmentation schemes in the flood season. (3) The current flood segmentation scheme based on an EDMFS of September 10 is sufficiently safe for the TGR. The findings of this study could help in the proper operation of the TGR. 相似文献
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针对当前的水库提前蓄水调度研究尚未考虑碳减排问题,本文基于水库碳排放和有机碳埋藏因子法,构建了考虑碳减排的水库提前蓄水调度模型,采用基于熵权重的逼近理想解排序法(TOPSIS)对提前蓄水调度方案进行了多目标评价,以优选调度方案,在三峡水库开展了实例研究。研究结果表明:三峡水库从9月1日起蓄,于9月30日逐步蓄至167 m的调度方案最优,相较于原设计方案,在不增加防洪风险的前提下,多年平均发电量增加29.91亿kW·h(8.80%),弃水量减少26.03亿m3(27.51%),碳排放量减少69.26亿g(3.94%),有机碳埋藏量增加1.93亿g(1.28%),温室气体的CO2碳当量减少235.48亿g(3.85%),提前蓄水方案可显著提升三峡水库发电量、供水保障能力和减少碳排放量。本研究为水库提前蓄水的水碳协同调度提供了技术支撑。 相似文献
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Identifying flood seasonality is critical in hydrologic applications as well as water resources management. We develop an entropy-based method (EBM) for identifying flood seasonality and partitioning the entire flood season into multiple sub-seasons. The performance of the proposed EBM is evaluated using a Monte Carlo simulation test and compared with current methods. The Three Gorges Reservoir (TGR) basin in the Yangtze River is selected as a case study to test the applicability of the proposed method. Results of Monte Carlo simulation test demonstrate that the EBM performs better than the probability change-point method and the improved relative frequency method with less bias and higher efficiency. The case study results illustrate that the EBM can appropriately divide the entire flood season of the TGR into pre-flood season (from June 1st to June 20th), main-flood season (from June 21th to September 10th) and post-flood season (from September 11th to September 30th). The flood limited water levels (FLWL) in these three sub-seasons can then be derived, which are 150 m, 145 m and 149 m, respectively. Compared with conventional operation rule, the seasonal FLWL scheme can generate more hydropower (0.93 billion KWh) annually with a reliability of 99.86%. Therefore, it is meaningful to divide the entire flood season into three sub-seasons and apply seasonal FLWL for TGR operation. 相似文献
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ABSTRACTThe operation of the Three Gorges Reservoir (TGR) affects the evolution of the interactions between the Yangtze River and Dongting Lake in China and water diversions from the river, which are essential to water resources management in this large river–lake system. Due to the lack of up-to-date and detailed channel topographic/bathymetric data, a simplified flow model based on rating curves was developed to simulate discharges in the river system, and to further quantify and differentiate the contributions of river erosion and flow regulation of the TGR at a seasonal scale. The results indicate that the effect of channel alteration counteracts the effect of reservoir regulation in the high-flow periods. The impacts of TGR regulation on water diversions for both pre- and post-flood seasons were significant, but no obvious changes in the discharge diversion ratios were observed on an annual time scale. 相似文献
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Large wood distribution,mobility, and recruitment in an inter‐dam river reach: A comparison with geomorphic process on the Garrison Reach of the Missouri River pre and post the historical 2011 flood 
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下载免费PDF全文 Edward R. Schenk Adam J. Benthem Mark D. Dixon Melissa Mittelman Katherine J. Skalak Cliff R. Hupp Joel M. Galloway Rochelle A. Nustad 《地球表面变化过程与地形》2018,43(8):1677-1688
This study assessed the effect of the largest flood since dam regulation on geomorphic and large wood (LW) trends using LW distributions at three time periods on the 150 km long Garrison Reach of the Missouri River. In 2011, a flood exceeded 4390 m3/s for a two‐week period (705% above mean flow; 500 year flood). LW was measured using high resolution satellite imagery in summer 2010 and 2012. Ancillary data including forest character, vegetation cover, lateral bank retreat, and channel capacity. Lateral bank erosion removed approximately 7400 standing trees during the flood. Other mechanisms, that could account for the other two‐thirds of the measured in‐channel LW, include overland flow through floodplains and islands. LW transport was commonly near or over 100 km as indicated by longitudinal forest and bank loss and post‐flood LW distribution. LW concentrations shift at several locations along the river, both pre‐ and post‐flood, and correspond to geomorphic river regions created by the interaction of the Garrison Dam upstream and the Oahe Dam downstream. Areas near the upstream dam experienced proportionally higher rates of bank erosion and forest loss but in‐channel LW decreased, likely due to scouring. A large amount of LW moved during this flood, the chief anchoring mechanism was not bridges or narrow channel reaches but the channel complexity of the river delta created by the downstream reservoir. Areas near the downstream dam experienced bank accretion and large amounts of LW deposition. This study confirms the results of similar work in the Reach: despite a historic flood longitudinal LW and channel trends remain the same. Dam regulation has created a geomorphic and LW pattern that is largely uninterrupted by an unprecedented dam regulation era flood. River managers may require other tools than infrequent high intensity floods to restore geomorphic and LW patterns. Copyright © 2018 John Wiley & Sons, Ltd. 相似文献
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Zhenkuan Su Michelle Ho Zhenchun Hao Upmanu Lall Xun Sun Xi Chen Longzeng Yan 《水文研究》2020,34(3):705-717
The Three Gorges Dam is the world's largest capacity hydropower station located in the Hubei province along the Yangtze River in China, which began operations in 2003. The dam also functions to store and regulate the downstream releases of water in order to provide flood control and navigational support in addition to hydropower generation. Flow regulation is particularly important for alleviating the impacts of low- and high-flow events during the summer rainy season (June, July, and August). The impact of dam operations on summer flows is the focus of this work. Naturalized flows are modelled using a canonical correlation analysis and covariates of subbasin-scale precipitation resulting in good model skill with an average correlation of 0.92. The model is then used to estimate natural flows in the period after dam operation. A comparison between modelled and gauged streamflow post 2003 is made and the impact of the dam on downstream flow is assessed. Streamflow variability is found to be strongly related to rainfall variability. An analysis of regional streamflow variability across the Yangtze River Basin showed a mode of spatially negatively correlated variability between the upper and lower basin areas. The Three Gorges Dam likely mitigated the occurrence of high-flow events at Yichang station located near the dam. However, the high flow at the remaining stations in the lower reach is not noticeably alleviated due to the diminishing influence of the dam on distant downstream flows and the impact of the lakes downstream of the dam that act to attenuate flows. Three types of flow regime changes between naturalized and observed flows were defined and used to assess the changes in the occurrence of high- and low-flow events resulting from dam operations. 相似文献
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This paper summarizes the latest developments, future prospects, and proposed countermeasures of reservoir sedimentation and channel scour downstream of the Three Gorges Reservoir (TGR) on the Yangtze River in China. Three key results have been found. (1) The incoming sediment load to the TGR has been significantly lower than expected. (2) The accumulated volume of sediment deposition in the TGR is smaller than expected because the overall sediment delivery ratio is relatively low, and the deposition in the near-dam area of the TGR is still developing. (3) River bed scour in the river reaches downstream of the Gezhouba Dam is still occurring and channel scour has extended to reaches as far downstream as the Hukou reach. Significantly, sedimentation of the TGR is less problematic than expected since the start of operation of the TGR on the one hand; on the other hand, the possible increases in sediment risks from dependence on upstream sediment control, deposition in the reservoir, and scour along middle Yangtze River should be paid more attention. (1) Sediment trapped by dams built along the upper Yangtze River and billion tons of loose materials on unstable slopes produced by the Wenchuan Earthquake could be new sediment sources for the upper Yangtze River. More seriously, possible release of this sediment into the upper Yangtze River due to new earthquakes or extreme climate events could overwhelm the river system, and produce catastrophic consequences. (2) Increasing sediment deposition in the TGR is harmful to the safety and efficiency of project operation and navigation. (3) The drastic scour along the middle Yangtze River has intensified the down-cutting of the riverbed and erosion of revetment, it has already led to increasing risk to flood control structures and ecological safety. It is suggested to continue the Field Observation Program, to initiate research programs and to focus on risks of sedimentation. 相似文献
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Stochastic modelling of a diffusive wave for flood propagation using the random walk particle tracking method in a hypothetical city 下载免费PDF全文
下载免费PDF全文 Deterministic numerical schemes have been widely used for the solution of the diffusive wave (DW) equation, however, these schemes are computationally costly and suffer instability issues. This paper presents a stochastic random walk particle tracking (RWPT) method to solve such an equation for a dam‐break flow problem. Three different wave duration scenarios are presented for simulations of the DW for flood flows in a hypothetical city. The hypothetical city is represented by a domain of size 2,000 m by 500 m in x and y directions, respectively. The domain is divided into 25 m by 25 m cells. A dam is located at the upstream of the hypothetical city. Each scenario has a distinct propagation pattern after the dam is breached. Analysed and presented are 18 different simulations, which are composed of three different building configurations, two different bed slopes, and three different shapes of hydrographs. In this method, the flood volume is divided into a large number of particles where each particle carries a fixed amount of the flood volume. These particles undergo convective and diffusive movements, and their superposition represents propagation of the DW in the flow domain. The solution algorithm of the RWPT‐based equations is used to compute flood inundation depths in the hypothetical city. Comparison is drawn among the simulated results from three different shapes of the inflow hydrographs. The proposed stochastic method has two major advantages over traditional deterministic schemes: (a) greater efficiency, thus lesser computational costs, and (b) no instability issues. 相似文献