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1.
作为三峡水库诸多优化调度方式中的一种,洪水资源化利用对水库淤积的影响受到持续关注,开展针对场次洪水的相关研究有助于进一步深化对水库淤积科学问题的认识,有望为调度工作提供一定的技术支撑。通过2013年以来的历史水文资料分析与水沙运动数值模拟,探究了入库洪水的输沙过程以及洪水资源化利用对库区淤积与水库排沙的影响。结果表明:洪峰流量介于30000～55000 m3/s的中小洪水是近年三峡入库洪水的主要形式,随着入库洪峰流量的增加,洪水的地区组成逐渐趋向于金沙江下游、嘉陵江共同主导;常年回水区淤积、水库排沙是“消化”入库泥沙的两种主要途径,且以前者的作用为主;针对Ⅰ-3类入库洪水,坝前起调水位Z0的抬升或洪水资源化利用对水库淤积的影响主要在于造成了库区淤积的重分布,次要在于改变了水库的排沙作用,在Z0≤150 m条件下,洪水资源化利用对水库淤积的影响相对较小;针对典型洪水,当武隆洪峰流量Q’WL与入库洪峰流量Q’RK的比值小于1/5(即Q’WL/Q’RK<1... 相似文献
2.
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
3.
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
4.
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
5.
三峡水库是控制和开发长江的重要工程,具有巨大的防洪、发电、航运等综合效益.水库排沙比是反映水库拦截泥沙程度的重要指标.针对目前三峡水库排沙比计算没有考虑三峡水库区间来沙,结果偏大的问题,依据三峡水库区间水文站2003-2016年实测水文资料,采用水文学法估算了三峡水库区间月、年入库输沙量,分析了三峡水库排沙效果及主要影响因素.结果表明：1）三峡水库区间年均来沙量约1775×104 t,占总入库沙量的10.3%,近年来沙占比有所增大,其中2013-2016年来沙量占总入库沙量的26.9%;2）三峡水库年均排沙比为21.6%,其中围堰蓄水期为34.1%,初期蓄水期为17.0%,试验性蓄水期为15.4%;3）三峡水库采用"蓄清排浑"方式运行,主汛期7-9月的排沙比一般大于枯季,但2013年以后,出现了主汛期排沙比小于枯季的现象;4）入库细颗粒泥沙的排沙比大于粗颗粒泥沙,其中粒径d ≤ 0.062 mm的细颗粒泥沙排沙比为23.4%,0.062 mm0.125 mm的中粗沙排沙比分别为5.5%和11.1%;5）三峡水库排沙比汛期主要受V/Q影响,枯季主要受入库含沙量的影响;当V/Q约为170×104 s时,水库排沙效果最差;分别建立了汛期和枯季排沙比经验计算式.本文的研究成果可为三峡水库水沙优化调度等提供参考. 相似文献
6.
本文根据实测资料揭示三峡水库运行以来冬季下泄水温抬高5.32℃、夏初降低3.45℃、过程滞后30~43天,三峡水库冬季水温平均高于气温10℃,且随水库蓄水位和上游水库增加不断升高.长江是罕见的从高热河源流向低热潮湿地区的世界大河,干流三峡等大型水库流量大、库容大且基本没有温度分层,水库滞热、散热和下泄热量巨大,下游水温改变范围超过汉口.需要重视的两个宏观效应：一是超温大幅降低水库和下游水溶解氧（DO）,影响程度已与长江平均化学需氧量（COD）等污染同数量级,加上加速COD等耗氧,水温升高的污染危害更大;二是水库冬季巨大散热,11-1月库区平均散热强度241 W/m2、总热功率2.43亿kW,下泄潜在热量3.16亿kW、超过天然1.73亿kW,水库散发和下泄热量相当于全国平均用电功率.2030年上游水电按规划全面建成后,冬季上游水库群还将附加吸热2亿kW（年热量2万亿kWh）.DO是大坝对天然河流环境改变的重要方面,三峡支流库区现在连年水华、干流出现缺氧,水温升高进一步降低DO浓度和促进环境耗氧是当前库区和下游生态环境的主要问题之一.冬季干热河谷输出热水、2030年后更多梯级水库吸热并通过河流转移到三峡水库,巨大附加散热量对周边环境、水资源、土壤墒情和局部气候影响需要认真研究.建议在干热河谷梯级水库大规模布局水面光伏（PPV）.一方面遮挡短波辐射抑制下游三峡入库水温进一步升高,另一方面利用梯级水电巨大储能、调节优势与光伏资源,互补互助、集约和大规模开发西南可再生能源与电力调节资源.本文研究显示PPV电量巨大和结构优势明显,是改善我国电力能源结构和提升水电的发展方向,还可带动更多绿色发展. 相似文献
7.
支流作为水库综合效益发挥的重要组成部分,其河口泥沙大幅淤积会影响水库综合效益的发挥.选取多沙河流水库黄河小浪底库区畛水、石井两支流作为典型实例,在对1999-2015年汛后水库的来水来沙、水库调度、库区干支流淤积量与形态分析基础上,研究干支流淤积形态的变化,重点研究支流口门拦门沙坎抬升变化特征,结果表明：支流的分流及淤积与入库流量、含沙量及库区的淤积形态有关.入库流量越大,支流分流比小,支流淤积规模小;入库含沙量越大,支流分沙比越大,支流淤积规模越大. 相似文献
8.
三峡水库举世瞩目,是长江保护与治理的关键性枢纽工程,水库自2003年蓄水运行后库区水沙条件均发生了显著改变,对库区水生态环境产生了深远影响。本文系统综述了三峡水库蓄水运行后库区的水流动力特性和泥沙淤积特性,总结了蓄水后水库的新水沙运动情况;从水库蓄水运行后水质参数特征,营养物质、重金属和典型有毒有机污染物的赋存特征等方面,分析了三峡水库库区新水沙变化条件下的水环境响应特征;基于水库蓄水前后浮游植物、底栖动物等重点生物群落的现存量和群落特征变化规律,探索了三峡水库新水沙变化条件下库区的水生态响应特征;最后对未来三峡水库运行下的水生态环境效应研究提出展望,本文可为三峡水库水生态环境保护科学研究和管理提供新的认识和决策参考。 相似文献
9.
三峡及其上游干支流梯级水库建成运用后,大坝下游“清水下泄”引起了长江中下游河道发生长时间、长距离的冲刷。2001—2021年期间宜昌至长江口已累计冲刷了50.3亿m3,需厘清河道冲刷对河势、防洪、航运等方面产生影响。分析表明:三峡工程运用后,长江中下游河势总体稳定,弯道段出现切滩撇弯、汊道段出现塞支强干等现象;河道槽蓄量的持续增加,进一步增大了河道调蓄和行洪能力,但水流顶冲点的变化和近岸河床的冲刷下切,使得河道崩岸频发,并影响河势稳定和防洪安全;在河道冲刷、河势控制与航道工程综合作用下,长江中下游航道条件总体得到改善,但河道不均衡冲刷使得坝下游砂卵石河段出现“坡陡流急”,沙质河段出现洲滩散乱、航槽移位等现象,影响航道条件;同流量下枯水位呈下降态势,逢极枯年份影响长江中下游用水安全;江湖关系发生新变化,“三口”分流道由原淤积转为冲刷,两湖湖区水位不同程度的降低,枯水位出现时间有所提前,不利于湖区水资源和生态环境的安全与可持续发展;三峡工程实施枯水期补水调度和“压咸潮”调度以及长江口北支淤积减缓,对于遏制长江口咸潮入侵有利,入海泥沙显著减少引起长江口近岸河床冲刷,影响... 相似文献
10.
流域因素与人类活动对黄河下游河道输沙功能的影响 总被引：6，自引：0，他引：6
从泥沙收支平衡的概念出发定义了河道的输沙功能, 提出了河道输沙功能的定量指标, 研究了流域自然因子和人类活动对黄河下游河道输沙功能的影响. 这种影响可以用不同水沙来源区的降水量、进入黄河下游的大于0.05 mm粗泥沙占来沙量百分比、黄河上游水库对汛期清水基流的调节程度(以兰州站汛期径流量占全年百分比表示)、高含沙水流频率、流域内水土保持措施实施面积等来定量表达. 运用多元回归分析方法, 建立了黄河下游河道输沙功能指标与上述7个因子之间的多元回归方程. 表明不同水沙来源区降水量的减少对下游河道输沙功能的影响是不同的. 河口镇以上清水区和龙门至三门峡之间年降水量减少, 将导致下游河道输沙功能指标降低; 河口镇至龙门间降水减少, 将导致下游河道输沙功能指标增高. 来沙的组成强烈地影响下游河道输沙功能指标, 进入黄河下游的大于0.05 mm粗泥沙占来沙量百分比越大, 则河道输沙功能指标越低. 因此, 小浪底水库拦截粗泥沙、排出细泥沙, 将有利于提高下游河道输沙功能指标. 兰州站汛期径流量占全年百分比越低, 下游河道输沙功能指标越低, 说明黄河上游水库大量拦截汛期清水基流, 是下游河道输沙功能降低的原因之一. 相似文献
11.
Geomagnetism and Aeronomy - The evolution of the magnetic configuration in the solar corona is studied. The curvature of the K-corona helmets obtained from an analytical approximation of the... 相似文献
12.
D. M. Pechersky A. A. Lyubushin Z. V. Sharonova 《Izvestiya Physics of the Solid Earth》2010,46(7):613-623
The data on geomagnetic reversals are compared with the changes in the organic world and with the lower-mantle plumes. The
times of the formation of plumes and the times of their appearance on the Earth’s surface relate to the intervals characterized
by the different frequencies of geomagnetic reversals, i.e., there is no interrelation between the formation of plumes and
the frequency of the changes in the geomagnetic field polarity. At the same time, a certain synchronism is observed between
the frequency of the geomagnetic reversals and the boundaries of the biostratigraphic ages, i.e., the changes in the organic
world in the long-period range. A hypothesis is proposed, which explains the change in the sign of the geomagnetic field by
the combined effect of the irregular rotation of the internal core relative to the mantle and the changes in the slope angle
of the axis of the Earth’s rotation, which, in turn, results in synchronous events on the Earth’s surface: the rates of changes
in the organic world. 相似文献
13.
Yu. F. Moroz T. A. Moroz V. A. Loginov A. G. Nurmukhamedov D. A. Alekseev 《Izvestiya Physics of the Solid Earth》2016,52(1):29-44
The results of the magnetotelluric (MT) soundings before and after an earthquake are analyzed. The interpretation is based on the longitudinal and transverse MT curves (along and across the strike of the main tectonic elements, respectively). The MT curves are distorted by the ρ- and coast effect. The distortions due to the coast effect are estimated by the testing three-dimensional (3D) model. It is established that the coast effect distortion at the periods up to 1000 s is small and can be disregarded. The divergence of the longitudinal and transverse MT curves, which points to the presence of the deep faults, is thoroughly studied. The inversion of the MTsounding curves is carried out by the REBOCC program of the numerical two-dimensional modeling. This program implements the procedures of elimination of the ρ-effect and the joint inversion of the longitudinal and transverse MT sounding curves. The obtained geoelectrical cross sections provide an insight into the structure of electrical conductivity of the lithosphere before and after the earthquake. The more intense variations in the electric conductivity are observed in the zone of the deep faults. These variations are related to the changes in the porosity and saturation of the rocks by the highly mineralized fluids. 相似文献
14.
The idea of predicting earthquakes by continuously monitoring temporal variations in the tidal response of the medium was suggested by Beaumont and Berger in 1974. However, it became possible to implement the idea only recently. This possibility has arisen due to the deployment of Global Seismic Network (GSN), which collects the data on tidal tilts and gravity in the epicenters of strong earthquakes before and after the strongest events. In this paper, we present the results of model analytical and numerical calculations of the elastic displacements of the Earth??s surface caused by the earthquakes and their preparatory processes. The analytical calculations are limited to the model of a uniform elastic halfspace; the numerical calculations, in addition to this model, also cover the models with radially heterogeneous distributions of elastic moduli in the crust and in the upper mantle, which are determined by the PREM model. We describe the results of modeling temporal variations in the tidal response of the medium in the vicinity of the source of a catastrophic earthquake. The model of seismic source is specified by the length and the orientations of the fault plane and by the value of the discontinuity in the tangential component of the displacement vector on the opposite sides of the fault. The model is based on the GPS data on the horizontal and vertical displacements of the Earth??s surface. We suggest the method for determining temporal changes in the tidal response of the medium in the seismically active regions. This method improves the sensitivity and time resolution of the standard techniques of sliding-window analysis by more than an order of magnitude. The comparative analysis of temporal variations in the tidal response of the medium in the zones of the magnitude 9 earthquake in Japan (March 9, 2011) illustrates the described approach. 相似文献
15.
The idea of predicting earthquakes by continuously monitoring temporal variations in the tidal response of the medium was suggested by Beaumont and Berger in 1974. However, it became possible to implement the idea only recently. This possibility has arisen due to the deployment of Global Seismic Network (GSN), which collects the data on tidal tilts and gravity in the epicenters of strong earthquakes before and after the strongest events. In this paper, we present the results of model analytical and numerical calculations of the elastic displacements of the Earth’s surface caused by the earthquakes and their preparatory processes. The analytical calculations are limited to the model of a uniform elastic halfspace; the numerical calculations, in addition to this model, also cover the models with radially heterogeneous distributions of elastic moduli in the crust and in the upper mantle, which are determined by the PREM model. We describe the results of modeling temporal variations in the tidal response of the medium in the vicinity of the source of a catastrophic earthquake. The model of seismic source is specified by the length and the orientations of the fault plane and by the value of the discontinuity in the tangential component of the displacement vector on the opposite sides of the fault. The model is based on the GPS data on the horizontal and vertical displacements of the Earth’s surface. We suggest the method for determining temporal changes in the tidal response of the medium in the seismically active regions. This method improves the sensitivity and time resolution of the standard techniques of sliding-window analysis by more than an order of magnitude. The comparative analysis of temporal variations in the tidal response of the medium in the zones of the magnitude 9 earthquake in Japan (March 9, 2011) illustrates the described approach.
相似文献16.
为查明商丘市南部发育的2条断层——路河断层与商丘南断层的深部构造背景,在商丘市南部路河附近布设一条大地电磁测深测线,采用远参考数据观测与处理技术,获得地下电性结构,并对探测剖面深度5.5 km以上的电性剖面与地质剖面进行分析。结果表明,商丘南部的2条断层为倾向相对的正断层,南支规模较小,北支略大,均错断太古界,有向深部汇聚到主断裂的趋势,在太康隆起北部形成小型地堑。本研究结果可为商丘南部地震构造背景的相关研究提供参考。 相似文献
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Kapralova V. N. Chesnokova I. V. Makarycheva E. M. Sergeev D. O. 《Water Resources》2019,46(2):S81-S86
Water Resources - The dynamics of the talik zones, associated both with the internal cyclical nature of their development and with climate changes, leads to temporary differences in the volume of... 相似文献
19.
The developed dynamic model of the main geomagnetic field (MGF) includes the sources of three levels, which have existed and continuously changed during the 100-year period. The spatial-temporal dynamics of the secular variations in MGF has been considered based on this model. It has been indicated that, at different times, the formation of anomalies (located in similar regions) depended on the total dynamics of different combinations of sources, including a change in the parameters of the dipoles of the secondorder smallness. Anomalies generated by the dynamics of the dipoles of the third-order smallness do not evidently manifest themselves in the total secular variations but are responsible for the specific shapes of isodynamic lines. Based on the stability and continuity of the constructed model, the conclusion is made that long-living turbulent flows of different scales can exist in the liquid core. 相似文献
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Matthias Koschorreck Katrin Wendt-Potthoff Burkhard Scharf Hans H. Richnow 《Journal of Volcanology and Geothermal Research》2008
The biogeochemistry of methane in the sediments of Lake Caviahue was examined by geochemical analysis, microbial activity assays and isotopic analysis. The pH in the water column was 2.6 and increased up to a pH of 6 in the deeper sediment pore waters. The carbon isotope composition of CH4 was between − 65 and − 70‰ which is indicative for the biological origin of the methane. The enrichment factor ε increased from − 46‰ in the upper sediment column to more than − 80 in the deeper sediment section suggesting a transition from acetoclastic methanogenesis to CO2 reduction with depth. In the most acidic surface layer of the sediment (pH < 4) methanogenesis is inhibited as suggested by a linear CH4 concentration profile, activity assays and MPN analysis. The CH4 activity assays and the CH4 profile indicate that methanogenesis in the sediment of Lake Caviahue was active below 40 cm depth. At that depth the pH was above 4 and sulfate reduction was sulfate limited. Methane was diffusing with a flux of 0.9 mmol m− 2 d− 1 to the sediment surface where it was probably oxidized. Methanogenesis contributed little to the sediments carbon budget and had no significant impact on lake water quality. The high biomass content of the sediment, which was probably caused by the last eruption of Copahue Volcano, supported high rates of sulfate reduction which probably raised the pH and created favorable conditions for methanogens in deeper sediment layers. 相似文献