共查询到18条相似文献，搜索用时 218 毫秒
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根据钱塘江河口治江围涂前和大规模治江围涂后现场实测的涌潮高度数据,对盐官以下河段大潮期涌潮高度的变化进行分析,结果表明,大规模治江围涂后的涌潮最高河段已由治江围涂前的新湾下移至大缺口段,并且大规模治江围涂后的涌潮最高值比治江围涂前增高了0.4 m,盐官河段增高0.1 m.盐官以上河段治江围涂后的涌潮高度变化,主要与径流对沙坎顶的冲淤密切相关,在其它条件相同时,治江围涂后的涌潮高度有所增大.这一结果与某些年份因涌潮增高,标准堤大量溢流等实例基本相符. 相似文献
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大江河中下游河段，预报河段上游站出现洪峰城作下注重站洪水过程承报时，洪峰流量预报可通过经验相关法，但洪水过程预报难度大，虽然马斯京根法可作洪水演算预报，但有一定局限性，一必须已知预报根据站入流过程，二必须已知演算公式的系数。 相似文献
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应用二维有限体积法、Osher格式及间断拟合法,计算了钱塘江河口涌潮产生、发展到消亡的全过程。该算法能保证水量和动量守恒,且能适应水深巨大变化和动边界。根据钱塘江涌潮的特点,可将其合理概化为一线潮。在网格尺寸较大情况下,计算的一线潮仍保持高分辨率,能准确满足水力学间断条件,且计算量小,可以在微机上实现。在对某实测半日小潮进行率定后,对随后的大潮进行了验证计算,涌潮的主要特征(如涌潮高度、移速、水位和流场等)与实测资料符合良好,证实了模型的合理性和模拟能力。 相似文献
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长江口北支的围垦使北支上、中段形成了河宽沿程变率较小的弯曲河槽,沿北支北岸的深槽水深条件得到改善,减弱了涌潮发生的条件,导致青龙港涌潮自2003年以来大为减弱。通过引进局部地形指数,建立了局部地形指数与青龙港平均涨率之间的良好相关关系。研究表明,青龙港平均涨率的年际变化与人类活动(围垦)在北支的进程以及青龙港附近的局部地形变化相应,并认为对于复式断面,采用全断面水力指标并不能很好地反映局部地形对涌潮的影响。由于长江口北支涌潮的近年变化将对长江南、北支分流点水域的河床演变产生重大影响,因此本研究对北支的航道整治和岸线开发利用具有现实意义。 相似文献
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合成流量法洪水预报方案有关问题的探讨吴成志，张世功，周玉华（山东省临沂水文局）１流域概况临沂水文站是沂河下游控制站，于流上游有葛沟水文站，支流上游有姜庄湖水位站，两站以上及两站到临沂区间的流域面积见表１，河流水系概况见图１。表互临沂站以上备部分流域面... 相似文献
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通过分析时间序列的卫片资料、4 m高的露头剖面的沉积学和元素地球化学特征, 研究钱塘江涌潮河段的滩槽冲淤变化规律、涌潮沉积特征和沉积层序.涌潮河段河道宽浅, 受径流与潮流相互作用强烈, 冲淤频繁且剧烈, 滩槽演替存在约20 a的周期, 与流域年代际洪、枯期转变有关.在滩槽叠置的垂向层序中, 底部为河槽、低潮滩相的厚层块状砂质沉积, 发育各种变形沉积构造, 为典型的涌潮沉积; 顶部为高潮滩相的潮汐韵律沉积, 发育典型的潮汐成因的双黏土层、大小潮周期; 二者之间的中潮滩相呈渐变过渡.C-M图和概率累计曲线可较好地区分涌潮沉积与潮成砂、泥质沉积.涌潮沉积层Si/Al、Zr/Al、Ti/Al等元素比值较高, 而潮汐韵律层Fe/Al、Mn/Al等元素比值较高, 这与它们的赋存方式和水动力分异有关.Si、Zr和Ti主要见于石英和重矿物中, 因此在强水动力沉积层中富集; 而Fe、Mn易被黏土矿物吸附, 在水动力较弱的中高潮滩富集. 相似文献
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黄河上游径流预报的灰色拓扑方法 总被引：5，自引：6，他引：5
以龙羊峡水库年平均入库流量预报为例，根据灰色系统理论的建模方法，利用龙羊峡水库入库水量代表站唐乃亥水文站的实测径流资料，建立了一个ＧＭ（１，１）拓扑预测模型，用于黄河上游径流的长期预报，并取得了较为满意的结果。 相似文献
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滑坡预报的多元回归分析方法 总被引：5，自引：0，他引：5
在回顾了滑坡预报的概念、类型及已有滑坡预报的几种主要模型的基础上，利用多元回归分析方法，根据最小二乘法原理，建立了非线性回归预报模型，提出滑坡破坏的时间为位移．时间曲线的拐点，此方法一般适合于临滑预报。结合实例，利用黄龙西村滑坡位移．时间监测资料，采用该模型进行滑坡时间预报，和其他滑坡预报模型预报的结果接近，说明该模型具有一定的合理性。 相似文献
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为了提高大江河洪水预报精度,结合本地大江河洪水特性,提出利用涨落洪规律建立洪水预报模型。该模型可以解决以下两个问题：一是大江河预报河段上游站不能通过降雨径流关系推求入流过程,而需要作下游站洪水过程预报问题;二是按马斯京根法进行河道流演算的没有预见期的问题。 相似文献
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Tidal bore is hydraulic jump during the process of tide flooding with the tide wave moving upstream. They are widely distributed in the estuary zone with high tidal range and funnel-shaped planeform. Tidal bore deposit study is important for further understanding about paleogeomorphology, paleoenvironment, paleoclimate of areas near the estuaries, and sandbody formed by tidal bore deposit could be potential oil and gas reservoir. Researches about tidal bore have been always concentrated on hydraulic characteristics of tidal bore and its influences on estuary environment and engineering, while the study on tidal bore deposit is rarely reported. One of the most important causes is the complex hydrodynamic conditions in the estuary zone. Deposits characteristics is complicated in this zone due to comprehensive effects of river flow, waves and tides. It is hard to affirm the preservation probability of tidal bore deposits, especially in the ancient rock record. In view of this, current status and forecast about tidal-bore deposit study were expounded in this study based on comprehensive summary and discussion about typical tidal bore deposit data and reports. Criteria for recognition of tidal-bore deposits were described in detail on the aspects of sedimentary structures, grain size distribution, and facies model. One of the most critical diagnostic marks of tidal bore was a special undulating erosion surface with a series of irregular and stepped excavations on it. This surface was formed by cyclic pressure loading induced by the passage of a tidal bore. In addition, the cross-bedding inclined upstream, soft sediment deformation structures and massive sandstone on the erosion surface were also important marks of a tidal bore deposit. Problems existing in current research were discussed and some suggestions were proposed. Various methods and technology should be used to perfect tidal bore facies model, and research on diagenesis and reservoir features of sandbody formed by tidal bore should be strengthened in the future. Sandbody formed by tidal bore of different types (breaking tidal bore and undular tidal bore) should be distinguished to deepen the understanding of their various hydrodynamic conditions and reservoir scale. Tidal bore is significant geological process in estuary zone, and deposits formed by it makes great influence on the geomorphology of this area, which should be paid more attention. 相似文献
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Natalie Bonneton Philippe BonnetonJean-Paul Parisot Aldo SottolichioGuillaume Detandt 《Comptes Rendus Geoscience》2012,344(10):508-515
In this article, we present a study on the tidal bore dynamics based on the analysis of the database acquired in 2011 during two simultaneous field campaigns in the Seine and Garonne Rivers. We have shown that in the Garonne River, contrary to the common view, undular tidal bore can form for a large majority of tides, even sometimes at neap tide when the river discharge is low. We have identified, from surface elevation measurements, low-steepness, low-frequency undular tidal bores which are not visually observable. Such low-frequency tidal bores have been also identified and characterised for the first time in the Seine River. In this river, the first undulation wave height can be higher than 1 m. We have shown that the secondary wave steepness strongly increases when the Froude number exceeds the critical value Fc. The large-steepness tidal bore regime corresponds to what is commonly termed in French mascaret. 相似文献
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磨刀门水道盐度混合层化机制 总被引：3，自引：0，他引：3
基于Simpson方法和磨刀门水道2009年枯季水文实测资料,选取上、下游两个站位的径流层化、潮汐混合、风致扰动3个影响河口水体分层的主要因素进行盐度混合的层化机制分析。研究表明:由于M1站位处上游,径流作用相对占优,分层不明显,只在涨潮急流时出现微弱的盐度分层;M2站则水体分层明显,小潮期间径流作用占主导,水体呈持续性分层,当由小潮转为中潮后,潮流作用增强,出现周期性分层现象,大潮以后,由于上游径流增加,潮流与径流作用相当,仍为周期性分层,但分层有所加强。层化的发育程度依赖径流致层化作用与潮汐、风致混合作用的博弈。 相似文献
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设计潮位过程线及其推求 总被引：2，自引：2，他引：0
针对现行推求设计潮位过程线方法中存在的不合理现象,在分析研究各潮汐要素之间的关系的基础上,提出根据高潮位(或低潮位)与潮差同频率控制放大的方法推求设计潮位过程线。结果表明,用该方法推算得到的设计潮位过程线比较符合实际,能较好地满足工程设计的防洪防潮标准,达到工程预期的效果。 相似文献
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海潮从长江口沿江上溯,可达内陆600km以上的潮区界,为世界大河所少见。中国古人就对这一现象有所感知,在一些文学著作与地方志中可找到长江潮区界及其变化的信息。在公元3世纪末、4世纪初,长江的潮波已越过柴桑(今江西九江);在公元9世纪早期,长江枯水期的潮区界已经退到九江的湓浦口;在13世纪最后的十几年,长江潮区界下移至皖赣交界的小孤山附近。从公元9世纪早期到13世纪晚期的470年间,潮区界下移了64 km,年均为0.136km/a。20世纪中叶以来的学者普遍认为,长江的潮区界又下移至安徽铜陵的大通镇。可见,长江干流在尚未被大型水利工程截断以前,长江潮区界持续向下游移动。在13世纪末至20世纪中叶的670年中,长江潮区界下移170km,年均为0.254km/a,速率几乎是前一时期的2倍。分析表明,潮区界下移速率和三角洲向海的淤长有关,还可能受气候变化的重要影响。对比发现,在长江干流大型水利工程开始蓄水的几年后、九江站流量约8440m3/s的特大枯水时期,潮汐引起的水位上涨影响可达九江附近、即1100多年前中唐时代的潮区界位置。 相似文献
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The tide can now propagate upstream for more than 600 km from the Changjiang River estuary to hinterland,which is rare in the world. In China,information and records reflecting tidal limit and its movement in the Changjiang River can be found from some ancient books,literary works and local chronicles. At the end of the 3rd and the beginning of the 4th century AD, the tide limit of the Changjiang River reached the upstream of Chaisang(now named Jiujiang in Jiangxi Province). At the early 9th century,the tide limit in the dry season retreated to the Penpukou in Jiujiang. In the last ten years of the 13th century,the tidal limit moved back to the Xiaogushan Mountain near the border between Anhui Province and Jiangxi Province. By the middle of the 20th century,the modern researchers generally agreed that the tidal limit retreated to Datong in Anhui Province. Before the main stream of the Changjiang River was cut off by large-scale water conservancy projects,the tide limit had retreated seaward continuously. From the 3rd decade of the 9th century to the last decade of the 13th century,the tide limit moved downstream 64 km during the 470 years,with an average annual rate of 0.136km/a. During the 670 years from the end of the 13th century to the middle of the 20th century,the tide limit had moved downstream 170 km,with an average annual rate of 0.254 km/a,almost twice as much as that of the previous period. We suggest the climate change accounted for the different retreat rate of the tidal limit between the two periods discussed. In addition,a recent study found that during the extremely dry periods,when the discharge of Jiujiang station was about 8440 m3/s,the tidal limit reached near Jiujiang. In the years when the water conservancy project on the main stream of the Changjiang River began to store water,the tide limit actually returned to the previous position of the middle Tang Dynasty,i.e. 1100 years ago. 相似文献