Marine renewable energy in China： Current status and perspectives

Based on a general review of marine renewable energy in China, an assessment of the development status and amount of various marine renewable energy resources, including tidal energy, tidal current energy, wave energy, ocean thermal energy, and salinity gradient energy in China＇s coastal seas, such as the Bohai Sea, the Yellow Sea, the East China Sea, and the South China Sea, is presented. We have found that these kinds of marine renewable energy resources will play an important role in meeting China＇s future energy needs. Additionally, considering the uneven distribution of China＇s marine renewable energy and the influences of its exploitation on the environment, we have suggested several sites with great potential for each kind of marine energy. Furthermore, perspectives on and challenges related with marine renewable energy in China are addressed.     

用沉积理论分析黄河的造陆过程

在第四纪沉积理论基础上,对第三纪沉积速率提出计算方法,并选择牛顿法解渤海湾盆地沉积速率,研究了中国大陆东部边缘渤海湾盆地的沉积过程,得出盆地区域内沉积速率的变化存在3个高峰值,其年龄分别为：距今0～2Ma、24．0～32．6Ma、38．0～42．0Ma,为认识古代环境与地质演变提供了科学的依据。论述了黄河的造陆过程,指出第四纪以来黄河对渤海湾盆地沉积贡献最大。约距今10万年,原海岸线大约以燕山、太行山、嵩山、大别山、黄山等为界,距今10万～1万年间,我国的东部海岸线向外推移1000余km。华北平原是以黄河为主和其他河流一起挟带泥沙沉积形成的,就是现在陆地海拔在0～200m高科之间的、占国土面积约12％的中国东部平原。     

THE STUDY OF THE YELLOW SEA WARM CURRENT AND ITS SEASONAL VARIABILITY

The Yellow Sea Warm Current (YSWC) penetrates northward along the Yellow Sea Trough, and brings warm and saline water towards the Bohai Sea. The YSWC becomes much less intrusive in summer and is limited mostly in the southern trough, contrasting with a deep winter penetration well into the trough. The seasonal variability of the YSWC has prompted a debate regarding which controls the YSWC and its seasonal variability. In this article, the annual mean and seasonal variability of the YSWC was examined by using a 3-D ocean model together with several experiments. The results show that in the annual mean the YSWC is a compensating current firstly for the southward Korea Coastal Current (KCC), which is mainly caused by the Kuroshio Current (KC). The local wind-stress forcing plays an important but secondary role. However, the local monsoonal forcing plays a prominent role in modulating the seasonal variability. A deep northwestward intrusion of the YSWC in winter, for instance, is mainly due to a robustly developed China Coastal Current (CCC) which draws water along the Yellow Sea trough to feed a southward flow all the way from the Bohai Sea to the Taiwan Strait.     

开阔海域越洋海啸波高计算的一种简化方法

该文研究了开阔海域中越洋海啸波高的简化计算方法。基于选取具有一系列断裂带长宽比的震源参数,采用Okada弹性变形理论生成初始海底变形,运用基于有限体积法的非线性浅水方程数值模型,模拟地震激发海啸在4 000 m水深的平底地形上的传播过程。通过监测布置在相对震源中心不同距离及方位角上测点的波面时间序列,研究海啸波高在不同距离及方位角上的分布规律,给出不同断裂带长宽比下越洋海啸传播过程中首波幅值的分布关系式;进一步分析了断裂带长宽比对模型参数的影响,得出了归一化的越洋海啸波高计算经验公式,并与日本2011年海啸实际记录进行对比,验证了该近似方法的有效性。     

Combined effects of coastal forest and sea embankment on reducing the washout region of houses in the Great East Japan tsunami

Coastal vegetation is widely recognized for its ability to reduce tsunami damage; however, coastal forests in large areas of the Tohoku and Kanto districts of Japan were destroyed by the Great East Japan tsunami on 11 March 2011. To elucidate the tsunami-mitigating effect of a coastal forest during a destructive tsunami, the combined effects of sea embankment and coastal forest were analyzed using post-tsunami survey data of the damage and a nonlinear long wave equation model that includes the breaking or washout condition of trees. The numerical simulations estimated that a 600-m-long coastal forest reduced the washout region of houses due to a 10-m-high tsunami at the coast by approximately 100 m, and the reduction achieved by a sea wall of approximately 5.4–6.4 m in height was approximately 560–1520 m. The height of a sea embankment or wall with sand dunes greatly affects the breaking condition of trees behind it by changing the tsunami flux overflowing the sea wall and the sand dune. For the combination of a sea embankment and a coastal forest during a destructive tsunami, the tsunami mitigation function of the coastal forest has an optimum value when the fluid force on the trees is strong but not strong enough to break the trees under the condition at which the tsunami overflows the sea embankment. At the investigated site, the effect of the coastal forest was larger than that of the sea embankment under optimal conditions. Thus, a coastal forest on a sand dune should be designed as a mitigation measure behind a sea embankment and optimally designed to protect the houses that are not protected from a tsunami by the sea embankment alone.     

SEASONAL VARIATIONS OF CIRCULATION AND SUSPENDED MATTER TRANSPORT IN THE YELLOW AND EAST CHINA SEAS

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Characteristics of wave amplitude and currents in South China Sea induced by a virtual extreme tsunami

This paper investigates the potential extreme tsunami hazards of the worst case scenario of the magnitude M_w=9.30 in South China Sea(SCS)as the Manila Trench is becoming one of the most hazardous tsunami source regions.Using nonlinear shallow water equations model,the time series of surface elevation,arrival time,spatial distributions of maximum wave amplitude and velocity distribution are presented.The characteristics of wave and currents are analyzed.The numerical results indicate that most of the energy of tsunami wave distributes in central and north part of SCS.The offshore regions around SCS will be influenced significantly by the tsunami currents generated by an earthquake in the Manila subduction zone.The maximum wave amplitude near Guangdong Province,Hainan Island,and Taiwan Island exceeds 4 m and velocities at the majority of measured locations near coast exceeds 2 m/s.Nested grid with high resolution is used to study the impacts of the tsunami on Hainan Island,Taiwan Island,and Lingding Bay.The regions with high hazard risk due to strong currents are identified.Finally,a fast tsunami warning method in SCS is developed and discussed,which can provide tsunami warning information in 5 min.     

南海海啸反问题预报模式

通过COMCOT海啸模型计算南海马尼拉海沟潜在震源区单元板块单位滑动产生的海啸波在区域内传播过程,将计算结果组成相应南海海啸波数据库.采用浮标监测数据与数据库结合通过最小二乘法构建南海海啸预报模式.以假想马尼拉海沟发生8.3级地震海啸为案例,应用预报模式对华南地区进行海啸预测,采用30 min和60 min监测数据分别反演计算,在三个近岸验证点的波高和正问题结果比较误差分别在25％和17％之内,到达时间及相位基本一致,预报的计算时间在2 min以内.     

基于局部拟合法的低能沙质海岸比尺设计

在波浪作用下的泥沙运动过程中,由于泥沙粒径的大小会影响到波浪边界层的紊动状态,以及泥沙沉降时绕流的紊动状态,进而影响其沉降和起动的规律,故波浪作用下的沙质海岸动床物理模型的比尺向来是一个复杂问题,其设计需要对各种因素进行衡量与取舍。而对于我国渤海、黄海沿岸常见的沙质海岸,其粒径范围决定了沉降时的绕流处于层流、紊流的过渡状态,沉降规律更为复杂,使其比尺设计更加困难。针对我国黄、渤海沿岸常见的低能沙质海岸波浪动床试验的泥沙比尺设计问题,探讨了适用于低能沙质海岸的比尺准则,剖析了比尺设计的难点,并提出了适用于一定泥沙粒径范围内比尺设计的局部拟合法。基于局部拟合法,针对低能沙质海岸剖面波浪动床试验,提出了相应的泥沙起动、沉速比尺关系式。     

海陆温差指数与我国华北地区降水的相关性分析

选取中国东部边缘海(渤海、黄海、东海)与我国华北地区20个站点的气温构建海陆温差序列,通过相关性分析的方法探讨三大海域海陆热力差异与华北地区降水的相关性,并利用海温或海温差定义的北极涛动(AOSST)和北太平洋涛动(NPOSSTD)分析其与华北地区降水的相关性,直接描述海气系统对我国华北地区气候的影响。结果表明:(1)华北地区降水对不同海域海陆温差的响应有所差异,其相关性非常显著,相关系数最高可达到0. 77。超前和滞后的相关系数明显高于同期相关系数,且超前和滞后的相关系数相差不大,并表现出相同的正负相关性,对应的月份形成12个月的周期变化。(2)涛动指数与三大海域海陆温差的相关性形成12个月的周期,但是SOI和Nino3. 4与三大海域海陆温差的相关系数很低,说明ENSO的发生通过其他的物理因素间接地影响我国的降水。(3) AOSST和NPOSSTD与华北地区降水的相关性与海陆温差相比没有提高,说明海洋上的大气环流与陆地的气候变化是相互影响的,其中通过中国邻近海域与陆地的热力差异可更准确地描述我国华北地区气候的变化。     

潮流对黄河入海泥沙在渤海中输运的贡献

基于ECOMSED模型研究分析单纯潮流作用下黄河入海泥沙在渤海中的输运特征。研究表明,渤海海域陆架坡度远小于内波特征参量,因此除黄河入海口附近以及其他近岸极浅海域之外,单纯潮流作用下渤海大部分海域的表层悬沙含量较低,但与实际水动力条件的空间分布格局基本一致。悬沙含量垂向分布特征明显,底边界层内因为较大的垂向湍流粘性系数,因此悬沙含量可以维持较高的水平,而底边界层之外悬沙含量迅速降低2～3个数量级;同时悬沙含量呈现出比较明显的潮周期(M2)变化特征。潮流作用下,绝大部分黄河入海泥沙沉积在黄河三角洲附近,只有少量悬沙可以发生长距离输送。黄河入海泥沙输运通量在口门外呈现一对涡状结构,成为水下三角洲南北两侧泥质沉积区形成的主要机制。     

条子泥二分水滩脊地貌动力与演变特征研究

通过对条子泥二分水滩脊的现场水文调查、滩面表层沉积物采样、断面高程测量等实测资料的分析整理,并结合近几十年来的遥感卫星图片资料,研究了条子泥二分水滩脊的地貌特征、沉积特征、水动力特征及其历史演变规律.结果表明:(1)二分水滩脊自西向东方向呈斜坡式下降,坡度约为0.64％,平均高程约为0.5m,脊部宽约1km,将条子泥沙洲分隔为南北两大地貌单元;二分水滩脊表层沉积物以砂质粉砂为主,自堤向海方向沉积物逐渐变粗.(2)测量期间落潮平均流速大于涨潮平均流速,流速自表层向下逐渐减小,涨、落潮最大流速均出现在表层;涨潮平均含沙量大于落潮平均含沙量,涨、落潮最大含沙量均出现在底层;涨潮单宽平均输沙量为1.30 kg,落潮为1.07 kg,表明沉积物来源丰富.(3)二分水滩脊位置并不固定,1974年以前二分水滩脊在蒋家沙-铁板沙一线近似呈直线条带状分布,此后逐渐北移,至2000年北移约15 kn至条子泥内缘区中部一竹根沙一线;2000年至今逐渐南移4.5 km.     

位山穿黄探洞应急加固工程大堤安全监测仪器安装埋设、观测及分析

介绍南水北调东线穿黄探洞应急加固工程大堤安全监测项目中测斜管、位移计、测压管等观测仪器的安装埋设、观测方法 ,并对所获得的观测资料进行初步的整理分析     

潮致地下水环流对黄河口外海含氮量的影响

近年来,渤海水质营养盐结构发生了显著变化,黄河口外海水质逐渐从高磷低氮向低磷高氮转变,特别是黄河口外无潮点海域水体无机氮含量较高。研究表明:由于无潮点海区沿海岸潮差分布差异比较明显,因此导致内陆一侧潜水层内地下水超高在空间分布上也存在显著差异,促使内陆地下水流从高潮差滨海区向低潮差滨海区运动,并促进内陆污染物迁移入海;靠近无潮点的海岸超高最小,成为地下水流的汇合入海处;随着近年来农村氮肥的大量使用,陆源污染有所加重,地下水中氮元素含量远高于地表水,在此类地下环流的长期作用下近岸海水中氮含量有所增高,由此导致局部海域水质逐渐由氮限制向磷限制方向演化。     

人类活动对典型三角洲演变的影响--Ⅰ长江和珠江三角洲

中国大多数河流三角洲发育,许多城市在靠近河口处发展起来并成为商业中心。日趋增大的人类活动的影响导致了新的问题,需要新的流域管理策略加以应对。长江、珠江、黄河和海河三角洲为我国河口三角洲的典型代表。本文以长江和珠江三角洲为例,讨论了三角洲的演变及相应的管理策略。长江携带大量的水、沙入东海,在河口处不断形成三角洲岛屿和浅滩,导致河道分汊。长江口实施的航道疏浚和填海造陆工程促进经济发展的同时,在一定程度上束窄和稳定了河口。珠江三角洲是由西江、北江、东江以及潭江、绥江、流溪河、增江等在珠江河口湾内堆积形成的复合三角洲。三角洲内河网密布,出海口门较多。促淤造陆、疏浚开挖排洪航运水道、人工采砂等改变了三角洲的演变。合理的调配水沙,控制无序采砂,有计划的围垦是珠江三角洲综合治理方略。     

玻璃纤维筋混凝土栅栏板在条子泥匡围工程中的应用

条子泥匡围工程处于东海前进潮波和南黄海旋转潮波辐聚区域,是江苏沿海辐射沙洲滩涂综合开发试验工程。为解决海水浪溅区的钢筋易腐蚀问题,该工程海堤护面采用玻璃纤维筋混凝土栅栏板代替传统钢筋混凝土栅栏板。通过对其设计、施工以及实施后效果进行分析,认为用其代替钢筋混凝土栅栏板可从根本上解决沿海地区的钢筋锈蚀问题,延长结构的使用年限。     

Weakening of the Asian Summer Monsoon and Its Impact on the Precipitation Pattern in China

The present paper provides a scientific assessment of the inter-decadal variability of the Asian summer monsoon and its significant effect on precipitation patterns in China. The paper consists of four parts. The first part shows the observed inter-decadal weakening of the Asian summer monsoon since the end of 1970s. The second part describes the impact of the weakening Asian summer monsoon on precipitation in China, which caused the major monsoon rainbelt to shift southward from North China to South China over about 30 years, with a 60–80 oscillation dominating. The third part projects the future change of the Asian summer monsoon in the warmer climate by using IPCC AR4 climate models. It has been found that major monsoon rainfall belts in East Asia will move northward in the 2040s, with summer precipitation in North China increasing considerably and stably. Finally, in the fourth part, the implication of the adaptation to the above climate change and related water management will be discussed including the water transport engineering project from the Yangtze River to the Yellow River and North China.     

1961—2016 年中国冰雹日数时空演变特征

采用 1961—2016 年 2 481 站的冰雹日数数据，利用多种统计方法分析了中国及七大地理分 区的冰雹日数时空分布特征和周期变化规律。结果表明: 1961—2016 年中国整体及其不同区域的冰 雹日数整体均呈减少趋势，且西藏(东南)地区明显高(低)于其他 6 个分区和全国平均水平。全国和 七大地理分区的年均冰雹日数在 5 年以下和 30 ～ 60 年尺度上的振荡周期相对显著，且大致都在 1990s 中期至 2000s 中期发生突变。中国冰雹事件多发区域比较稳定，且在分布上西部地区较多，东部地区 较少; 地表复杂地区较多，地表单一地区较少; 高原和山地较多，平原较少; 迎风坡较多，背风坡较 少。2000s 和 2010s 为全国冰雹日数偏多的年代，而 1960s 和 1990s 则偏少。1961—2016 年全国年均 冰雹日数呈增加趋势的地区分布较少，而呈减少趋势的地区主要集中在西藏、青海南部及东北部、四 川西部、新疆西北部、内蒙古中部及其交界的河北北部、内蒙古东北部、黑龙江中部和吉林东部地 区。全国年均冰雹日数波动特征从东南沿海向西北内陆呈现“两端高、中间低”的分布特征。波动较 大的地区主要分布在华东、华南、华中、重庆、四川东部、陕西南部、内蒙古西部、新疆东部及其交 界的甘肃地区、新疆南部及其交界西藏地区。     

海平面上升背景下辐射沙脊风暴潮增水研究

海平面上升将对沿海环境构成严重威胁,风暴潮灾害频发和加剧是其中的重要表现。相关研究揭示水深和潮波变化是引起风暴潮增水与海平面上升之间非线性关系的两大主要因素。在地形和潮波系统较为复杂的苏北辐射沙脊海域这种非线性关系尤为明显。总结了该海域潮波、风暴潮特征和海平面变化趋势,利用WRF模式和Delft 3D风暴潮模式相结合,建立了东中国海和南黄海二维天文潮-风暴潮耦合数学模型。分析研究了海平面上升以后,相同路径和强度的两种典型台风作用下,辐射沙脊海域风暴增水极值和高潮位变化。分析结果表明:海平面上升后,辐射沙脊海域增水作用普遍减弱,近岸较外海明显;而在辐射沙脊中、南部,海平面上升对天文潮高潮位的增强作用要强于对风暴增水的减弱作用。     

SEASONAL REVERSE OF SEA SURFACE SLOPE IN THE NORTHERN YELLOW SEA AND ITS DYNAMIC RELATION WITH MONSOON EFFECTS

Based on the monthly average sea level data from the tide gauge measurement (1999-2001), the seasonal variability of the sea level in the Northern and Middle Yellow Sea is studied to reveal that the sea surface height at all the tide gauges becomes higher in summer than that in winter. In addition, the sea surface height of the Northern Yellow Sea is higher than the one of the Middle Yellow Sea with a slope downward from the north to the south in summer, while it is lower with a reversed slope in winter. The seasonal reverse of the sea surface slope can be attributed to the monsoon effects i.e. the annual reverse of the monsoon direction and the annual variation of the monsoon rainfall. A set of equations are established in light of the dynamic principles to expound how the monsoon forcing and the sea surface slope generate a summer outflow and a winter inflow in the Yellow Sea.