杭州湾北岸岸滩变化对海平面上升的响应——以龙泉—南竹港岸段为例

相对海平面上升引发的海岸潜在侵蚀是海岸带资源利用与规划的重点关注内容.基于杭州湾北岸龙泉—南竹港岸段实测断面资料,利用历史岸线后退和淹没法则计算法分析了该地区的海岸变化对海平面上升的响应.结果表明:近10 a来岸滩呈侵蚀后退趋势,年侵蚀速率为3.7～5.7 m/a,相对海平面上升对岸滩迁移后退的贡献为2％～6％;未来1...     

Consequences of short‐term changes in coastal processes: a case study

In 1997–98, unique critical beach erosion led to structural failure along the Penarth, South Wales, UK coastline and anthropogenic activities, such as the construction of the Cardiff Bay Barrage and offshore marine aggregate dredging, were suggested as causes. The time‐frame of significant erosion was between 1995 and 1997 and forcing agents (extreme sea level and wind direction) and shoreline indicators (mean beach level and MHW) were analysed in order to assess change. Water level analysis showed that although there was no significant difference between actual and predicted mean sea levels, extreme sea levels at that time were significantly higher (t = 3·305; d.f. = 8; p < 0·05). Three wind direction analyses (annual mean, mean annual maximum gust and mean annual maximum gust ≥28 kn) between 1995 and 1997 also showed significant differences (p < 0·05). All comprised more easterly components which meant they approached the beach from the sea. Furthermore, gusts ≥28 kn from the northeast quadrant, that is, 0° to 90° true, were significantly more frequent during these years (t = 3·674; d.f. = 8; p < 0·01). Justification of statistical significances was established and there was supporting evidence of unusual meteorological conditions at that time. Relationships showed correlation between forcing agents (extreme sea level and wind direction) and shoreline indicators (mean beach level and Mean High Water). Furthermore, regression analysis showed winds from the northeast quadrant resulted in steeper longshore gradients, as a consequence of beach material loss. Therefore, it was concluded that the critical erosion of Penarth beach between 1995 and 1997 was caused by increased wave attack from the northeast and southeast quadrants, generated by unique significant changes in wind direction and extreme sea levels. Copyright © 2008 John Wiley & Sons, Ltd.     

地层对比中层序地层学理论的运用——以滇东中下泥盆统为例

在滇东进行区域地质调查的过程中 ,详细研究了泥盆系中下统的层序地层 ,在不同地区 (武定盆地、昆明地区、曲靖盆地 )划分了若干个层序 (三级旋回 )、建立了各盆地的层序地层格架、估计了滨线上超三级旋回曲线。以此为基础 ,进行了盆地或地区间滨线上超旋回对比 ,发现其间具可比性。这种可比性对长期争议的滇东泥盆系中下统地层对比问题以及与之相关的盆地演化、构造作用、古地理轮廓、生物地层等问题的解决有很大的帮助。运用层序地层学理论进行盆地间地层对比的基本思路概括为 :　 1)对比的前提是对生物地层和构造作用进行详细而客观的研究 ;　 2 )对比的基础是各盆地建立层序地层格架 ,并估计出与沉积特征和范围尽可能协调的滨线上超旋回 ;　 3 )对比的关键标志是层序边界和凝缩段 ,此外 ,应该注意分布广泛的地质事件     

1996-2022年黄河三角洲行水河口岸线稳定性研究

黄河清八汊现行河口自改汊以来发生了巨大变化,监测其岸线变化,探讨其稳定程度对海岸带可持续发展以及海岸带韧性评估具有重要意义。本研究利用GPS、GIS、RS技术从1996—2022年黄河三角洲行水河口的220幅遥感影像中推断出年平均海岸线位置,同时根据行水河口摆动次数划分为5个阶段,并以此为基础对海岸线变迁及其稳定性进行定量分析。结果表明：行水河口岸线长期处于动态变化过程中,整体呈淤进状态,各岸段岸线时空变化特征不同,最大侵蚀（-73.89m/a）区出现在两丁坝之间,最大淤积（393.20m/a）区出现在河口区附近。研究区90%的岸线表现为较强淤积至严重淤积,稳定性指数由两丁坝之间（0.135）、2007年出汊前旧河口（0.068）、2007年出汊后新生河口（0.006）依次降低。入海水沙量、河口位置变迁以及沿岸输沙是影响岸线稳定性出现时空差异的主要原因。     

Fractal Analysis of the Complexity of United States Coastlines

Coastlines have long been used as a principal example of a natural feature that exhibits fractal structure. With the advent of large digitized databases, it has become possible to examine in detail large regions of coast and to examine differences in complexity, as measured by the fractal dimension, among regions. In this study, we have determined the fractal dimension of the Atlantic and Pacific coastlines of the conterminous United States. The traditional divider method was used in obtaining the fractal dimension of each coastline arc from the NOAA Medium-Resolution Shoreline Data Set. On average, the Atlantic coast has much higher fractal dimension than the Pacific coast. The results also indicate that the complexity of the Atlantic coast increases toward low latitudes. These results have implications for the interpretation of species distributions and diversity patterns along the coast and for the understanding of the dynamics of biotic recovery from mass extinctions.     

滇东寒武系层序地层学特征

介绍了对滇东寒武系进行层序地层学研究所采用的方法、层序的基本特征及取得的主要成果。确定有１０个层序，其时限为１～１０Ｍａ，其中下寒统武有６个，中、上寒武统各２个。此外还划分出次层序２７个、组合层序２个。此项研究工作对本区寒武系地层划分与对比、界线的确定具有重要意义：（１）沧浪铺阶生物地层的争论，是由于滇东存在两个Ⅰ型层序边界，乌龙箐段与红井哨段为假整合关系，故生物带发育不完整；（２）双龙潭组与西王庙组应为同时异相沉积体；（３）双龙潭组顶部时限，以ＳＢ２ｉ为标志，应与娄山关组底部边界对比，故可能上延至晚寒武世早期     

近30年来太湖流域湖泊岸线形态动态变化

湖泊的岸线特征是表征湖泊形态特征的一项重要内容．本文应用分形理论中的计盒维数,基于岸线长度与面积 关系的分形维数及岸线发育系数,对太湖流域主要湖泊的湖泊岸线变化进行了研究．结果表明,分形维数可以更好的对 湖泊岸线进行量化描述,太湖流域主要湖泊的岸线具有自相似性;近30年来,太湖流域湖泊的岸线曲折度降低,岸线长度 减少,岸线结构趋于单调．     

1973-2018年青海湖岸线动态变化

青海湖独特的地理位置使得其不仅对环湖周边区域气候起着天然调节器的作用,而且还拥有丰富的湖岸线资源,准确、及时地掌握青海湖岸线动态变化对保护沿湖生态环境有重要意义.因此本文基于1973-2018年Landsat MSS/TM/OLI遥感影像和1961-2017年实测水位资料,对青海湖岸线动态变化及对鸟类栖息地的影响进行研究,同时结合面积、水位及气象数据讨论了影响岸线变化的主要因素.研究表明：1）近45年来青海湖岸线发生变化最大的区域是东岸的沙岛,西岸的鸟岛、铁布卡湾及北岸沙柳河入口区域.尤其自2004年以来,鸟岛地区岸线后退距离最大（5.52 km）,鸟类栖息地扩张约97.94 km²,为鸟类提供了较好的栖息环境.（2）1973-2018年青海湖岸线长度以0.88 km/a的速率逐渐延长.1997年之前岸线长度呈较为平稳的上升趋势,1997-2004年呈波动下降趋势,2004年之后呈剧烈波动增加趋势,岸线曲折性也表现出相同的变化趋势.（3）总体上岸线长度和曲折性受水位和面积的影响并不显著,但在不同的水位情况下,二者对青海湖动态变化做出不同的响应.尤其当水位小于3193.3 m或面积小于4249.3 km²时,岸线曲折性会随着水位和面积变化呈现相同的变化趋势,而水位高于3193.3 m时,岸线曲折性一直在增加,且水位上升速率越大则曲折性年际变化越大.（4）1973-2004年间青海湖水位下降和土地沙漠化是造成湖岸线变化的直接成因,人类活动及草场退化加速了湖泊岸线的变迁.2004年之后,随着青海湖水位回升与面积扩张,岸线逐渐后退,尤其在2017-2018年岸线后退距离最大.     

大型湖库滨岸带蓝藻水华堆积风险评估——以巢湖为例

淡水湖库富营养化与蓝藻水华是全球性的突出水环境问题,尤其是滨岸带严重蓝藻水华堆积甚至造成了水体黑臭、威胁饮用水安全等严重危害,科学评估滨岸带蓝藻水华堆积风险、精准识别蓝藻水华易堆积区域是水环境管理与研究中亟待解决的关键科学问题.本研究以我国长江中下游的大型浅水富营养化湖泊巢湖为研究对象,依托流域水文与湖泊水动力模拟、遥...