利用滩坝砂体规模研究古风力的定量恢复^*     

王俊辉  姜在兴  鲜本忠  张春明  李国斌 《古地理学报》2021,23(5):937-950

古风力是一项重要的古气候指标,其定量恢复是一个难题。风作用于水体产生的波浪大小间接地反映了风力,能够为古风力的恢复提供思路。发育于破浪带和冲浪回流带的破浪沙坝、沿岸沙坝分别记录了破浪和冲浪过程,作者分别介绍利用古湖泊中发育的破浪沙坝和沿岸沙坝进行古波况和古风力恢复的原理和操作流程。(1)根据破浪沙坝的几何形态,可以将其厚度与破浪水深建立函数关系,而破浪水深又由破浪波高决定,因此破浪沙坝厚度可以恢复破浪波高,据此可以进一步根据波浪统计关系恢复有效波高、根据风浪关系恢复风力。此方法依托以下3个参数: 单期次的破浪沙坝厚度、破浪沙坝的基座坡角、古风程。(2)沿岸沙坝厚度近似记录了冲浪的极限高度,后者受控于有效波高,据此也可以恢复有效波高和风力。此方法依托以下5个参数: 单期次的沿岸沙坝厚度、古(平均)水深、古风程、古风向相对于岸线的入射角、组成沿岸沙坝的沉积物粒度。上述2种方法综合性较强,涉及古风向、古地形坡度、风程或盆地直径、古水深等参数的恢复,需要综合运用古地貌恢复、去压实校正、古岸线识别、古水深恢复等技术,并需要结合波浪理论。古湖泊滨岸带地层中保存有大量的滩坝沉积,利用其恢复古波况和古风况具有一定的应用前景,能够有助于更详细地重建沉积盆地的古地理背景。  相似文献   

基于镜像图的LRC和CRC偏差结合的人脸识别     

陈铭  周先春  周杰 《南京气象学院学报》2019,11(3):340-345

为了提高人脸识别率及更好地显示人脸特征,本文提出了一种基于镜像图的LRC和CRC偏差结合的人脸识别方法.该方法首先生成一种镜像人脸,再通过融合原始人脸和镜像人脸形成新的混合训练样本,最后利用LRC和CRC偏差结合进行人脸识别.新方法增加了训练样本的数目,克服了由于光照和姿态等外部因素带来的影响.实验结果表明,镜像图与LRC和CRC偏差结合的人脸识别方法提高了人脸识别的准确性.  相似文献   

"生态围垦"的前景及发展思路   总被引：3，自引：0，他引：3  

徐承祥 《海洋学研究》2006,24(Z1):1-5

浙江省人多地少,土地供需矛盾突出,而该省滩涂资源却相当丰富,科学开发利用这一资源是解决该省土地资源日趋减少的主要途径,其作用与意义愈加凸显.在加大围垦力度为浙江经济提供强大土地支撑的同时,必须树立"生态围垦"的发展理念和加强"生态围垦"的科学研究,营造优美和谐的生态环境,走可持续围垦之路,提出了实施"生态围垦"的5项措施,为"生态省"建设增添新的内容.  相似文献   

福建深沪湾地学旅游资源及其科学价值评价     

方世明  李江风  李丹阳 《海洋科学》2006,30(3):35-40

在对福建深沪湾地学旅游资源进行综合、系统的考察基础上,对福建深沪湾旅游资源进行了系统的分析与统计研究,并对其中的地质遗迹景观和类型进行系统分类,着重对海底古森林、古牡蛎滩、红土台地、古人类活动遗迹发现点和海蚀地貌等核心地质景观进行了阐述,并对其科学意义进行了尝试性探讨。  相似文献   

日照海岸带沙滩侵蚀现状及沉积物粒度特征分析     

种衍飞  郝义 《海洋地质前沿》2020,36(1):19-29

通过对日照市海岸带2个重点沙滩的现场调查和沉积物粒度计算,综合分析了沙滩的侵蚀现状和粒度参数特征。海滨国家森林公园沙滩北部和南部处于侵蚀状态,中部为缓慢淤积状态;万平口海水浴场沙滩北部、中部总体呈侵蚀趋势,南部为淤积状态。海滨国家森林公园沙滩的平均粒径总体要小于万平口海水浴场沙滩,这与两沙滩的坡度不同有关,平均粒径从滩肩到低潮线逐渐变小。海滨国家森林公园沙滩的分选性要好于万平口海水浴场沙滩,分选系数具有由陆向海、由北向南逐渐变小的趋势。沙滩的滩肩和滩面处频率曲线主要为双峰,峰态平坦,物质来源复杂,低潮线处频率曲线主要为单峰,峰态尖锐,物质来源单一。  相似文献   

The potential of Pléiades images with high angle of incidence for reconstructing the coastal cliff face in Normandy (France)     

《International Journal of Applied Earth Observation and Geoinformation》2020

To monitor chalk cliff face along the Normandy coast (NW France) which is prone to erosion, we tested the potential of cliff face 3D reconstruction using pairs of images with high angle of incidence at different dates from the agile Pléiades satellites. The verticality aspect of the cliff face brings difficulties in the 3D reconstruction process. Furthermore, the studied area is challenging mainly because the cliff face is north-oriented (shadow). Pléiades images were acquired over several days (multi-date stereoscopic method) with requested incidence angles until 40°. 3D reconstructions of the cliff face were compared using two software: ASP® and ERDAS IMAGINE®. Our results are twofold. Firstly, despite ASP® provides denser point clouds than ERDAS IMAGINE® (an average of 1.60 points/m² from 40° incidence angle stereoscopic pairs on the whole cliff face of Varengeville-sur-Mer against 0.77 points/m² respectively), ERDAS IMAGINE® provides more reliable point clouds than ASP® (precision assessment on the Varengeville-sur-Mer cliff face of 0.31 m ± 2.53 and 0.39 m ± 4.24 respectively), with a better spatial distribution over the cliff face and a better representation of the cliff face shape. Secondly, the quality of 3D reconstructions depends mostly on the amount of noise from raw images and on the shadow intensity on the cliff face (radiometric quality of images).  相似文献   

掘进工作面前方煤层底板高程动态预测的试验研究     

刘文明  程建远  刘再斌  张泽宇 《煤田地质与勘探》2021,49(1):257-262

快速掘进急需构建掘进前方高精度二维地质模型。以沁水煤田某矿区XY-S工作面为例,基于三维地震解释成果,利用巷道掘进过程中煤层底板高程实测信息,动态刷新三维地震平均速度场,更新掘进前方煤层底板高程,最后对掘进前方预测的精度进行统计分析。结果表明:通过不断利用掘进实测煤层底板高程,刷新平均速度场,更新掘进前方煤层底板地质剖面,掘进前方煤层底板剖面与实际揭露剖面之间误差逐渐越小,实测点前方25 m和50 m范围的煤层底板高程最小绝对误差可达0.2 m和0.45 m。若实测点数据密度大、分布均匀,预测精度将会进一步得到提高,可为快速掘进提供高精度煤层底板导航数据。   相似文献   

Numerical modeling of flow and morphology induced by a solitary wave on a sloping beach     

《Applied Ocean Research》2019

  相似文献   

An interpretation of wave refraction and its influence on foreshore sediment distribution     

Joevivek Vincent Jayaraj  Chandrasekar Nainarpandian  Jayangondaperumal Ramakrishnan  Thakur Vikram Chandr  Shree Purniema Krishnan 《海洋学报(英文版)》2019,38(5):151-160

To analyze the grain size and depositional environment of the foreshore sediments, a study was undertaken on wave refraction along the wide sandy beaches of central Tamil Nadu coast. The nearshore waves approach the coast at 45° during the northeast(NE) monsoon, at 135° during the southwest(SW) monsoon and at 90° during the non-monsoon or fair-weather period with a predominant wave period of 8 and 10 s. A computer based wave refraction pattern is constructed to evaluate the trajectories of shoreward propagating waves along the coast in different seasons. The convergent wave rays during NE monsoon, leads to high energy wave condition which conveys a continuous erosion at foreshore region while divergent and inept condition of rays during the SW and non-monsoon, leads to moderate and less energy waves that clearly demarcates the rebuilt beach sediments through littoral sediment transport. The role of wave refraction in foreshore deposits was understood by grain size and depositional environment analysis. The presence of fine grains with the mixed population, during the NE monsoon reveals that the high energy wave condition and sediments were derived from beach and river environment. Conversely, the presence of medium grains with uniform population, during SW and non-monsoon attested less turbulence and sediments were derived from prolong propagation of onshore-offshore wave process.These upshots are apparently correlated with the in situ beach condition. On the whole, from this study it is understood that beaches underwent erosion during the NE monsoon and restored its original condition during the SW and non-monsoon seasons that exposed the stability of the beach and nearshore condition.  相似文献   

工程养护海滩对"803"风暴潮的响应过程研究     

朱磊  杨燕雄  杨雯  房克照 《海洋通报》2019,38(1):102-14

研究养护海滩对风暴潮的响应过程在人工养滩工程设计与施工中具有重要意义。老龙头养护海滩在竣工半个月后遭遇“803”风暴潮,导致岸滩滩肩最大蚀退 6.5 m,沙坝坝顶最大下蚀 1.2 m。在现场测量的基础上,利用 XBeach 建立风暴潮过程 的老龙头海滩海床演变模型,研究结果表明： （1） XBeach 模拟结果与实际地形变化侵淤趋势一致,风暴潮期间人工沙坝均向岸移动,但模拟结果的侵蚀程度更大,海滩响应更加剧烈; （2） 强浪条件下人工沙坝的透射系数为 0.29~0.42,常浪条件下透射系数为 0.45~0.95,因而人工沙坝在大浪条件下掩护作用更佳; （3） 风暴潮期间人工沙坝附近破波显著,坝顶流速明显增大,最大可达 1.21 m/s,是无人工沙坝情况下的 2.3 倍,而在人工沙坝向岸侧,因波能提前耗散,流速减为 0.28 m/s,是无人工沙坝时的 0.4 倍,且没有产生离岸流。老龙头养护工程整体泥沙损失较少,易于恢复.  相似文献