Numerical investigation of the effect of seasonal variations of depthof-closure on shoreline evolution     

Xuan Tinh Nguyen  Minh Thanh Tran  Hitoshi Tanaka  Trung Viet Nguyen  Yuta Mitobe  Cong Dien Duong 《国际泥沙研究》2021,36(1):1-16

The current study presents the effects of seasonal variations in the depth-of-closure(Dc)on shoreline evolution using a numerical,one-line shoreline model.Beach erosion of the southern beach of the Nha Trang Coast,which is located in south central of Vietnam,is selected as the study area.This study area is immensely influenced by the tropical monsoon climate that has a clear pattern of large waves in the northeast monsoon season and calm waves in the non-monsoon season.The analysis of the long-term measured shoreline variations from a video-camera system has found a strong correlation of these variations to the monsoon-dominated wave characteristics in the Nha Trang Bay.Therefore,a new approach for determining the depth-of-closure with consideration of the seasonal wave climate changes is purposed in the current study.By implementing this new approach into a numerical,one-line shoreline model,it is found that the seasonal variations of Dc appear to better describe the periodical shoreline evolution due to the monsoon-dominated wave characteristics for the Nha Trang Coast.Such important findings are considered to commonly apply for monsoon-dominated coastal regions in general.These findings are useful information not only for scientific readers but also for the coastal authorities and managers in order to make better countermeasure plans against this kind of erosion mechanism in the future.  相似文献   

The effect of temporal wave averaging on the performance of an empirical shoreline evolution model     

M.A. Davidson  I.L. Turner  R.T. Guza 《Coastal Engineering》2011

The effect of using time-averaged wave statistics in a simple empirical model for shoreline change is investigated. The model was first calibrated with a six-year time series of hourly wave conditions and weekly shoreline position at the Gold Coast, Australia. The model was then recalibrated with the hourly waves averaged over intervals up to 1 year. With wave averaging up to 2 days, model performance was approximately constant (squared correlation r² ~ 0.61–0.62), with only small changes in the values of empirical model parameters (e.g. the beach response coefficient c varied by less than 4%). With between 2 and 40 day averaging, individual storms are not resolved; model skill decreased only modestly (r² ~ 0.55), but c varied erratically by up to 40% of the original value. That is, optimal model coefficients depend on wave averaging, an undesirable result. With increased averaging (> 40 days) seasonal variability in the wave field is not resolved well and model skill declined markedly. Thus, temporal averaging of wave conditions increases numerical efficiency, but over-averaging degrades model performance and distorts best-fit values of model free parameters.  相似文献   

SWASH: An operational public domain code for simulating wave fields and rapidly varied flows in coastal waters   总被引：1，自引：0，他引：1  

Marcel Zijlema  Guus StellingPieter Smit 《Coastal Engineering》2011

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Late Devensian and Holocene relative sea‐level changes on the Isle of Skye,Scotland, UK     

Katherine A. Selby  David E. Smith 《第四纪科学杂志》2007,22(2):119-139

Detailed litho‐ and biostratigraphical analyses from three coastal sites in contrasting coastal settings on the Isle of Skye, Scotland, UK, reveal evidence for several changes in relative sea level during the Late Devensian and Holocene. At the start of the record, relative sea level in the area was high at ca. 12 500 ¹⁴C (ca. 14 800 cal.) yr BP but then fell, reaching a low point during the Younger Dryas, at ca. 11 000–10 000 ¹⁴C (ca. 13 000–11 600 cal.) yr BP, when a rock platform, correlated with the Main Rock Platform, was formed. In the early–middle Holocene, relative sea level was rising by ca. 8000 ¹⁴C (ca. 8800 cal.) yr BP and in northeast Skye a lagoonal surface, correlated with the Main Postglacial Shoreline, was formed at ca. 6600 ¹⁴C (ca. 7500 cal.) yr BP. By the late Holocene, relative sea level was again falling, but a rise, registered at at least two sites, began probably before ca. 4000 ¹⁴C (ca. 4500 cal.) yr BP, and a second lagoonal surface in northeast Skye, correlated with the Blairdrummond Shoreline, was formed, although by ca. 3000 ¹⁴C (ca. 3200 cal.) yr BP relative sea level in the area had resumed its downward trend. The pattern of relative sea‐level changes disclosed is compared with evidence elsewhere in Scotland. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

The development of the SCAT process for the assessment of oiled shorelines     

Owens EH  Sergy GA 《Marine pollution bulletin》2003,47(9-12):415-422

The Shoreline Cleanup Assessment Team (SCAT) process is a tool to assess oiled shorelines and is now an integral component of spill response operations. The key element of a SCAT survey is a systematic documentation using standard terms and definitions of the shoreline in the areas affected by an oil spill. SCAT programs were initially established to provide objective and accurate shoreline oiling information directly to cleanup operations. The role of the SCAT program has since expanded and the information generated by the field teams is used now by planners and decision-makers and to develop shoreline treatment recommendations, to select appropriate treatment techniques, and to establish the level or degree of treatment that is appropriate. This latter point is an integral part of establishing shoreline treatment criteria or standards and treatment end points.  相似文献   

Evaluation of various satellite sensors for waterline extraction in a coral reef environment: Majuro Atoll, Marshall Islands   总被引：4，自引：0，他引：4  

Hiroya Yamano  Hiroto Shimazaki  Tsuneo Matsunaga  Albon Ishoda  Caleb McClennen  Hiromune Yokoki  Kazuhiko Fujita  Yoko Osawa  Hajime Kayanne 《Geomorphology》2006,82(3-4):398-411

The ability of five satellite sensor bands (IKONOS band 4, Terra ASTER bands 3 and 4, and Landsat ETM+ bands 4 and 5) was examined to extract the waterline at coral reef coasts (Majuro Atoll, Marshall Islands) using different wavelength regions (near infrared [NIR] and shortwave infrared [SWIR]) and different spatial resolutions (4, 15, and 30 m). After performing georeferencing and normalization of the images, density slicing was used to extract the waterline. Comparisons of extracted waterline positions with ground-level data for eight transects and global positioning system (GPS) tracks of the island shorelines showed that NIR bands were superior to SWIR bands because of the characteristics of the coral reef coasts, including a lack of foam and suspended sediments (which can affect the NIR wavelength region, if present) and the presence of remnant water on reef flats during low tide (which can affect the SWIR wavelength region). A linear relationship was found between the estimation errors of waterline positions and the spatial resolutions of the NIR sensors. Analysis on estimation errors and image costs showed that Terra ASTER band 3 was the most cost-effective sensor for extracting waterlines with reasonable accuracy. The results serve as general guidelines for using satellite-derived data to estimate intertidal topography and detect and monitor shorelines in coral reef environments.  相似文献   

Geomorphological, paleontological and Sr/Sr isotope analyses of early Pleistocene paleoshorelines to define the uplift of Central Apennines (Italy)     

Marco Mancini  Elisabetta D'Anastasio  Mario Barbieri  Paolo Marco De Martini   《Quaternary Research》2007,67(3):487-501

The eastern border of the Middle Valley of the Tiber River is characterized by several Plio-Pleistocene paleoshorelines, which extend for about 100 km along the western margin of the Central Apennines (Italy). We studied these paleoshorelines by the means of geological and paleontological analyses and new ⁸⁷Sr/⁸⁶Sr isotope analyses. The youngest and uppermost paleoshorelines have been detected and mapped through detailed geologic and stratigraphic surveys, which led to the recognition of nearshore deposits, cliff breccias, alignments of Lithophaga borings, fossil abrasion notches and wave-cut platforms. The altitude of these paleoshorelines decreases almost regularly in the NNW–SSE direction from 480 to 220 m a.s.l. Measurements of the ⁸⁷Sr/⁸⁶Sr isotope ratio have been conducted on corals and mollusks collected from sediments outcropping close to the paleoshorelines. The isotopic dating results indicate numerical values that range between 0.70907 and 0.70910 all over the 100-km outcrop. These results, together with biostratigraphic data, constrain the age of the youngest paleoshorelines to 1.65–1.50 Ma. These paleoshorelines are thus considered almost isochronous, giving an estimated uplift rate of 0.34–0.17 ± 0.03 mm/a moving from NNW to SSE. Shape, length and continuity of the 100-km-long observed movements indicate that the studied paleoshorelines are an important marker of the Quaternary uplift of the Central Apennines.  相似文献   

Role of porolithon algal-ridge growth in the development of the windward coast of Tongatapu Island,Tonga, South Pacific     

Patrick D. Nunn 《地球表面变化过程与地形》1993,18(5):427-439

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海域勘界中的岸线修测及海岸带调查     

林成贵 《现代测绘》2008,31(1):28-30

海岸线是指平均大潮高潮时水陆分界的痕迹线.在实际操作中,如有一线海堤以该海堤为海岸线,如无一线海堤则需根据近期平均大潮高潮位确定海岸线.海岸线修测自调查中间线起始点向两侧各50 km的海岸线进行岸线走向测量,文章分析了勘界工作方法与内容,叙述了海岸线修测的基本内容,进行了海岸线稳定性评估,对海域勘界有实际意义.  相似文献   

1984～2012年海州湾海岸线时空演变研究   总被引：4，自引：2，他引：2  

巢子豪  高一博  谢宏全  卢霞 《海洋科学》2016,40(6):95-100

以Landsat影像为数据源, 通过改进归一化水体指数、二值化、潮位校正模型提取海岸线, 使用数字海岸线分析系统(Digital Shoreline Analysis System, DSAS), 对1984～2012年海州湾海岸线的时空演变进行了研究。结果表明, 1984～2012年间海州湾海岸线整体以4.29 m/a向海洋推进, 其中, 48%的海岸出现侵蚀, 侵蚀速率为22.83 m/a, 侵蚀现象主要出现在大堤修建前的部分粉砂淤泥质海岸。52%的海岸出现淤积, 淤积速率为25.90 m/a, 淤积现象主要出现在人工海岸、河口海岸和受大堤影响的粉砂淤泥质海岸。海岸线时空演变研究有利于科学地规划、开发和管理海洋及其沿岸空间资源, 并保证其环境及经济的可持续发展。  相似文献