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1.
The CLASH database was analyzed for extraction of a set of data having the measured wave heights at both the deep station and the toe of the structure for wave overtopping tests, yielding 1214 data from 29 datasets. Wave heights in front of the toe of the structure were estimated with the Goda formulas and compared with the measured ones. Comparison yielded the overall mean of 1.106 with the standard deviation of 0.155 for the ratio of the estimated to the measured heights, which support the use of the Goda formulas for prediction of nearshore wave heights. Another set of 1215 data having the measured wave heights at the deep station and the wave heights calculated with the SWAN model was also extracted from the CLASH database. A comparative test of the SWAN model using the wave height estimated with the Goda formulas in lieu of the measured height indicated the performance of the SWAN model being similar to that of the Goda formulas, but a tendency of underestimation was noticed in shallow water on a beach of very gentle slope. 相似文献
2.
Traditional wave steepness s=H/L does not define steep asymmetric waves in a random sea uniquey. Three additional parameters characterising single zero-downcross waves in a time series are crest front steepness, vertical asymmetry factor and horizontal asymmetry factor. Results for steepness and asymmetry from zero-downcross analysis of wave data obtained from full scale measurements in deep water on the Norwegian continental shelf in 58 time series are presented. The analysis demonstrates clearly the asymmetry of both “extreme waves” and the highest waves. The period and height of the highest waves are also given together with their correlation to spectral parameters. The measured maximum wave heights are also compared with predicted values of maximum wave heights showing good agreement. 相似文献
3.
响水近岸海域波浪特性研究 总被引：3，自引：0，他引：3
基于响水波浪站累计一整年的现场观测资料，分析了波高和波周期的年内变化特性，研究了波浪的统计特性和波谱特性，并总结归纳了该海域各特征波要素之间以及各波谱参数之间的转换关系。结果显示:响水海域全年有效波高的变化幅度在0.10~2.80 m之间，年平均值为0.56 m；最大波高的变化幅度在0.15~5.58 m之间，年平均值为0.93 m；平均波周期的变化范围为1.91~9.02 s，年平均值为3.90 s。夏季大波高发生频率明显要小于冬、春季节，波浪季节性变化较为显著。就波高和波周期分布而言，通过拟合得出的Weibull分布较为适合本海域实测波高分布和波周期分布。波谱特性方面，本海域双峰谱占到总数的62.5%，且低频谱峰值普遍高于高频谱峰值，其中低频谱峰出现在0.04 Hz左右，高频谱峰则出现在0.15~0.20 Hz之间，分别为本海域涌浪和风浪所集中的频率区间。采用回归分析方法进一步分析了各特征波要素之间以及各波谱参数之间的关系，发现多数波参数之间存在显著的相关性，但受波浪浅水变形影响，各参数之间的比值与理论深水关系有所区别。本文的研究成果可为沿海建筑物的设计以及防灾减灾提供参考和依据。 相似文献
4.
海浪直接影响海上活动和航行安全,同时也蕴藏着巨大的可再生能源,对海浪核心参数之一波高预测至关重要。基于2015年7月～2022年6月山东小麦岛(36°N,120.6°E)站点实测的波高数据,利用反向传播神经网络(back-propagation neural network,BPNN)、长短记忆网络(long short-term memory, LSTM)和支持向量机回归(support vector regression, SVR)三种机器学习模型对波高进行预测,并分析了瑞利参数的引入对预测结果的影响。结果显示,模型输入项引入瑞利参数后,对1 h和6 h波高预测提升效果有限,预测值与测试集的相关性提升不超过0.02,均方根误差的降低不超过0.01 m;在12h和24h的预测中,BPNN和LSTM模型预测结果相关性提升0.03～0.07,均方根误差降低0.02～0.03m,而SVR模型预测结果变化不显著。说明瑞利参数有助改善BPNN和LSTM模型中长期海浪预报。此外,特征扰动方法(机器学习中特征重要性的计算方法之一)验证了瑞利参数在波高预测中的重要性,瑞利参数的引入为波高的机器学习预... 相似文献
5.
An ion exchange technique has been used to determine the copper complexing capacity (CuCC) of strong organic complexing agents at 21 stations across the continental shelf of the southeastern United States and in the western Sargasso Sea. The concentration of dissolved organic carbon (DOC) and total particulate materal (TPM), two pools of potential complexing agents, was also measured at each station. The CuCC ranged from 0.014 to 1.681 μM Cu dm−3 on the inner shelf, from 0.043 to 0.095 μM Cu dm−3 in mid and outer shelf waters, and from < 0.010 to 0.036 μM Cu dm−3 at the Sargasso Sea stations. The correlation between CuCC and both DOC and TPM is highly significant (α < 0.01). Two synoptic surveys of the distribution of DOC and TPM across the shelf showed that DOC ranges from > 3 mg C dm−3 nearshore to <1 mg C dm−3 offshore and that TPM ranges from > 50 mg dm−3 nearshore to <1 mg dm−3 offshore. Both TPM and DOC are most variable on the inner shelf. These data are consistent with CuCC data which indicate that the CuCC of inner shelf waters was relatively high and very heterogeneous. In contrast, DOC, TPM and copper complexing capacity are low and nearly invariant at the Sargasso Sea stations. We present a model of the distribution of complexing agents in different marine environments and hypothesize that the mechanisms underlying differences between environments relate to differences in the source(s) and nature of complexing agents in each system. 相似文献
6.
Long term wave climate of both extreme wave and operational wave height is essential for planning and designing coastal structures.
Since the field wave data for the waters around Korean peninsula is not enough to provide reliable wave statistics, the wave
climate information has been generated by means of long-term wave hindcasting using available meteorological data. Basic data
base of hindcasted wave parameters such as significant wave height, peak period and direction has been established continuously
for the period of 25 years starting from 1979 and for major 106 typhoons for the past 53 years since 1951 for each grid point
of the North East Asia Regional Seas with grid size of 18 km. Wind field reanalyzed by European Center for Midrange Weather
Forecasts (ECMWF) was used for the simulation of waves for the extratropical storms, while wind field calculated by typhoon
wind model with typhoon parameters carefully analyzed using most of the available data was used for the simulation of typhoon
waves. Design wave heights for the return period of 10, 20, 30, 50 and 100 years for 16 directions at each grid point have
been estimated by means of extreme wave analysis using the wave simulation data. As in conventional methodsi of design criteria
estimation, it is assumed that the climate is stationary and the statistics and extreme analysis using the long-term hindcasting
data are used in the statistical prediction for the future. The method of extreme statistical analysis in handling the extreme
events like typhoon Maemi in 2003 was evaluated for more stable results of design wave height estimation for the return periods
of 30–50 years for the cost effective construction of coastal structures. 相似文献
7.
A.J.H.M. Reniers M.J. Groenewegen K.C. Ewans S. Masterton G.S. Stelling J. Meek 《Coastal Engineering》2010
The accuracy of nearshore infragravity wave height model predictions has been investigated using a combination of the spectral short wave evolution model SWAN and a linear 1D SurfBeat model (IDSB). Data recorded by a wave rider located approximately 3.5 km from the coast at 18 m water depth have been used to construct the short wave frequency-directional spectra that are subsequently translated to approximately 8 m water depth with the third generation short wave model SWAN. Next the SWAN-computed frequency-directional spectra are used as input for IDSB to compute the infragravity response in the 0.01 Hz–0.05 Hz frequency range, generated by the transformation of the grouped short waves through the surf zone including bound long waves, leaky waves and edge waves at this depth. Comparison of the computed and measured infragravity waves in 8 m water depth shows an average skill of approximately 80%. Using data from a directional buoy located approximately 70 km offshore as input for the SWAN model results in an average infragravity prediction skill of 47%. This difference in skill is in a large part related to the under prediction of the short wave directional spreading by SWAN. Accounting for the spreading mismatch increases the skill to 70%. Directional analyses of the infragravity waves shows that outgoing infragravity wave heights at 8 m depth are generally over predicted during storm conditions suggesting that dissipation mechanisms in addition to bottom friction such as non-linear energy transfer and long wave breaking may be important. Provided that the infragravity wave reflection at the beach is close to unity and tidal water level modulations are modest, a relatively small computational effort allows for the generation of long-term infragravity data sets at intermediate water depths. These data can subsequently be analyzed to establish infragravity wave height design criteria for engineering facilities exposed to the open ocean, such as nearshore tanker offloading terminals at coastal locations. 相似文献
8.
Results are summarized of an investigation concerned with the development and validation of a method for estimating persistence statistics from cumulative probability distributions. Primary attention has been devoted to estimations of wave height persistence and the motivation has been the requirement to provide estimates of persistence statistics as an additional output for the wave climate synthesis programme called NMIMET which can provide data on a worldwide basis. The opportunity has also been taken to adapt the methods developed for application to estimation of wind speed persistence.A method due to Graham is taken as the starting point and is modified in the light of detailed examination of a number of measured data sets. The method thus derived is shown to be more reliable and much simpler to apply than Graham's method and to give results in good agreement with a range of measured data sets for both exceedance and non exceedance. The measured data used for validation include 2 sets in areas remote from the sites in UK waters used for most of the development. A comparison is also included between persistence statistics estimated using NMIMET output of wave height probabilities from visual wave data and results from measured data. 相似文献
9.
Bathymetry and seismic reflection profiling have revealed a sequence of seven post-Jurassic drowned or buried drainage systems on the southern New England shelf. The basement and younger stream patterns have a dominant southward trend with preferred drainage avenues from the mainland to the middle shelf indicated by superposed valley ground positions from unconformity to unconformity over time. Fluvial action under stable tectonic conditions is inferred by low valley height/width ratios with higher ratios related to ice modification of inner shelf pre-glacial river valleys.Fluvial processes responding to sea-level withdrawals have greatly influenced the shelf's later development. Periodically during post-Paleocene time, sediment from subaerial erosion has been transported to the shelf edge by streams. Deltaic deposition on a subsiding base has controlled outbuilding on the outer shelf where the frequent presence of overlying drainage networks is the result of numerous sea-level regressions. Since Eocene time, sediment has been channelled to the deep sea via Block Canyon and its progenitor.Locally structures created by erosion and glacial deposition have governed drainage direction. On the inner shelf, late Tertiary - early Pleistocene streams were diverted southeastward and southwestward by the magnitude of Long Island's Coastal Plain escarpment and by secondary cuestas between eastern Long Island and Block Island. The probable eastern reach of Dana's southern Sound River valley can be traced from northeastern Long Island across Block Island Sound. An early Woodfordian end moraine of the Wisconsin stage impounded melt waters in Block Island and Rhode Island Sounds. Where the moraine was breached near Block Island, fans were formed adjacent to the water gaps. In Rhode Island Sound the earlier and later Woodfordian end moraines deflected some mainland drainage toward the southwest. 相似文献
10.
The densities of artificial and real Red Sea brines have been measured at 25°C with a vibrating tube densimeter. Measurements were also made on mixtures of Red Sea brines with seawater and pure water. The results have been used to characterize the density—composition relations of waters across the interface of brine and average Red Sea waters. The results for the real and artificial brines are in reasonable agreement.The composition of the brines and mixtures with seawater have been characterized by conductivity measurements of weight diluted samples. The conductivity salinities were found to be conservative to within for the mixtures.The densities of brines and mixtures of brines and seawater were estimated from apparent molal volume data using Young's rule. The calculated densities for all of the solutions were found to be in good agreement with the measured values, demonstrating the applicability of Young's rule to concentrated natural waters. 相似文献
11.
南沙群岛珊瑚岛礁众多,大多数岛礁具有向海坡陡峭、外礁坪比较平缓的特征。将南沙群岛岛礁的迎浪向地形概化为陡坡和缓坡组成的双斜坡,采用FUNWAVE-TVD模式数值模拟概化地形上的波浪,根据模拟的破碎波高分析其拍岸浪特征。对拍岸浪数值模拟结果进行比较分析,向海坡的坡度对拍岸浪影响不大,外礁坪上拍岸浪高随地形坡度增大而略有增大;向海坡和外礁坪交界位置(即坡折点)水深对拍岸浪有比较明显的影响,拍岸浪高随坡折点水深增大而减小;拍岸浪高随入射波高和波周期增大而增大。利用大量的拍岸浪数值模拟数据对国内外5种统计模型进行检验,并且基于拍岸浪数值模拟数据建立了3种南沙群岛岛礁拍岸浪统计模型,计算结果显示这些模型适用性较好。 相似文献
12.
A spectral wind wave model SWAN (Simulation WAves Nearshore) that represents the generation, propagation and dissipation of waves was applied to Lake Okeechobee. This model includes the effects of refraction, shoaling, and blocking in wave propagation. It accounts for wave dissipation by whitecapping, bottom friction, and depth-induced wave breaking. The wave–wave interaction effect also is included in this model. Measurements of wind and wave heights were made at different stations and different time periods in Lake Okeechobee. Significant wave height values were computed from the recorded data. The correlation between wind stress and significant wave height also was analyzed. A 6-day simulation using 1989 data was conducted for model calibration. Another 6-day simulation using 1996 data was conducted for model verification. The simulated significant wave heights were found to agree reasonably well with measured significant wave heights for calibration and verification periods. Agreement between observed and simulated values was based on graphical comparisons, mean, absolute and root mean square errors, and correlation coefficient. Comparisons showed that the model reproduced both general observed trends and short term fluctuations. 相似文献
13.
A procedure to correlate extreme wave heights and extreme water levels in coastal waters using numerical models together with joint probability analysis has been proposed. A third-generation wave model for wave simulation and a three-dimensional flow model for water level simulation are coupled through the surface atmospheric boundary layer. The model has been calibrated and validated against wind, wave and water level data collected in the coastal waters of Hong Kong. The annual maximum wave height and the concomitant water level have been obtained by simulating the annual extreme typhoon event for 50 consecutive years. The results from bivariate extreme value analysis of the simulated data show that the commonly used empirical method may lead to underestimation of the design water level. 相似文献
14.
The SWAN wave model is typically designed for wave simulations in the near-shore region and thus is selected for evaluating its applicability on typhoon waves in the coastal waters around Taiwan Island. Numerical calculations on processes of wave heights and periods during the passages of four representative typhoons are compared with measured data from field wave stations on both east and west coasts. The results have shown that waves due to typhoons of paths 2, 3 and 4 can be reasonably simulated on east coastal waters. However, discrepancies increase for the simulated results on west coastal waters because the island's central mountains partly damage the cyclonic structures of the passing-over typhoons. It is also found that the included nested grid scheme in SWAN could improve the accuracy of simulations in coastal waters to facilitate further engineering practices. 相似文献
15.
Waves at 15 m water depth in the northern Arabian Sea are measured during the summer monsoon for a period of 45 days and the characteristics are described. The significant wave height varied from 1.1 to 4.5 m with an average value of 2.5 m. 75% of the wave height at the measurement location is due to the swells arriving from the south-west and the remaining is due to the seas from south-west to north-west. Wave age of the measured data indicates that the waves in the nearshore waters of northern Arabian Sea during the summer monsoon are swells with young sea. 相似文献
16.
A study of sea surface wave propagation and its energy deformation was carried out using field observations and numerical experiments over a region spanning the midshelf of the South Atlantic Bight (SAB) to the Altamaha River Estuary, GA. Wave heights on the shelf region correlate with the wind observations and directional observations show that most of the wave energy is incident from the easterly direction. Comparing midshelf and inner shelf wave heights during a time when there was no wind and hence no wave development led to an estimation of wave energy dissipation due to bottom friction with corresponding wave dissipation factor of 0.07 for the gently sloping continental shelf of the SAB. After interacting with the shoaling region of the Altamaha River, the wave energy within the estuary becomes periodic in time showing wave energy during flood to high water phase of the tide and very little wave energy during ebb to low water. This periodic modulation inside the estuary is a direct result of enhanced depth and current-induced wave breaking that occurs at the ebb shoaling region surrounding the Altamaha River mouth at longitude 81.23°W. Modelling results with STWAVE showed that depth-induced wave breaking is more important during the low water phase of the tide than current-induced wave breaking during the ebb phase of the tide. During the flood to high water phase of the tide, wave energy propagates into the estuary. Measurements of the significant wave height within the estuary showed a maximum wave height difference of 0.4 m between the slack high water (SHW) and slack low water (SLW). In this shallow environment these wave–current interactions lead to an apparent bottom roughness that is increased from typical hydraulic roughness values, leading to an enhanced bottom friction coefficient. 相似文献
17.
The extreme significant wave heights and the corresponding wave periods were predicted for return periods of 12, 25, 50, 100 and 200 yr for 19 different locations in Kuwaiti territorial waters. Though the total coast length of Kuwait is only about 500 km including all islands and the total area of the Kuwaiti territorial water is about 7611 km2, the extreme significant wave height vary from 1.86 to 4.02 m for 100 yr return period, among these 19 locations. In general Weibull distribution is found to fit the data well compared to the Gumbel distribution. The input wave data for the present work is obtained by hind casting waves using a WAM model. Wave data is hindcasted for a total period of 12 yr, starting from 1 January 1993 to 31 December 2004. From the joint probability of wave height and wave period, a simple polynomial relationship is obtained between the significant wave height and mean period for all the 19 locations. It is found that the wave period for wave heights of 100 yr return period cannot exceed 6.5 s. A large number of coastal projects are in progress and many new projects are planned for the near future in the Kuwaiti territorial waters. The results of the present study will be highly useful for optimal design of these projects. 相似文献
18.
南沙海区风浪分析与计算 总被引：3，自引：0，他引：3
根据南沙海区风浪实测资料,阐述了南沙海区波高的分布规律。应用相关分析法,通过多元回归计算,得出波要素与风速、风时之间的关系。对波高、波周期的相互关系作了统计分析并利用永署礁海洋观测站1990年1～7月的实测资料对计算结果作了验证。结果表明,南沙海区波高、波周期的计算值与实测值基本吻合。 相似文献
19.
20.
Ching-Piao Tsai Hong-Bin Chen Hwung-Hweng Hwung Ming-Jen Huang 《Ocean Engineering》2005,32(3-4):469-483
Estimation of the wave height transformation of shoaling and breaking is essential for the nearshore hydrodynamics and the design of coastal structures. Many empirical formulas have been well recognized to the wave height transformation, but most of them were only applicable for gentle slopes. This paper reports the experimental results of wave shoaling and breaking over the steep slopes to examine the applicability of the previous empirical formulas. Two steep bottom slopes of 1/3 and 1/5, and one gentle slope of 1/10 were conducted in the present experiments. Experimental results show that the shoaling distance of steep slopes become short and the surface waves may be partially reflected from the steep bottom, thus the estimation of wave shoaling using the well-known previous formula did not conform completely to the experimental results. The previous empirical formulas for the wave breaking criteria were also examined, and the modified equations to the steep beaches were proposed in this work. A numerical model was finally adopted to calculate the wave height transformation in the surf zone by introducing the modified breaking index. 相似文献