scholarly journals Random wave-driven seabed shear stress estimation in shallow water based on long-term variation of deep water wave conditions

2017 ◽  
Vol 232 (3) ◽  
pp. 351-357
Author(s):  
Dag Myrhaug
Keyword(s):  
Shear Stress ◽  
Shallow Water ◽  
Deep Water ◽  
Random Wave ◽  
Wave Statistics ◽  
Stress Estimation ◽  
Deep Water Wave ◽  
Northern North Sea

This article presents a simple analytical method giving estimates of wave-driven bottom stresses for very rough and mud seabeds in shallow water from long-term wave statistics in deep water. The results are exemplified using long-term in situ wave statistics from the Northern North Sea and by providing examples representing realistic field conditions. The results can be used to make estimates of the seabed shear stress in estuarine and coastal waters based on, for example, global wave statistics.

scholarly journals Estimation of wave power in shallow water using deep water wind and wave statistics

2020 ◽  
pp. 147509022096928
Author(s):  
Dag Myrhaug
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Mean Value ◽  
Wave Power ◽  
Coastal Zones ◽  
Ocean Area ◽  
Wave Statistics ◽  
Deep Water Wave ◽  
Northern North Sea ◽  
Wave Power Potential

The article addresses how the wave power in shallow water can be estimated based on available wind and wave statistics for a deep water ocean area. The average statistical properties of the wave power in shallow water expressed in terms of the mean value and the standard deviation are presented. Results are exemplified by using long-term wind and wave statistics from the same ocean area in the Northern North Sea. Overall, it appears that there is agreement between the results based on these inputs from wind and wave statistics. The presented analytical method should be useful for making preliminary estimates of the wave power potential in shallow water using either available deep water wind statistics or deep water wave statistics, which enhances the possibilities for assessing further the wave power potential in, for example, near-coastal zones.

Assessment of random wave energy dissipation due to submerged aquatic plants in shallow water using deep water wave conditions

2021 ◽  
pp. 147509022110399
Author(s):  
Dag Myrhaug ◽  
Pierre-Yves Henry
Keyword(s):  
Energy Dissipation ◽  
Shallow Water ◽  
Deep Water ◽  
Aquatic Plants ◽  
Wave Energy ◽  
Water Wave ◽  
Random Wave ◽  
Wave Energy Dissipation ◽  
Submerged Aquatic Plants ◽  
Deep Water Wave

This article addresses the random wave energy dissipation due to submerged aquatic plants in shallow water based on deep water wave conditions including estimation of wave damping. The motivation is to provide a simple engineering tool suitable to use when assessing random wave damping due to small patches of plants in shallow water. Examples of application for typical field conditions are provided. The present method versus common practice is discussed. A possible application of the outcome of this study is that it can be used as a parameterization of wave energy dissipation due to vegetation patches of limited size in operational estuarine and coastal circulation models.

scholarly journals Taphonomy and ecology of deep-water Ediacaran organisms from northwestern Canada

1992 ◽  
Vol 6 ◽  
pp. 219-219 ◽  
Author(s):  
Guy M. Narbonne ◽  
Robert W. Dalrymple
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Microbial Mats ◽  
Bedding Plane ◽  
Thin Layers ◽  
Sea Bottom ◽  
Windermere Supergroup ◽  
Storm Wave ◽  
Upper Slope

Although most occurrences of Ediacaran fossils are from shallow-shelf deposits, taxonomically-similar assemblages have recently been described from a 2.5 km-thick succession of dark mudstones and turbiditic sandstones in the Windermere Supergroup of the Mackenzie Mountains, northwestern Canada. The paleogeographic position (20-40 km seaward of the shelf edge), abundant evidence of mass flow, and the complete absence of in situ shallow-water features imply that deposition took place on a slope considerably below storm wave-base. Ediacaran fossils were not observed in axial trough deposits (lower parts of the Twitya and Sheepbed formations), but megafossils occur sporadically in lower to middle slope deposits higher in the same formations. Megafossils and trace fossils are present in upper slope settings (Blueflower Formation) at the top of the Ediacaran succession. The megafossil assemblage varies stratigraphically, but in all formations is dominated by discoid forms (e.g. Cyclomedusa, Ediacaria, Nimbia); frondose forms and vendomiids are very rare.Megafossils are preserved mainly as positive features on the soles of thin turbidite beds. Most fossiliferous beds begin with the rippled layer of the turbidite (Tc), but a few begin with the graded (Ta) or parallel-laminated (Tb) layer. Consistent orientation and high relief of individuals, evidence of mutual deformation during growth of adjacent organisms, and other taphonomic features imply that virtually all of the taxa represent benthic polypoid and frond-like organisms (not jellyfish). Slump structures occur commonly in the sandstone fill of fossils, suggesting that many of the organisms were buried alive by the turbidite and later decomposed. Other individuals, even on the same bedding plane, exhibit graded to laminated fill identical to that of the overlying turbidite bed, indicating that the depressions on the sea bottom produced by these individuals were empty at the time of turbidite deposition. Escape structures are absent, suggesting that the Ediacaran organisms were not capable of burrowing up through even thin layers of sand.Ediacaran megafossils are invariably preserved on black, wrinkled surfaces similar to those elsewhere interpreted as microbial mats. Molding of delicate features (including tentacles), preservation of open molds as negative epireliefs, and sedimentological evidence of considerable cohesion of these surfaces relative to the underlying turbiditic muds (Td,e) supports this interpretation, and suggests that microbial mats were as important in the preservation of these deep-water Ediacara faunas as they were in their shallow-water equivalents. The presence of the wrinkled mats and their associated Ediacaran fossils almost exclusively in the pyritic intervals of the succession suggests that both may have lived under exaerobic conditions in this deep-water setting.

scholarly journals Modeling Water Quality Parameters Using Landsat Multispectral Images: A Case Study of Erlong Lake, Northeast China

2021 ◽  
Vol 13 (9) ◽  
pp. 1603
Author(s):  
Bazel Al-Shaibah ◽  
Xingpeng Liu ◽  
Jiquan Zhang ◽  
Zhijun Tong ◽  
Mingxi Zhang ◽  
...  
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Shallow Water ◽  
Deep Water ◽  
Northeast China ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Multispectral Images ◽  
Landsat Images

Erlong Lake is considered one of the largest lakes in midwest Jilin, China, and one of the drinking water resources in neighboring cities. The present study aims to explore the usage of Landsat TM5, ETM7, and OLI8 images to assess water quality (V-phenol, dissolved oxygen (DO), NH4-N, NO3-N) in Erlong Lake, Jilin province, northeast China. Thirteen multispectral images were used in this study for May, July, August, and September in 2000, 2001, 2002, and October 2020. Radiometric and atmospheric corrections were applied to all images. All in situ water quality parameters were strongly correlated to each other, except DO. The in situ measurements (V-phenol, dissolved oxygen, NH4-N, NO3-N) were statistically correlated with various spectral band combinations (blue, green, red, and NIR) derived from Landsat imagery. Regression analysis reported that there are strong relationships between the estimated and retrieved water quality from the Landsat images. Moreover, in calibrations, the highest value of the coefficient of determination (R2) was ≥0.85 with (RMSE) = 0.038; the lowest value of R2 was >0.30 with RMSE= 0.752. All generated models were validated in different statistical indices; R2 was up to 0.95 for most cases, with RMSE ranging from 1.390 to 0.050. Finally, the empirical algorithms were successfully assessed (V-phenol, dissolved oxygen, NH4-N, NO3-N) in Erlong Lake, using Landsat images with very good accuracy. Both in situ and model retrieved results showed the same trends with non-significant differences. September of 2000, 2001, and 2002 and October of 2020 were selected to assess the spatial distributions of V-phenol, DO, NH4-N, and NO3-N in the lake. V-phenol, NH4-N, and NO3-N were reported low in shallow water but high in deep water, while DO was high in shallow water but low in deep water of the lake. Domestic sewage, agricultural, and urban industrial pollution are the most common sources of pollution in the Erlong Lake.

scholarly journals OCEAN WAVE STATISTICS FROM FNWC SPECTRAL ANALYSES

1976 ◽  
Vol 1 (15) ◽  
pp. 13
Author(s):  
Warren C. Thompson ◽  
F. Michael Reynolds
Keyword(s):  
Deep Water ◽  
Water Wave ◽  
Spectral Element ◽  
Coastal Engineering ◽  
Ocean Wave ◽  
Frequency Of Occurrence ◽  
Numerical Weather ◽  
Significant Wave ◽  
Wave Statistics ◽  
Deep Water Wave

Climatological wave data that may be shoaled and refracted from a deep-water wave station can be compiled in two forms from spectral ocean wave analyses produced by the Fleet Numerical Weather Central at Monterey, California: (1) significant wave statistics, which are similar to statistical tables currently in use, and (2) spectral element statistics, which give the frequency of occurrence of energy densities contained in a matrix of 15 frequency bands and 12 direction bands. Experimental formats of both types of statistical compilations are presented, their properties are examined, and the coastal engineering applications of these statistics are discussed.

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