Dynamics and stratigraphy of a tidal sand ridge in the Bristol Channel (Nash Sands banner bank) from repeated high‐resolution multibeam echo‐sounder surveys

Sedimentology ◽  
2021 ◽  
Author(s):  
Neil C. Mitchell ◽  
Rhodri Jerrett ◽  
Rob Langman
Keyword(s):  
High Resolution ◽  
Sand Ridge ◽  
Tidal Sand ◽  
Echo Sounder

Sand Wave Migration and its Factors on Giant Sand Ridge in Taiwan Strait

2020 ◽  
Author(s):  
Yin-Hsuan Liao ◽  
Ho-Han Hsu ◽  
Jyun-Nai Wu ◽  
Tzu-Ting Chen ◽  
Eason Yi-Cheng Yang ◽  
...  
Keyword(s):  
High Resolution ◽  
Taiwan Strait ◽  
Sand Wave ◽  
Sand Ridge ◽  
Elevation Change ◽  
Seismic Profiles ◽  
Migration Patterns ◽  
Sand Waves ◽  
And Migration ◽  
Wave Migration

<p>        Submarine sand waves are known to be induced by tidal currents and their migration has become an important issue since it may affect seafloor installations. In Taiwan Strait, widely spreading sand waves have been recognized on the Changyun Ridge, a tide-dominated giant sand ridge offshore western Taiwan. However, due to lacking of high-resolution and repeated geophysical surveys before, detailed characteristics and migrating features of the sand waves in Taiwan Strait were poorly understood. As new multibeam bathymetric and seismic data were collected repeatedly during 2016 - 2018 for offshore wind farm projects, we can now advance the understanding of sand wave characteristics and migration patterns in the study area. We apply a geostatistical analysis method on bathymetry data to reveal distribution and spatial characteristics of the sand waves, and estimate its migration pattern by using an updated spatial cross-correlation method. Then, sedimentary features, internal structures and thicknesses of sand waves are observed and estimated on high-resolution seismic profiles. Our results show that the study area is mostly superimposed by multi-scaled sandy rhythmic bed forms. However, the geomorphological and migrating characteristics of the sand waves are complicated. Their wavelengths range from 80 to 200 m, heights range from 1.5 to 8 m, and crests are generally oriented in the WNW-ESE direction. Obvious sand wave migration was detected from repeated high-resolution multi-beam data between 2016 and 2018, and migration distances can be up to ~150 m in 15 months. The average elevation change of the seafloor over the whole survey area is ~3.0 m, with a maximum value of 6.9 m. Moreover, the sand waves can migrate over 30 m with ~2.5 m elevation change in 2 months and migrate over 5 m with ~1 m elevation change in 15 days. The results also show that the orientation of wave movement can be reversed even within a small distance. By identifying the base of sand wave on seismic profiles, the thicknesses of sand waves are found ranging from 1 to 10 meters. The base of wave structure become slightly deeper from nearshore to offshore. Our results indicate that the thickness of sand waves increases with degree of asymmetry and migration rate. By bathymetric and reflection seismic data analyses, systematic spatial information of sand waves in the study area are established, and we suggest that not only tidal currents can affect sand wave migration patterns, but also wave structures and thicknesses play important roles in sand wave migrating processes and related geomorphological changes.</p>

Shallow Water High Resolution Multi-Beam Echo Sounder

2008 ◽  
Author(s):  
Haisen Li ◽  
Bin Yao ◽  
Tian Zhou ◽  
Yukuo Wei ◽  
Baowei Chen ◽  
...  
Keyword(s):  
High Resolution ◽  
Shallow Water ◽  
Echo Sounder

scholarly journals Obtaining High-Resolution Seabed Topography and Surface Details by Co-Registration of Side-Scan Sonar and Multibeam Echo Sounder Images

2019 ◽  
Vol 11 (12) ◽  
pp. 1496 ◽  
Author(s):  
Shang ◽  
Zhao ◽  
Zhang
Keyword(s):  
High Resolution ◽  
Template Matching ◽  
High Accuracy ◽  
Transformation Model ◽  
Base Line ◽  
Initial Image ◽  
Side Scan Sonar ◽  
Speeded Up Robust Features ◽  
Seabed Topography ◽  
Echo Sounder

Side-scan sonar (SSS) is used for obtaining high-resolution seabed images, but with low position accuracy without using the Ultra Short Base Line (USBL) or Short Base Line (SBL). Multibeam echo sounder (MBES), which can simultaneously obtain high-accuracy seabed topography as well as seabed images with low resolution in deep water. Based on the complementarity of SSS and MBES data, this paper proposes a new method for acquiring high-resolution seabed topography and surface details that are difficult to obtain using MBES or SSS alone. Firstly, according to the common seabed features presented in both images, the Speeded-Up Robust Features (SURF) algorithm, with the constraint of image geographic coordinates, is adopted for initial image matching. Secondly, to further improve the matching performance, a template matching strategy using the dense local self-similarity (DLSS) descriptor is adopted according to the self-similarities within these two images. Next, the random sample consensus (RANSAC) algorithm is used for removing the mismatches and the SSS backscatter image geographic coordinates are rectified by the transformation model established based on the correct matched points. Finally, the superimposition of this rectified SSS backscatter image on MBES seabed topography is performed and the high-resolution and high-accuracy seabed topography and surface details can be obtained.

High-resolution swath sonar investigation of sand ridge, dune and ribbon morphology in the offshore environment of the New Jersey margin

1999 ◽  
Vol 161 (2-4) ◽  
pp. 307-337 ◽  
Author(s):  
John A Goff ◽  
Donald J.P Swift ◽  
Catherine S Duncan ◽  
Larry A Mayer ◽  
John Hughes-Clarke
Keyword(s):  
New Jersey ◽  
High Resolution ◽  
Sand Ridge

Types and Acoustic Reflection Characteristics of Geo-Hazards in the Western of the North Yellow Sea

2011 ◽  
Vol 137 ◽  
pp. 374-381
Author(s):  
Xiao Hui Chen ◽  
Xun Hua Zhang ◽  
Ri Hui Li
Keyword(s):  
Yellow Sea ◽  
Research Progress ◽  
Sand Wave ◽  
Sand Ridge ◽  
Engineering Construction ◽  
Acoustic Reflection ◽  
North Yellow Sea ◽  
The North ◽  
Tidal Sand ◽  
Marine Engineering

The geological environments in the western of the North Yellow Sea(NYS) are comparatively complicated and pregnant with various geo-hazards. High-resolution sub-bottom seismic data and previous research progress have been used to examine marine geo-hazards’ types, acoustic reflection features, origins and disaster mechanisms. The results indicate that the hazardous types are complicated and multiple in the western of the NYS, including tidal sand ridge, sand wave, tidal erosion gutter, underwater shoal, shallow gas, buried paleo-channel, active fault, irregular bedrock and so on. They have some connections as well as differentiations in their distribution and genesis. This paper can provide the theoretical basis on marine engineering, disaster prevention and mitigation in the western of the NYS . More attention should be given to severe geo-hazards that can constitute direct or potential hazards to the economic development and engineering construction.

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