The effect of seabed roughness on passive fathometer measurements

2021 ◽  
Vol 150 (4) ◽  
pp. A314-A314
Author(s):  
Derek Olson
Keyword(s):  
Seabed Roughness

scholarly journals Comparison of mechanical disturbance in soft sediments due to tickler-chain SumWing trawl vs. electro-fitted PulseWing trawl

2018 ◽  
Vol 76 (1) ◽  
pp. 312-329 ◽  
Author(s):  
Jochen Depestele ◽  
Koen Degrendele ◽  
Moosa Esmaeili ◽  
Ana Ivanović ◽  
Silke Kröger ◽  
...  
Keyword(s):  
Particle Size ◽  
Penetration Depth ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Strength Analysis ◽  
Sediment Profile ◽  
Soft Sediments ◽  
Sediment Layers ◽  
Micro Topography ◽  
Seabed Roughness

Abstract Tickler-chain SumWing and electrode-fitted PulseWing trawls were compared to assess seabed impacts. Multi-beam echo sounder (MBES) bathymetry confirmed that the SumWing trawl tracks were consistently and uniformly deepened to 1.5 cm depth in contrast to 0.7 cm following PulseWing trawling. MBES backscatter strength analysis showed that SumWing trawls (3.11 dB) flattened seabed roughness significantly more than PulseWing trawls (2.37 dB). Sediment Profile Imagery (SPI) showed that SumWing trawls (mean, SD) homogenised the sediment deeper (3.4 cm, 0.9 cm) and removed more of the oxidised layer than PulseWing trawls (1 cm, 0.8 cm). The reduced PulseWing trawling impacts allowed a faster re-establishment of the oxidised layer and micro-topography. Particle size analysis suggested that SumWing trawls injected finer particles into the deeper sediment layers (∼4 cm depth), while PulseWing trawling only caused coarsening of the top layers (winnowing effect). Total penetration depth (mean, SD) of the SumWing trawls (4.1 cm, 0.9 cm) and PulseWing trawls (1.8 cm, 0.8 cm) was estimated by the depth of the disturbance layer and the layer of mobilized sediment (SumWing = 0.7 cm; PulseWing trawl = 0.8 cm). PulseWing trawls reduced most of the mechanical seabed impacts compared to SumWing trawls for this substrate and area characteristics.

Numerical study of the turbulent eddies generated by the seabed roughness. Case study at a tidal power site

2020 ◽  
Vol 97 ◽  
pp. 102082 ◽  
Author(s):  
Philippe Mercier ◽  
Mikaël Grondeau ◽  
Sylvain Guillou ◽  
Jérôme Thiébot ◽  
Emmanuel Poizot
Keyword(s):  
Numerical Study ◽  
Tidal Power ◽  
Turbulent Eddies ◽  
Seabed Roughness

Seabed roughness parameters for the Malta Plateau from joint backscatter and reflection inversion

2013 ◽  
Vol 133 (5) ◽  
pp. 3252-3252
Author(s):  
Gavin Steininger ◽  
Charles W. Holland ◽  
Stan E. Dosso ◽  
Jan Dettmer
Keyword(s):  
Roughness Parameters ◽  
Seabed Roughness

scholarly journals Insights on the design of free-spanning pipelines

2015 ◽  
Vol 373 (2033) ◽  
pp. 20140111 ◽  
Author(s):  
M. Drago ◽  
M. Mattioli ◽  
R. Bruschi ◽  
L. Vitali
Keyword(s):  
Multidisciplinary Approach ◽  
Limit State ◽  
Wave Action ◽  
Shallow Waters ◽  
Design Assessment ◽  
Direct Wave ◽  
Fatigue Limit State ◽  
Seabed Roughness

The design of free-spanning pipelines is performed with the aim of ensuring their integrity against permanent loads generated by seabed roughness, functional loads induced by internal pressure and temperature, and dynamic loads induced by marine currents and direct wave action. In particular, a load and resistance factored design is applied that focuses on extreme environmental loads, and a fatigue limit state approach is applied as a consequence of free-span dynamics due to vortex shedding-induced vibration and direct wave action. The pipeline free-span scenario can be permanent, when generated by seabed roughness, or characterized by short- to long-term evolution, when generated by seabed mobility and scouring in shallow waters. Free-span analysis is generally a task involving a number of disciplines and should be carried out using a multidisciplinary approach. The paper illustrates various themes related to free-span analysis: (i) free-span scenarios, (ii) characterization of the environment from deep to shallow water related to proper seabed properties, (iii) hydrodynamic load regimes, (iv) pipeline free-span design assessment aiming to reduce overstress and fatigue damage, (v) erodible seabed mobility and local scour, and (vi) some experiences of inspection surveys chosen as representative of a free-spanning pipeline in sandy soils.

Seabed roughness measurement using the multibeam-subbottom-profiler SBP120

2018 ◽  
Vol 144 (3) ◽  
pp. 1972-1972
Author(s):  
Samuel Pinson ◽  
Benjamin Barbier ◽  
Charles W. Holland ◽  
Yann Stéphan
Keyword(s):  
Roughness Measurement ◽  
Subbottom Profiler ◽  
Seabed Roughness
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