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Quantifying the influence of tidal sand wave orientation on form roughness

Bedon Pineda, C.H. (2024) Quantifying the influence of tidal sand wave orientation on form roughness.

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Abstract:The Netherlands Continental Shelf, a dynamic seabed dominated by tides is characterized by the presence of sand waves. Current hydrodynamic models like the Dutch Continental Shelf Model lack the resolution to capture these bedforms, relying solely on water level observations for calibration. Using Delft3D numerical model, tidal flow simulations over a morphostatic bed were conducted. Our aim is to analyze the influence of sand wave field orientation on form roughness. Four criteria were established to quantify form roughness based on amplitude and phase to best replicate the depth-averaged flow and sea surface elevation over sand waves. Our findings reveal that increasing height and decreasing wavelength lead to higher form roughness. Orientation impacts roughness differently in each hemisphere, with the Coriolis effect playing a significant role. At the equator, form roughness is symmetrical for some criteria but varies with rotation direction for others. Notably, the phase-based criteria are highly sensitive to the starting bathymetric phase. This study highlights the limitations of mimicking flow over sand waves with solely roughness adjustments in flat seabed models. Our method offers a valuable approach for incorporating bedform information into model calibration. This approach leads to a more physics-based representation of roughness compared to current practices.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:56 civil engineering
Programme:Civil Engineering and Management MSc (60026)
Link to this item:https://purl.utwente.nl/essays/100240
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