Modelling offshore sand waves
نویسنده
چکیده
Offshore activities often encounter large scale sand patterns, such as sand waves. Sand waves are offshore bed forms occurring at water depths of 10 to 50 m. Their wavelengths can lead up to 500 m and their heights are typically several metres. Furthermore, sand waves have been shown to migrate, with typical velocities of up to metres per year. These dynamic sand waves decrease the least navigable depths and so they pose a threat to navigation routes and access channels. To avoid unsafe situations, continuous monitoring and, if necessary, dredging are required. Now, seabed topography charts are made using echo soundings. Combining such sounding techniques with satellite images may lead to more efficient ways to create bathymetry charts. Insight into the dynamics of sand waves can further reduce monitoring costs. Due to the movement of sand waves, pipelines and cables may become exposed. This may result in free spans, which in turn may cause the pipeline to buckle or break. Moreover, anchors and fishing nets may cause damage to the exposed pipelines and cables. In addition, exposed objects may be covered by a sand wave, making it difficult to locate them. Recently, new insight into the migration of sand waves and data-based predictions concerning sand wave amplitude evolution, have been explored. Despite this progress, a number of questions concerning sand wave behaviour remain. It is shown that further knowledge of sand wave behaviour will enable better management strategies and provide information supporting the design of offshore activities.
منابع مشابه
Modelling offshore sand wave evolution
We present a two-dimensional vertical (2DV) flow and morphological numerical model describing the behaviour of offshore sand waves. The model contains the 2DV shallow water equations, with a free water surface and a general bed load formula. The water movement is coupled to the sediment transport equation by a seabed evolution equation. Using this model, we investigate the evolution of sand wav...
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