Investigation of deep sea shelf sandbank dynamics driven by highly energetic tidal flows

•Sand coverage in Inner Sound channel (PF) is described via interrogation of numerous data sources available in this area.•An overview of the complex 3D tidal flow regime in the Inner Sound channel (PF) is presented.•The morphodynamic environment of the Inner Sound channel (PF) is modelled in detail.•Sediment transport mechanisms associated with morphodynamics of deep sea shelf sandbanks are revealed.

In this paper we describe a numerical modelling study carried out to investigate the prevailing sediment dynamics of two large sandbanks located at a site designated for future development of tidal stream energy extraction, in the Inner Sound Channel of Pentland Firth, Scotland, UK. A calibrated and validated 3D Delft3D hydrodynamic model covering Pentland Firth channel was combined with a morphodynamic model. The sea bed changes occurring around the sandbanks during a period of two spring-neap tidal cycles are described and discussed in detail. It was found that both sandbanks, which are located in a deep shelf region (depths > 18 m), are morphodynamically active and their existence and integrity are strongly linked with the existing hydrodynamic regime.