2D and 3D Hydrodynamic and Morphodynamic Modelling of Offshore Sandbanks in the North Sea

The coastal zone is an important resource both socially and economically. Globally, coastal zones are under increasing threat from the effects of climate change, erosion and flooding. Understanding the mechanisms of coastal processes is key to the long term management and protection of the coastal zone and its resources.

Sandbanks are the largest of the bedform features encountered in many tidal seas and continental shelves. They are typically up to 60km in length, 6km in width and several metres in height. They are located in regions where there is an abundant supply of sediments with sufficiently strong tidal currents to move them. Sandbanks play an important role in coastal zone management and engineering. Primarily they act as a natural method of coastal defence, protecting the adjacent shorelines from the effects of coastal erosion. They also present a hazard for navigational channels and are a natural habitat for a wide range of biodiversity. Sandbanks also provide a source of sediment for sand mining and are often used as sites for offshore construction such as wind farms and oil/gas pipelines.

This research aims to model the hydrodynamics and morphodynamics of the sandbanks in the southern bight of the North Sea, UK. The main objective is to determine the impact of the vertical velocity component on the recirculation of the flow and on the suspended and bedload sediment transport rates and how this affects the long term evolution of a sandbank under normal and storm conditions.

The study site for this research is the southern bight of the North Sea covering an area of roughly 85600km$^2$. This research uses the TELEMAC suite comprising of TELEMAC2D for 2D hydrodynamics, TELEMAC3D for 3D hydrodynamics and SISYPHE for 2D and 3D morphodynamics. This paper presents the details of model setup, calibration process and both 2D and 3D hydrodynamic results focussed on an area of sandbanks in the domain.