The trends and controls of the coastal bedload sediment transport paths (the Needles to St. Catherine's Point, Isle of Wight) : a medium to large scale numerical computer model
The whole of the Isle of Wight coastline is subject to erosion. The coastline development
is predominantly controlled by the geology.
The south-west coastline of the Isle of Wight between The Needles to St. Catherine's
Point is the subject of this enquiry because it has a relatively high energy input, in terms
of waves and tidal currents, which promotes responses between process and form over
relatively short periods of time. Because of this, the measurement of processes and their
modelling can be a difficult problem.
The trends and controls of the coastal bedload sediment transport system are defined
by developing a model for the sediment transport paths of this coastal stretch. The coarse
bedload is chosen for emphasis because of its importance in the sediment bulk of the
study area. The coastal bedload sediment transport model is translated into a coarse
scale numerical computer model which can be used to answer questions about sediment
transport paths for different sediment sizes, wave conditions and water levels.
The main questions asked are: What effects do the 'controls', angle of wave approach
and water level, have on bedload sediment transport? What are the bedload sediment
transport pathways for waves of 35:1 year, 5:1 year and 1:50 years frequency and for
common, rare and extremely rare swell waves?
It is an important conclusion of this thesis that the results show that the cell boundaries
are dynamic and that they are valid for only one wave and water level specification. The
model can be used to interpret the bedload sediment transport system for a long coastline.
Coastal bedload sediment erosion and accumulation scenarios can be formulated using the
model. Furthermore the submodel results can be combined to design bedload sediment
Important points with respect to the Isle of Wight coast and its management are that
erosion is clearly episodic in time and space and related to wave regime. The general
pathways are west to east alongshore and offshore sediment transport paths and rips do