Coastal and shelf sea hydro-morphodynamic modelling using process-based and data-based techniques

Electronic versions


  • Mohammad Hashemi

    Research areas

  • PhD, School of Ocean Sciences


Recent advances in computer technology and high performance
computing have led to exceptional contributions in our understanding of
the natural environment. Ocean models, in particular, can simulate hypothetical future scenarios when/where observed data are not available, usually, with less cost. Further, ocean modelling is the only tool which enables scientists to evaluate their conceptual models or test their hypotheses in a complex nonlinear ocean system. Nevertheless, the development of complex numerical models should always be accompanied and supported by sufficient observational data in order to set input parameters, select
appropriate model physics, and validate model outputs.
This dissertation, which is presented as a collection of peer-reviewed published journal papers, attempts to answer a number of research questions regarding the hydrodynamics/morphodynamics of the northwest
European shelf seas, using numerical modelling at various scales from
coastal to shelf-seas.
The first part of the dissertation concerns ocean energy, where wave and tidal energy resource as sessment are considered. Some knowledge gaps in wave energy studies such as shortcomings of the existing data bases (e.g.
the Atlas of UK Marine Renewable Energy Resources) are introduced; then, using a higher resolution model with improved physics, spatial and temporal variability of the resource, correlation of the wave energy
resource with the climatic indices as a potential way to understand the
future variability, and effect of tides on shelf-scale resource assessment
using a simplified method, and also coupled wave-tide modelling are presented. Next, some research questions regarding tidal energy resources
at two sites are mentioned: at Orkney - where the European Marine Energy Centre was established - the vertical variability, asymmetry, turbulence, and
ef fect of wind generated currents using a 3-D ocean model are examined; at Skerries, Anglesey –where a tidal-stream array is planned – the effect of waves on the tidal energy resource is investigated, and shown to have significant influence during winter months.
The second part of the dissertation deals with morphodynamic modelling at coastal and shelf scales. Morphodynamic modelling in presence of rotary currents (which are the origin of the formation/maintenance of
many offshore sandbanks) is examined using a suite of numerical models, and a semi-analytical technique developed to estimate the strength of secondary flows. Then, morphodynamic modelling of beach profiles using process
- based (i.e. a cascade of wave, tide, sediment transport and bed level change models) and data - based (i.e. artificial neural network) techniques is presented;the performance and advantages/disadvantages of these approaches are discussed based on a case study in the
Irish Sea. The effect of ocean energy extraction on dynamics of sandbanks, and coastal morphology, is a new research topic of interest which connects the
first and second part of this research, and is considered in prospective future
In the final part of the dissertation , coupled morphodynamic and hydrodynamic modelling , and integrated modelling approach are discussed.
The coupled wave -tide model of the NW European shelf seas as a first step to develop an integrated modelling system for this region is introduced.
The advantages of the coupled model (e.g. improved accuracy in regions where the wave-tide interactions are high) are presented while the potential
issues are discussed: computational cost, increased uncertainty, and lack of
appropriate observations. Further research is underway to apply this model in
morphodynamic simulations. In this respect, prospective future research direction are briefly introduced


Original languageEnglish
Awarding Institution
Award dateJan 2014