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Chapter 6
Wave Run-up and Overtopping
6.1 Introduction
Along a coast, the water levels tend to change in time based up on the
tidal fluctuations and wave climate which comprises of two components.
One is dynamic about the mean water level due to the wave action along
the shore and another is the static with gradually varying of water level
associated with wave set up, astronomical tides and storm surge (abnormal
rise of water level). Wave deformation occurs when it propagates from the
offshore to shallow water, and when it interacts with Coastal structures like
breakwaters, sea walls, revetments, groins and dykes it run-ups and sometimes flows over the structure or the coast, which is termed as overtopping.
The physical processes of wave run-up and overtopping are the two major
complex phenomena that influence the design of seawalls exposed to wave
attack. In the design of breakwater, the crest élévation from the still water
level is established based on the maximum wave run-up height. The wave
run-up and overtopping are influenced by factors like geometrical parameters such as slope, free board and crest width, structural parameters that
includes porosity, permeability, stone shape, size and layer thickness, and
hydraulic parameters such as mean sea level, celerity, wave height distribution, spectral shape, wave direction, wave grouping, wave period, wave
breaking and currents.
The wave run-up and overtopping significantly affects the functional efficiency which involves protection of shipment, and, to a certain extent, the
structural stability of Coastal structures as well as Coastal flooding. Though,
the overtopping sometimes may not be due to a structure, the splash of
water by wind carried spray may cause inconvenience to the residents close
to the area on the landward side along the coast. On the lee side of low crest
breakwaters, the said phenomena lead to damages of the reclaimed areas.
In such cases, breakwaters with higher crest élévation should be adopted
to minimize the overtopping and to provide good shelter, on the contrary,
this involves higher investment as well as it affects the aesthetics. As the
Chapter 6
Wave Run-up and Overtopping
6.1 Introduction
Along a coast, the water levels tend to change in time based up on the
tidal fluctuations and wave climate which comprises of two components.
One is dynamic about the mean water level due to the wave action along
the shore and another is the static with gradually varying of water level
associated with wave set up, astronomical tides and storm surge (abnormal
rise of water level). Wave deformation occurs when it propagates from the
offshore to shallow water, and when it interacts with Coastal structures like
breakwaters, sea walls, revetments, groins and dykes it run-ups and sometimes flows over the structure or the coast, which is termed as overtopping.
The physical processes of wave run-up and overtopping are the two major
complex phenomena that influence the design of seawalls exposed to wave
attack. In the design of breakwater, the crest élévation from the still water
level is established based on the maximum wave run-up height. The wave
run-up and overtopping are influenced by factors like geometrical parameters such as slope, free board and crest width, structural parameters that
includes porosity, permeability, stone shape, size and layer thickness, and
hydraulic parameters such as mean sea level, celerity, wave height distribution, spectral shape, wave direction, wave grouping, wave period, wave
breaking and currents.
The wave run-up and overtopping significantly affects the functional efficiency which involves protection of shipment, and, to a certain extent, the
structural stability of Coastal structures as well as Coastal flooding. Though,
the overtopping sometimes may not be due to a structure, the splash of
water by wind carried spray may cause inconvenience to the residents close
to the area on the landward side along the coast. On the lee side of low crest
breakwaters, the said phenomena lead to damages of the reclaimed areas.
In such cases, breakwaters with higher crest élévation should be adopted
to minimize the overtopping and to provide good shelter, on the contrary,
this involves higher investment as well as it affects the aesthetics. As the