97
Chapter 4
Coastal Erosion and Protection Measures
Including Case Studies
t
4.1 Introduction
Erosion is said to occur along a coast when the quantity of loss of sédiments
surpasses the quantity supplied to it. Any beach is supposed to be in equilibrium, when the sédiment movement for a period of a few years is considered. However, some beaches expérience excessive érosion or advancement
of shoreline disturbing the equilibrium which is the résultant of wave climate and morphology and is location spécifie.
Coastal érosion is a common problem along the coasts around the globe
calling for its protection that include cultivate lands, valuable properties,
power plants, tourist attractions, etc. The érosion resulting in the loss of
beaches and significant portion of the shoreline is common during storms,
cyclones and tsunami. The loss of beach material along the shore is usually sudden and devastating. Apart from the said causes due to the said
extreme events that would last only for a few days, the perennial érosion
along a coast would be due to natural and manmade or a combination of
both. In this case, Coastal érosion can also be graduai process over years
even without any intervention through structures. The causes for érosion
need to be thoroughly examined prior to the proposai of a solution or a protection measure. The manmade causes would be due to the construction of
structures like breakwaters for development harbours, or shore connected
solid or rubble mound structures jetting into the sea that are installed for
either drawing sea water into land for aquaculture, power plants, etc., the
effects of which are known priori if careful modeling of sédiment and wave
dynamics is carried out in the planning stage.
4.2 Erosion Process
The wave that generates in the offshore propagates towards the coast experiencing the phenomena of shoaling, refraction, diffraction and combined
Chapter 4
Coastal Erosion and Protection Measures
Including Case Studies
t
4.1 Introduction
Erosion is said to occur along a coast when the quantity of loss of sédiments
surpasses the quantity supplied to it. Any beach is supposed to be in equilibrium, when the sédiment movement for a period of a few years is considered. However, some beaches expérience excessive érosion or advancement
of shoreline disturbing the equilibrium which is the résultant of wave climate and morphology and is location spécifie.
Coastal érosion is a common problem along the coasts around the globe
calling for its protection that include cultivate lands, valuable properties,
power plants, tourist attractions, etc. The érosion resulting in the loss of
beaches and significant portion of the shoreline is common during storms,
cyclones and tsunami. The loss of beach material along the shore is usually sudden and devastating. Apart from the said causes due to the said
extreme events that would last only for a few days, the perennial érosion
along a coast would be due to natural and manmade or a combination of
both. In this case, Coastal érosion can also be graduai process over years
even without any intervention through structures. The causes for érosion
need to be thoroughly examined prior to the proposai of a solution or a protection measure. The manmade causes would be due to the construction of
structures like breakwaters for development harbours, or shore connected
solid or rubble mound structures jetting into the sea that are installed for
either drawing sea water into land for aquaculture, power plants, etc., the
effects of which are known priori if careful modeling of sédiment and wave
dynamics is carried out in the planning stage.
4.2 Erosion Process
The wave that generates in the offshore propagates towards the coast experiencing the phenomena of shoaling, refraction, diffraction and combined