4. Coastal Erosion and Protection Measures Including Case Studies
119
wave energy moving onshore; therefore, it protects the shoreline from
érosion. However, its site-specificity means that it may be successful in
estuarine conditions (low energy environment), but not on the open coast
(high energy environment). In some cases, végétation cover fails because
environmental conditions do not favour the growth of species at the particular site or there is ignorance as to how to plant properly given the
same conditions. It is also possible that anthropogenic influences hâve completely altered the natural processes in the area. The most obvious indicator
of site suitability is the presence of végétation already growing. This can be
extended by other factors such as the slope, élévation, tidal range, salinity,
substrate and hydrology [Clark, 1995 and French, 2001].
Mangrove forests are dense plantation that grows in seawater. These
plantations hâve specially adapted root System, which goes deep inside the
water bed. The roots get tangled and almost the trunk the submerged in
water. The roots help in holding the ground intact and prevent soil érosion
due to wave action. Also, due to dense nature, the wave atténuation is very
high. The ability of waves to carry sédiments is proportional to its flow
velocity, which is drastically reduces on incidence with mangrove forests
and facilitâtes sédiment settlement, soil build up and consolidation of land.
4.6 Case Studies
4.6.1 Concept génération
Although, several stretches of the coast around the globe are subjected
to severe érosion leading to instability in the shoreline, the two maritime
States of India, namely Tamil Nadu and Kérala that hâve been experiencing
perennial érosion as well as suffered severe damage during the great Indian
Océan tsunami of 2004 are considered herein for case studies. In order to
protect a few stretches vulnérable coast from severe érosion, hard measures
such as seawall and groin field are proposed and, many of them hâve been
executed. The planning of the protection scheme commenced from reconnaissance survey from identification of the vulnérable stretches as well as
those affected during extreme events like a cyclone to field monitoring of
beach profile, bathymetry up to twice surf zone width and sédiment characteristics. Further, the environmental forcing such as wave and current
which drive the sédiments had to be collected and evaluated near shore.
With the predicted the mean breaker height, breaker wave angle, surf width
and net drift magnitude the design of protection layout were finalised. The
proposed shore protection structures are subjected to numerical shoreline
119
wave energy moving onshore; therefore, it protects the shoreline from
érosion. However, its site-specificity means that it may be successful in
estuarine conditions (low energy environment), but not on the open coast
(high energy environment). In some cases, végétation cover fails because
environmental conditions do not favour the growth of species at the particular site or there is ignorance as to how to plant properly given the
same conditions. It is also possible that anthropogenic influences hâve completely altered the natural processes in the area. The most obvious indicator
of site suitability is the presence of végétation already growing. This can be
extended by other factors such as the slope, élévation, tidal range, salinity,
substrate and hydrology [Clark, 1995 and French, 2001].
Mangrove forests are dense plantation that grows in seawater. These
plantations hâve specially adapted root System, which goes deep inside the
water bed. The roots get tangled and almost the trunk the submerged in
water. The roots help in holding the ground intact and prevent soil érosion
due to wave action. Also, due to dense nature, the wave atténuation is very
high. The ability of waves to carry sédiments is proportional to its flow
velocity, which is drastically reduces on incidence with mangrove forests
and facilitâtes sédiment settlement, soil build up and consolidation of land.
4.6 Case Studies
4.6.1 Concept génération
Although, several stretches of the coast around the globe are subjected
to severe érosion leading to instability in the shoreline, the two maritime
States of India, namely Tamil Nadu and Kérala that hâve been experiencing
perennial érosion as well as suffered severe damage during the great Indian
Océan tsunami of 2004 are considered herein for case studies. In order to
protect a few stretches vulnérable coast from severe érosion, hard measures
such as seawall and groin field are proposed and, many of them hâve been
executed. The planning of the protection scheme commenced from reconnaissance survey from identification of the vulnérable stretches as well as
those affected during extreme events like a cyclone to field monitoring of
beach profile, bathymetry up to twice surf zone width and sédiment characteristics. Further, the environmental forcing such as wave and current
which drive the sédiments had to be collected and evaluated near shore.
With the predicted the mean breaker height, breaker wave angle, surf width
and net drift magnitude the design of protection layout were finalised. The
proposed shore protection structures are subjected to numerical shoreline