116
Coastal Engineering: Theory and Practice
of a slightly steeper profile, whereas, fine sands are easily suspended and
relocated.
(c) Shore face
Shore face nourishment is the supply of sand to the lower part of the beach,
especially on the sea side of an existing bar. This measure is most suited
for régions with long term sédiment deficiency or in areas where coastal
protection schemes are implemented. Shore face and beach nourishment
can be coupled to yield strengthened coastal profile.
4.5.3.2 Placement of sand and borrow site
• The sand could be dumped in the affected area to take the natural profile.
The dredged spoil is discharged inshore through a split hopper dredger or
directly pumping directly over to the beach through pipelines. Though,
the distribution of size of the sédiment and its influence in the beach nourishment was suggested by few researchers, including Shore Protection
Method. Sands on the updrift side, that are intercepted by nature (river
mouths, approach channels, etc.) or man-made structures, from nearby
estuaries, lagoons, backwaters, inlets can serve as sources for beach nourishment. The main drawbacks are:
• Once placed on the beach, the quality of the beach dépends on the quality
of sand adopted for nourishment which is often not fulfilled.
• Source for quality sand become quite difRcult at certain locations. Continuons exploitation of the source would lead to déplétion.
• Dredging of sand is not eco-friendly to eco-system in particular to marine
life like the sea turtles.
• It is cost intensive and involves regular maintenance. For instance, the
pumps are designed with a certain handling capacity. During the monsoon, when the sédiments to handle are significant, power failure would
be a drawback. At this instance, dredging would be suspended leading
to a steep cumulative increase in the quantity to be dredged. This needs
careful attention.
4.5.3.3 Methods
There are two major design methods for the design of the beach nourishment, one is mathematical érosion model, which works only in case érosion
is clearly caused by a gradient in long shore transport. The uncertainties
in this method are quite high.
Coastal Engineering: Theory and Practice
of a slightly steeper profile, whereas, fine sands are easily suspended and
relocated.
(c) Shore face
Shore face nourishment is the supply of sand to the lower part of the beach,
especially on the sea side of an existing bar. This measure is most suited
for régions with long term sédiment deficiency or in areas where coastal
protection schemes are implemented. Shore face and beach nourishment
can be coupled to yield strengthened coastal profile.
4.5.3.2 Placement of sand and borrow site
• The sand could be dumped in the affected area to take the natural profile.
The dredged spoil is discharged inshore through a split hopper dredger or
directly pumping directly over to the beach through pipelines. Though,
the distribution of size of the sédiment and its influence in the beach nourishment was suggested by few researchers, including Shore Protection
Method. Sands on the updrift side, that are intercepted by nature (river
mouths, approach channels, etc.) or man-made structures, from nearby
estuaries, lagoons, backwaters, inlets can serve as sources for beach nourishment. The main drawbacks are:
• Once placed on the beach, the quality of the beach dépends on the quality
of sand adopted for nourishment which is often not fulfilled.
• Source for quality sand become quite difRcult at certain locations. Continuons exploitation of the source would lead to déplétion.
• Dredging of sand is not eco-friendly to eco-system in particular to marine
life like the sea turtles.
• It is cost intensive and involves regular maintenance. For instance, the
pumps are designed with a certain handling capacity. During the monsoon, when the sédiments to handle are significant, power failure would
be a drawback. At this instance, dredging would be suspended leading
to a steep cumulative increase in the quantity to be dredged. This needs
careful attention.
4.5.3.3 Methods
There are two major design methods for the design of the beach nourishment, one is mathematical érosion model, which works only in case érosion
is clearly caused by a gradient in long shore transport. The uncertainties
in this method are quite high.