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Coastal Engineering: Theory and Practice
Fig. 4.28(e) A view of wave action on the seawall during monsoon.
4.7 Assessment of Hard and Soft Measures
Hard Engineering Measures
Structural performance — Coastal defense structures are usually
designed for 30- or 50-year design life with minimum or no maintenance
at ail. The weight of individual units and the thickness of various layers
are given as per the provisions mentioned in the shore protection manual.
During an extreme storm event the head section of the structures are more
susceptible to damage which can be regulated and restored upon consistent
maintenance checks.
Overall performance — These structures serves their intended purposes
very well. The effect of érosion was successfully overthrown and beach formation was achieved. The heavy mound structures reflect the impact wave
energy incident on them and dissipate it leaving minimal impact on the
coast, thereby reducing excessive érosion.
A standing example is the groin field at Royapuram. A five decade long
problem of érosion due to construction of breakwater for the formation of
Chennai port was resorted after careful study and implémentation of the
groin field.