Contents
xi
4. Coastal Erosion and Protection Measures
Including Case Studies
97
4.1 Introduction............................................................................
97
4.2 Erosion Process......................................................................
97
4.3 Causes for Coastal Erosion...................................................
98
4.4 Strategy for Coastal Protection.............................................
99
4.5 Coastal Protection Measures................................................ 102
4.5.1 General.......................................................................... 102
4.5.2 Hard measures............................................................. 102
4.5.2.1 Hard structures.......................................... 103
4.5.2.2 Soft structures............................................. 111
4.5.3 Soft measures............................................................. 114
4.5.3.1 Beach nourishment................................... 114
4.5.3.2 Placement of sand and borrow site ... 116
4.5.3.3 Methods...................................................... 116
4.5.3.4 Végétation cover......................................... 118
4.6 Case Studies............................................................................. 119
4.6.1 Concept génération.................................................... 119
4.6.2 Tamil Nadu (groin field).......................................... 121
4.6.2.1 North of Chennai Harbour
(transitional groin field) ......... 121
4.6.2.2 Vaan Island (submerged artificial
reefs)............................................ 124
4.6.3 Kérala coast................................................................ 128
4.6.3.1 General......................................................... 128
4.6.3.2 Behaviour of seawalls prior
to and after 2008 ...................... 130
4.6.3.3 Failure of seawalls...................................... 132
4.6.3.4 Behaviour of groin fields.......................... 134
4.6.3.5 Artificial beach nourishment................... 137
4.6.3.6 Geosynthetic products as Coastal
protection measure................... 139
4.7 Assessment of Hard and Soft Measures............................. 142
4.8 Tidal Inlets................................................................................ 143
4.8.1 General.......................................................................... 143
4.8.2 Tidal flushing............................................................. 144
4.8.3 Stability of an inlet.................................................... 145
4.8.4 Stabilisation of tidal inlets....................................... 147