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Section 1: Coastal and fluvial geohazards |
Landslide Section, Disaster Prevention Research Institute, Kyoto University, Uji, Gokasho, Kyoto 611, Japan and Institute of Marine Affairs, Hilltop Lanes, Chaguaramas, Trinidad and Tobago, West Indies
Coastal erosion in Trinidad has caused a loss of land and subsequent damage to many coastal engineering structures. Damage includes roadway failures, loss of agricultural land, coastal flooding and damage to property. In many areas, structural engineering measures have been implemented to prevent these from recurring. An example of erosion and structural measures used in a segment of rapidly eroding coastline along the east coast of the island is presented. The site is part of a coastal section of the largest wetland on the island, the Nariva Swamp, through which drains the largest river system, the Nariva River. Structural measures used include steel sheet piled revetment, steel-reinforced concrete retaining walls, gabion basket retaining structures, boulder splash aprons, a steel-reinforced concrete pile cluster, concrete columns and blocks and boulder riprap. All these an show signs of structural failure, and some have already collapsed. Failures include spelling and cracking of concrete; rebar corrosion; steel pile corrosion; foundation settlement under retaining walls and structures, with subsequent surfical cracking; basal foundation sediment scour and undermining; wave and fluvial induced removal of rip-rap and splash apron boulders, and seasonal burial and sedimentation of the splash apron and concrete pile cluster. Based on this study, it appears that construction-induced high energy conditions and oversight in design and construction were partly responsible for failures.
