Deconstructing a jetty to rectify the downdrift erosion
2020
Saengsupavanich, Cherdvong
A jetty is a coastal structure constructed across the surf zone to prevent sediment deposition at a river mouth. It creates updrift accumulation and downdrift erosion. Deconstructing the jetty may restore the situation but create another problem. This study used the Cha-am beach in Thailand to simulate future shoreline positions under different scenarios. The main tool used in the study was the software package LITPACK. The calibrated simulations showed that, if no action was taken, the updrift part of the beach would be widened by as much as 130 m in 25 years but the downdrift side of the jetty would experience severe coastal erosion. Deconstructing the jetty would alternate the outcome. The area where the erosion was foreseen along the downdrift shoreline would not occur anymore. The sediment once intercepted by the jetty would move to pass the inlet. However, the updrift shoreline would adjust its alignment, eroding existing houses and other buildings. While jetty deconstruction would restore the downdrift part of the beach, it would at the same time destroy some properties along the updrift section. Removing the jetty may experience great social resistance. Decisionmakers should be equipped with adequate information and coastal engineering can provide some necessary inputs.
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