Functional performance of coastal protection structures

Abstract

Coastal protection and other structures often end up damaging coastal morphology and ecosystems that provide natural protection to the coast. Out of India's 78 km long southwest coast, under consideration, 25.50 km has seawalls. There are 49 groins and a few harbor breakwaters. It also has a submerged artificial reef and bio shield as coastal protection measures. Multi-dated satellite images and topographical maps were used to analyze the historical changes. Problem-specific field studies were conducted to understand the current status and impacts of these structures on coastal morphology, impact on the adjacent shoreline, structural failures leading to 'no protection' despite protection structures in place, and the impacts on the livelihood of the coastal community. This enabled the assessment of the functional performance of these protection measures. Hard structures for coastal protection are either rubble mound seawalls, groins or a combination of both. All these hard structures could not protect the coast the way it was expected. The frequent overtopping of high waves causing flooding on the landward side has emerged as a significant new concern. Performance of submerged artificial reefs was also below expectation. Bio shields survived only in stretches where beaches are stable beaches. Analysis of the structural performance of the protection measures is warranted to understand the exact reasons for the poor functional performance of coastal protection measures.