Author(s): Talpe Liyanage Chanaka Vinodh; Norio Tanaka
Linked Author(s): Norio Tanaka
Keywords: No Keywords
Abstract: The 2004 Indian Ocean tsunami (IOT) and the 2011 Great East Japan tsunami (GEJT) emphasize the importance of Ecosystem-based Disaster Risk Reduction (Eco-DRR) to minimize the impact of future tsunamis, to protect the living community, environment and infrastructure. In a coastal lagoon system, apart from vegetation impact, the physical characteristics of lagoon play a key role in tsunami mitigation. The laboratory experiments were conducted to understand how a tsunami like solitary wave propagates in one horizontal dimension against the effects of beach slope, sand dune height and length of lagoon in cross-shore direction. The wave height to depth ratios of 0.1 to 0.4 were used. The resultant maximum runup for beach slope of 1:30 and 1:7, and wave transmission height were measured using a slope of 1:4 at landward of lagoon. The plunging breaking, surging breaking and nonbreaking type of waves were observed on the beach slope with the change of wave height to depth ratios. The undular bores and breaking bores were observed inside of lagoon with the change in wave transmission height to lagoon depth ratios. The dimensional analysis was used to compare the maximum runup effect. Thus, a coastal lagoon having larger sand dune and larger length in cross-shore distance help to increase more resilience against tsunami attack and should be considered in effective coastal ecosystem planning.