Application of Regional Climate Models for Coastal Design Parameters along India

Bhat, S.; Jain, P., and Deo, M.C., 2019. Application of regional climate models for coastal design parameters along India. Journal of Coastal Research, 35(1), 110–121. Coconut Creek (Florida), ISSN 0749-0208. Coastal structures are generally designed on the basis of significant wave height, Hs2, corresponding to a return period of 100 years. This design wave height is derived by fitting an appropriate statistical distribution to a set of long-duration Hs data, either observed or simulated, using historical wind conditions. This study investigates what might happen if wind conditions projected on the basis of regional climate models (RCMs), reflecting the effect of climate change, are instead used. At a series of 91 coastal stations spread over the entire 7000-km-long coastline of India, waves were simulated for two time slices of 27 years each in the past and future using a numerical wave model driven by an ensemble of RCMs. The RCMs were earlier run for a moderate global warming scenario. The long-term statistical analysis of resulting wave data was carried out, and Hs with a 100-year return period were derived at each location. It was noticed that if projected wind were used in the place of past wind, an increase in the magnitude of design Hs is likely to be encountered at most stations, although there might be some locations where a decrease instead of an increase might happen. Because the west coast is subjected to different wind conditions than the east coast, it also showed different behavior in terms of the change. These observations were supported by comparative analysis of trends, probability distributions, and wave rose diagrams of past and projected wave data.