Design Storm Surge Level Estimation for Port and Harbor Facilities

Kumar, D.-S.; Behera, M. R.; Nadella, S., and Kumar, A. -V., 2024. Design storm surge level estimation for port and harbor facilities. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 1064-1069. Charlotte (North Carolina), ISSN 0749-0208. Strategic coastal facilities like ports and harbors, sensitive coastal infrastructures are vulnerable to inundation induced by storm surges. The ground level of such facilities is designed considering the highest surge level possible at the site called Probable Maximum Storm Surge (PMSS). Extreme Value Analysis (EVA) has been applied for PMSS studies to evaluate 100-year return period surge levels from historical data. The EVA based PMSS values do not consider the dynamic conditions that affect surge level like orientation of the coastline with the cyclone track, cyclone intensity, size and speed of the storm; and local bathymetry. Further, it does not account for the non-linear interactions of storm surges with surface gravity waves that induces wave setup. Therefore, a modelling framework capable of capturing the dynamic surge characteristics is required to provide accurate PMSS estimates for a site. The methodology suggested in this study applies ocean circulation model ADCIRC (ADvanced CIRCulation) coupled with nearshore wave model namely SWAN (Simulating WAves Nearshore) to evaluate PMSS. The models are validated against cyclone Tauktae event and then applied for evaluating the PMSS of ports Sakhari Nate and Harnai along the west coast of India. The PMSS is simulated by using the available cyclone track of Tauktae where the cyclone parameters (namely, pressure deficiency at the centre and maximum sustained wind speed) were replaced with hypothetical storm parameters. The results showed that wave setup component brought in by coupling ADCIRC with SWAN increased the final estimates significantly. The PMSS obtained from the simulations for Harnai and Sakhari Nate was found to be 1.98m and 1.99m, respectively. The methodology discussed in this study is a vital asset for setting design standards of strategic coastal infrastructures.