Towards Implementing Water Level Variations into Coastal Vulnerability Indexes in Microtidal Seas

Soomere, T.; Bagdanavičiūtė, I.; Barzehkar, M., and Parnell, K.E., 2024. Towards implementing water level variations into coastal vulnerability indexes in microtidal seas. 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. 48-52. Charlotte (North Carolina), ISSN 0749-0208. We explore the potential of several quantities that reflect the magnitude of local water level variations to characterize the contribution of water level into estimates of the Coastal Vulnerability Index (CVI) in microtidal seas hosting substantial water level variations. The analysis is based on sea level time series reconstructed with the Rossby Centre Ocean model for 1961–2005 and an early version of the RCA4-NEMO model for 1961–2009. The projections of extremely high and low sea levels for return periods of 10 and 50 yrs are constructed using sea level extremes in 12 month long time intervals, block maximum method and several extreme value distributions. The focus is on the relatively straight Baltic proper shore of Lithuania. We show that projected extremely high and low sea levels once in 10 and 50 yrs provide certain independent information about vulnerability along this coastal segment. The use of a larger number of parameters shrinks the range of the output values of the CVI. The outcome provides important input for coastal management but also suggests that more elaborated quantities might better characterize the impact of varying water levels on coastal vulnerability.