Spatial and Temporal Clustering Analysis of Extreme Wave Events around the UK Coastline

Abstract

Densely populated coastal regions are vulnerable to extreme wave events, which can cause loss of life and considerable damage to coastal infrastructure and ecological assets. Here, an event-based analysis approach, across multiple sites, has been used to assess the spatial footprint and temporal clustering of extreme storm-wave events around the coast of the United Kingdom (UK). The correlated spatial and temporal characteristics of wave events are often ignored even though they amplify flood consequences. Waves that exceeded the 1 in 1-year return level were analysed from 18 different buoy records and declustered into distinct storm events. In total, 92 extreme wave events are identified for the period from 2002 (when buoys began to record) to mid-2016. The tracks of the storms of these events were also captured. Six main spatial footprints were identified in terms of extreme wave events occurrence along stretches of coastline. The majority of events were observed between November and March, with large inter-annual differences in the number of events per season associated with the West Europe Pressure Anomaly (WEPA). The 2013/14 storm season was an outlier regarding the number of wave events, their temporal clustering and return levels. The presented spatial and temporal analysis framework for extreme wave events can be applied to any coastal region with sufficient observational data and highlights the importance of developing statistical tools to accurately predict such processes.

Spatial Characteristics and Duration of Extreme Wave Events around the English Coastline

“…The Weibull distribution has been used here for general conformity with many studies [26], although some more recent studies [7,27] use a generalized Pareto distribution (GPD) with the POT data. Caires [26] undertook a comparison of extremes calculation using a 20-year shallow water (19 m) dataset from the Netherlands using five different methods.…”

“…For a long time, studies of storm tides have demonstrated that impacts from coastal processes under extreme conditions vary considerably along coastlines [3][4][5][6], while, more recently, a similar argument was made for the spatial variability of wave extremes and their relevance for the management of coastal hazards [7].…”

“…On a larger scale, Malagon Santos et al [7] considered a multi-site analysis of the UK coastline using return periods calculated from data from 18 buoys, of which seven were deep water locations. In this paper, we follow a similar approach but use a dense network of 40 wave buoys deployed around the English coast, which allows a higher-resolution spatial analysis and highlights some important variations, with consequent beach management and forecasting implications.…”

Coastal Sea Levels, Impacts and Adaptation

“…Three contributions in this Special Issue analyse extreme sea-level changes, including the dynamic wave component. Slangen et al [14] undertake a global assessment of extreme sea-level allowances (i.e., the height a coastal structure needs to be elevated to keep the same frequency and likelihood of sea-level extremes under a certain sea-level rise scenario). Simpson et al [15] and Malagon Santos et al [16] undertake regional assessments of mean and extreme sea levels around Norway and extreme waves around the UK, respectively.…”

“…Slangen et al [14] calculate sea-level allowances at the global scale using the Global Extreme Sea Level Analysis (Version 2) tide gauge database. In particular, they address one of the major uncertainties in future sea-level projections: the contribution of the ice sheets in Greenland and Antarctica to sea-level rise.…”