Author(s): Robert Bell
Linked Author(s):
Keywords: Tides; Storm tide; Storm surge; Sea-level rise; Climate change
Abstract: Defining Mean High Water Spring (MHWS) and its intersection with the land continues to be subjective when used to “anchor” coastal hazard zones or delineate the landward jurisdictional boundary of the coastal marine area. Given short sea-level records, similar subjectivity can also occur when combining upper-tide marks and storm surges for coastal engineering projects or for setting minimum ground or building floor levels. By analyzing the anatomy of extreme storm-tide levels at a few New Zealand locations, it is clear that generally high perigean-spring tides dominate storm-tide levels. Finally, the effect of sea-level rise on high-tide exceedances will be proportionately greater on coastal margins subject to small tide ranges. This paper explores these inter-connected links on the role of perigean-spring high tides drawing on examples from New Zealand and Pacific Island countries. High-tide exceedance nomographs provide a pragmatic approach to making long-term decisions on the appropriate placement of the land/sea boundary, now and into the future, by inclusion of sea-level rise.
Year: 2010