Tide-surge interaction and its role in the distribution of surge residuals in the North Sea

[1] Storm surges are the sea level response to meteorological conditions. Scientists and engineers need to understand the interaction of surges with the tide in order to provide better estimates of extreme sea level for use in coastal defense. Using data from five tide gauges, spaced equally along the North Sea coastline around the UK, we show that the mode of peak residual occurrence is everywhere 3 to 5 hours before the nearest high water. We reveal a previously unobserved mode that falls 1 to 2 hours prior to high water, although this cluster is not associated with the highest residuals. A simple mathematical explanation for surge clustering on the rising tide is presented. The phase shift of the tidal signal is combined with the modulation of surge production due to water depth in a model that provides a good description of the residual data set. The results contain several features of interest for flood risk management. We show that large, locally generated surges are precluded close to high water. For physically realistic arrival times of any travelling surge component, the residual peak will avoid high water for any finite tidal phase shift. Furthermore, increasing the tidal range reduces the risk of residual peaks near high water. We draw attention to the existence of critical time and space scales for surge development and decay. For reliable operational forecasts of sea level, coastal numerical models need to reproduce both tides and surges with improved accuracy.

[1]  H. Ritchie,et al.  Forecasting Storm Surges Along the East Coast of Canada and Northeastern US: The Storm of 21 January, 2000 , 2004 .

[2]  D. Pugh,et al.  Coastal sea level prediction for climate change , 1999 .

[3]  D. Prandle.  Storm surges in the southern North Sea and River Thames , 1975, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[4]  J. Proudman.  Oscillations of tide and surge in an estuary of finite length , 1957, Journal of Fluid Mechanics.

[5]  H. Ritchie,et al.  Forecasting storm surges along the east coast of Canada and the North‐Eastern United States: The storm of 21 January 2000 , 2006 .

[6]  Sarah Lavery,et al.  Flood risk management in the Thames Estuary looking ahead 100 years , 2005, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[7]  J. O'Brien,et al.  Remote forcing contribution to storm‐induced sea level rise during Hurricane Dennis , 2006 .

[8]  J. Vassie,et al.  APPLICATIONS OF THE JOINT PROBABILITY METHOD FOR EXTREME SEA LEVEL COMPUTATIONS. , 1980 .

[9]  Walter H. F. Smith,et al.  New, improved version of generic mapping tools released , 1998 .

[10]  G. Hubbert,et al.  A numerical modelling study of storm surges in Bass Strait , 2003 .

[11]  Bruce C. Douglas,et al.  Twentieth-Century Storm Activity along the U.S. East Coast , 2000 .

[12]  R. Flather,et al.  Existing operational oceanography , 2000 .

[13]  N. Bernier,et al.  Predicting the frequency of storm surges and extreme sea levels in the northwest Atlantic , 2006 .

[14]  P. Woodworth,et al.  Evidence for Systematic Changes in Extreme High Waters since the Mid-1970s , 2004 .

[15]  J. Wolf,et al.  The interaction of surge and tide in the North Sea and River Thames , 1978 .

[16]  J. F. Keers.  An empirical investigation of interaction between storm surge and astronomical tide on the east coast of Great Britain , 1968 .

[17]  E. Gumbel,et al.  EXTREME SEA LEVELS; THE JOINT PROBABILITIES METHOD REVISITED AND REVISED. , 1989 .

[18]  J. Proudman.  The propagation of tide and surge in an estuary , 1955, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[19]  Allan McRobie,et al.  The Big Flood: North Sea storm surge , 2005, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[20]  C. Pattiaratchi.  Tides, surges and mean sea-level: a handbook for engineers and scientists , 1988 .

[21]  D. Pugh.  Tides, Surges and Mean Sea-Level , 1987 .

[22]  N. Heaps,et al.  Storm surges, 1967–1982 , 1983 .

[23]  D. Cartwright,et al.  A unified analysis of tides and surges round North and East Britain , 1968, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[24]  J. Rossiter.  Interaction Between Tide and Surge in the Thames , 1961 .