When meteorological conditions give rise to strong winds, higher water levels than those at normal high tide are produced – this is a tidal surge, or storm surge. The North Sea and east coast of Britain is particularly affected by tidal surges.
Depressions play a part in influencing tidal surges. A depression is an intense low-pressure weather system. Over the North Sea particularly, they produce low pressure conditions, which raise sea levels. For every one millibar drop in pressure, there can be a 1cm rise in sea level. Winds drive the waves towards the coastline – water piles up at the coast. High tides can amplify can amplify the effects of depressions on sea level.
North Sea Tidal Surge of 1953
Spring tides were in action anyway, meaning tides were already quite high. Effects were intensified when and Atlantic depression passed down to the North Sea. On the Westerly side of the depression, northerly gales forced sea water in a southerly direction at high tide. This resulted in a tidal surge exceeding 5m above the mean sea level of the area. The large waves damaged coastal defences around East Anglia. 307 people in England died as a result of the tidal surge.