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Concept
Storm surge
Summary
A storm surge, storm flood, tidal surge, or storm tide is a coastal flood or tsunami-like phenomenon of rising water commonly associated with low-pressure weather systems, such as cyclones. It is measured as the rise in water level above the normal tidal level, and does not include waves.
The main meteorological factor contributing to a storm surge is high-speed wind pushing water towards the coast over a long fetch. Other factors affecting storm surge severity include the shallowness and orientation of the water body in the storm path, the timing of tides, and the atmospheric pressure drop due to the storm. There is a suggestion that climate change may be increasing the hazard of storm surges.
Some theorize that as extreme weather becomes more intense and sea level rises due to climate change, storm surge is expected to cause more risk to coastal populations. Communities and governments can adapt by building hard infrastructure, like surge barriers, soft infrastructure, like coastal dunes or mangroves, improving coastal construction practices and building social strategies such as early warning, education and evacuation plans.
At least five processes can be involved in altering tide levels during storms.
Wind stresses cause a phenomenon referred to as wind setup, which is the tendency for water levels to increase at the downwind shore and to decrease at the upwind shore. Intuitively, this is caused by the storm blowing the water toward one side of the basin in the direction of its winds. Strong surface winds cause surface currents at a 45° angle to the wind direction, by an effect known as the Ekman spiral. Because the Ekman Spiral effects spread vertically through the water, the effect is proportional to depth. The surge will be driven into bays in the same way as the astronomical tide.
The pressure effects of a tropical cyclone will cause the water level in the open ocean to rise in regions of low atmospheric pressure and fall in regions of high atmospheric pressure.
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Ontological neighbourhood
Related concepts (21)
Thames Barrier
The Thames Barrier is a retractable barrier system built to protect the floodplain of most of Greater London from exceptionally high tides and storm surges moving up from the North Sea. It has been operational since 1982. When needed, it is closed (raised) during high tide; at low tide, it can be opened to restore the river's flow towards the sea. Built about east of the Isle of Dogs, its northern bank is in Silvertown in the London Borough of Newham and its southern bank is in the New Charlton area of the Royal Borough of Greenwich.
Tropical cyclone
A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depending on its location and strength, a tropical cyclone is referred to by different names, including hurricane (ˈhʌrᵻkən,_-keɪn), typhoon (taɪ'fuːn), tropical storm, cyclonic storm, tropical depression, or simply cyclone.
Lake Pontchartrain
Lake Pontchartrain (ˈpɒntʃətreɪn ) is an estuary located in southeastern Louisiana in the United States. It covers an area of with an average depth of . Some shipping channels are kept deeper through dredging. It is roughly oval in shape, about from west to east and from south to north. In descending order of area, the lake is located in parts of six Louisiana parishes: St. Tammany, Orleans, Jefferson, St. John the Baptist, St. Charles, and Tangipahoa. The water boundaries were defined in 1979 (see list of parishes in Louisiana).