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CDM - Storm Surges & Erosion
Storm Surges & Erosion

What is a Storm Surge?

A Storm Surge is an abnormal rise of water created by a storm, which is over and above the predicted tides. This water is pushed towards the shore by the force of the winds which come from the storm. This water piles up and creates an elevated water level called the storm surge.

This surge combines with the normal high tide and creates something called a storm tide. This combination, in particular, causes extreme flooding in coastal areas. Storm tides can reach up to 20 feet or more and they damage roads, homes, erode beaches and endanger human lives.

How powerful will a Storm Surge be?

A number of factors influence just how powerful a storm surge is. It depends on features of the storm, like its size, when it hits, wind intensity and the direction it’s coming from. Other factors like the shape and characteristics of the coastline can also influence the surge’s power.

Every land mass has some land that extends out into the ocean, sloping downward. It looks like a shelf, and that’s why this submerged land is known as the continental shelf. The width and slope of this continental shelf also impact the power of the storm surge. A shallow slope has the potential to produce a greater storm surge than a steep one.


Storm Surges can be the most devastating and notable effect from a hurricane. They are estimated to be responsible for 90 percent of all hurricane related deaths worldwide. Areas of low elevation along the coast are at the highest risk for storm surge impacts.

Many buildings withstand hurricane force winds only to have their foundations stripped away by a storm surge. Adding to the destructive power of surge are battering waves. Water weighs approximately 1,700 pounds per cubic yard and if these waves beat against a structure for an extended period of time, they can demolish anything that isn’t built to handle such force.

A storm surge may also cause:

  • Beach erosion
  • Destruction of buildings, roads, utility poles and pipes
  • Loss of life (human, animals and marine)
  • Water damage to buildings
  • Flooding

Protecting yourself from Storm Surges

These are some natural barriers that can act as protection from Storm Surges:

  • Off shore barrier islands and coral reefs can reduce the power of storm surges. Coral reefs reduce the distance between the bottom of the sea and the top of the wave. The shallow water slows the surge of water, reducing its amplitude at the shore.
  • Mangrove forests near to the shore. The branches slow the flow of water.
  • Forests just inland of the beach. Many areas have extensive forests in the low flatlands just inshore of the beach that reduce water speed and reduce the height of waves and storm surge.

Unfortunately, coastal development has destroyed many of these barriers. Without them, what you can do is move to an area further away from the ocean. If you don’t want to move, or if you can’t, then you must always be aware of storm warnings. If you are told to evacuate – listen!



October 2008


St. Vincent and the Grenadines


Storm surges from hurricane Omar severely damaged the western coast of St. Vincent and the Grenadines. There was widespread flooding, significant erosion and many coastal properties and businesses were destroyed. The Cruise Ship Terminal building received significant damage and all the businesses that are housed there had to be evacuated. Another 20 shops that were housed in the Bus Terminal were destroyed from this storm surge and several others had to be evacuated.

The waters also damaged some vehicles and flooded several houses and one school. Approximately ten fishing boats were destroyed and several reportedly received significant damage.

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