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What is a storm surge?
Of all the hazards caused by hurricanes, storm surges are the greatest threat to coastal lives and property. It can remove houses from their foundations, flood riverside communities miles inland, and destroy sand dunes and dams that normally protect coastal areas from storms.
When a hurricane reaches the coast, it pushes a large amount of seawater ashore. This is what we call storm surge.
As the storm approaches, this surge is manifested as a gradual rise in the water level. Depending on the size and trajectory of the hurricane, storm surge floods can last for several hours. Then it subsided after the storm passed.
The water level during a hurricane can reach 20 feet or more above normal sea level. Above the strong waves, the storm surge of a hurricane can cause catastrophic damage.
What determines the height of the storm surge?
The storm surge started on the high seas. The strong wind of the hurricane pushes the sea around and causes the water to accumulate under the storm. The low air pressure of the storm also played a small role in raising the water level. The height and extent of this pile of water depend on the intensity and size of the hurricane.
As the pile of water moves toward the coast, other factors will change its height and range.
this Seafloor depth Is a factor.
If the seabed of a coastal area slopes slowly away from the coastline, it is more likely to see a higher storm surge than a steeply descending area. The gentle slopes of the coasts of Louisiana and Texas caused some devastating storm surges. The surge of Hurricane Katrina in 2005 broke the dam and flooded New Orleans.Hurricane Ike Storm surge of 15 to 17 feet In 2008, waves swept hundreds of houses near the Bolivar Peninsula in Texas. Both of these were large and powerful storms that hit vulnerable areas.
The shape of the coastline can also shape the waves. When the storm surge enters the bay or river, the geographic location of this land is like a funnel, pushing the water level higher.
Other factors contributing to storm surge
Ocean tides caused by the gravity of the moon and the sun can also increase or decrease the impact of storm surges. Therefore, it is very important to know the time of local tides compared to hurricanes making landfall.
At high tide, the water level has risen. If the landfall occurs at high tide, the storm surge will cause higher water levels and bring more water further inland. When Hurricane Isaias hit North Carolina near its climax on August 3, 2020, Carolina saw these effects. Isaias brought about Myrtle Beach 4 feet, South Carolina, but the water level is More than 10 feet Exceed the normal level.
Sea-level rise It is another increasingly serious problem affecting storm surges.
As the water warms, It expands, In the past century, sea levels have risen slowly because of Global temperature riseThe fresh water produced by melting ice caps and glaciers has also exacerbated sea level rise.They are together Increase the height of the background oceanWhen a hurricane arrives, a higher ocean means that the storm surge can carry water farther inland, which can have a more dangerous and wider impact.