What is a Storm Surge? All you need to know about its causes and impact

Of all hurricane deaths recorded, about 90% occur due to flooding and tropical cyclones. And half of the 90% die due to the storm surge.

What is a storm surge?

The National Ocean and Atmospheric Administration (NOAA) defines a storm surge as an abnormal rise in water levels propelled by a storm.
A storm surge is also one of the two reasons for a storm tide, which results in colossal tides with heights of 20 feet and more. Moreover, the NOAA states that a storm surge is the greatest threat to life and property from hurricanes.

Typhoon Haiyan in 2013 is one of the current examples of a devastating storm surge.




The tropical storm had hit the Philippines, causing a storm surge of 7.5 meters, which resulted in at least 7,000 deaths in the coastal regions.

The destruction of life happened even after consistent coastal flood warnings because the people failed to gauge the magnitude of the storm surge.

What causes a storm surge?

Strong winds are the primary instigators of a surge storm, caused by swirling winds that push seawater toward the shore. Wind swirls also push the water into a mound at the centre of the storm, and the water level increases as the wind speed rise. However, storm surges are a complex phenomenon that multiple factors may impact.

Some of these factors are listed below:

• The intensity of the wind speeds
• Low air pressure in the centre of the storm
• Speed of the storm can lead to a broader surge if slow and a strong open coast surge if fast.
• The size of the wind fields, the higher it gets, the bigger would be the storm surge
• The angle of the storm concerning the coastline, with the perpendicular storms causing severe storm surges, whereas parallel ones cause surges

Other factors: local geographical features, width, and curve of the continental shelf

FAQs

What causes a storm surge?
While strong wind storms are the primary reason, a storm surge is impacted by several other factors.

What are a few examples of hurricanes that cause severe storm surges?
Katrina (2005) in the Atlantic Ocean and Haiyan (2013) in the Pacific Ocean are two hurricanes that caused severe storm surges.