The surge phenomenon is a temporary and local elevation of the sea level along the coast. Most of the time this phenomenon is caused by weather conditions (atmospheric depression, wind, storm, etc.) and sometimes by earthquakes (tsunami).
This increase in sea level can, especially if combined with a high tide, favour the passage of water above protective works and cause flooding in coastal areas.
The surge provoked by Hurricane Ike resulted in the flooding of Bolivar, Texas (USA). © US Air Force / First class sergeant Wally Bacio, public domain