A storm surge is the unusual rise in sea level usually associated with hurricanes and tropical storms prior to and during landfall. Storm surges are caused primarily by high winds pushing on the ocean surface. This causes the water to pile up higher than the ordinary sea level. Tropical cyclone-induced storm tides can increase the mean water level 5 meters or more. As these winds pass over the surface of the sea they generate waves, which flood the shoreline. The rise in water level and the hammering effect of the waves can cause coastal erosion, flooding, scour roads, undercut sea walls and demolish buildings. Storm Surge is responsible for much of the damage caused by severe weather systems, especially in large, low-lying coastal settlements. According to the US National Weather Service National Hurricane Center, the greatest potential for loss of life related to a hurricane is from storm surge.
You are most at risk from a storm surge if you live close to the coast. A storm surge causes damage in two ways:
- The rising water level floods areas that are usually beyond the water line.
- The breaking waves impact higher along the beachfront and as they crash into the shore, they send water rushing even further inland.
Storm impact is expected to worsen in the future due to increased cyclone activity and heightened storm surges. These surges will, in turn, create more damaging flood conditions in low-lying coastal areas.
Video of how Storm Surge occurs
http://www.nhc.noaa.gov/ssurge/animations/hurricane_stormsurge.swf
What to do if You are at Risk From a Storm Surge
A storm surge is a feature of a hurricane, so take the following general precautions when a hurricane threatens:
- Monitor the radio.
- Wrap important personal items, family documents and electrical appliances in plastic bags and store away from the reach of flood waters.
- Move your refrigerator, stove and furniture to a higher floor, or place them on building blocks and secure to the wall.
- Shut off electrical power, gas and water supplies in areas in immediate danger of flooding.
- Store all chemicals, fertilizers, insecticides, etc., in properly labelled waterproof containers and store away from floodwaters.
- Move small boats to higher ground. Move larger boats and moor in a safe cove.
- Be aware. If you see waves coming in higher than normal tide, be prepared to evacuate.
- Take all necessary flood precautions. (linked to flood page)
Further information
http://www.nhc.noaa.gov/ssurge/ssurge_overview.shtml
http://weready.org/tsunami/index.php?option=com_content&view=article&id=32&Itemid=52