Smarter Than a 5th Grader?

August 12, 2010 Thursday

Last week I wrote urging teachers to discuss how geography can influence natural disasters with their students. I used the example of how the slope of a continental shelf can influence the magnitude of a storm surge. I received a phone call shortly after posting the blog from a friend asking me, "Please explain more about a storm surge so I can be smarter than my 5th grader."

So here is a little more information to help all the struggling parents/grandparents stay ahead of their children. A storm surge is simply water being pushed ashore by the fierce winds which accompany a major storm system (usually a hurricane). The difference in a storm surge and a tsunami is the force responsible for the water coming ashore. If the causing force comes from below the water, an underwater earthquake or volcanic eruption, it will be a tsunami. However if the causative factor comes from above the water, a hurricane or cyclone, it will be a storm surge.

What geographical features can make a storm surge more dangerous? The level of the land above sea level is a critical factor. If your house is located only a few feet above sea level it doesn't take much water to flood it. The Gulf Coast and Atlantic coastlines of the United States are densely populated areas situated an average of only 10 feet above sea level.

Another important factor in the height of the storm surge is the continental shelf slope off shore. If there is a shallow shelf leading up to the land the surge will be bigger because there is nowhere else for the water to go. The coming wave will have to keep growing up (since downward growth is not a possibility) until it hits land. A steep off shore continental shelf is able to contain the water and diminish the surge which comes ashore.

Just to make things a little more complicated you must remember to factor in the time when a storm surge is likely to occur. A surge combined with high tides results in more water. A low tide and a storm surge will produce less water.

Well that is enough of a geography lesson for one day. Remember that you asked me for the information. On the bright side, I am certain that you are now smarter than a 5th grader.

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