Floods are not only the latest news story that we see on the television, but are also a part of the heritage of the entire human race. Every culture has mythic stories of the ancient times when deluges covered the whole earth as a divine punishment. The English word ‘flood’ has changed only slightly in spelling and pronunciation since its Latin root ‘fluctus’ and its intermediate linguistic ancestors like the Dutch ‘vloed’ and the German ‘flut.’
Ocean tides are a natural flood that happen every month. Floods in general may be considered the most natural of all natural disasters. Water always flows to the lowest point of any local geography and, when human habitation happens to have been built in those low places, we call it a disaster. Perhaps flooding pinpoints a significant characteristic about human behavior. We like living near water and are willing to pay the price of an occasional disruption in our lives in order to enjoy the benefits of living on the seashore or on the banks of a river. Commerce often depends on easy access to navigable waters, but such infrastructure can easily and rapidly be overwhelmed by flood waters.
The ocean can flood the shore, a river can overflow its banks, a lake can rise beyond its normal boundaries or the man-made barriers holding back any of these bodies of water can collapse and allow flooding to occur. Even tunnels and transport networks can be affected. Abnormal amounts of rain or the melting of excessive snow pack far upstream will add to the volume of water in downstream lakes, rivers and ponds. The effect on those of us who live and work in those areas depends a great deal on the preventive measures we will have taken beforehand.
Permanent preparations for flooding in areas known to be susceptible can range from levees and overflow reservoirs to stockpiling of materials for sandbag barriers. The Netherlands is an area of the world best know for actually creating new land by expanding its flood control measures of dikes, pumps and channels. Artificial barrier islands and beach nourishment are being tried out on the Atlantic coast of the United States to control coastal flooding. Venice has constructed one of the world’s most involved and enormous flood control mechanisms with seabed gates that rise and fall in an opposing cycle to the tides of the Adriatic.