Flood Created by S.M. Enzler MSc Last update Nov 2006
Floods, flood protection and innovations
| Flooding has caused many casualties in the past, and will continue to do so in the future. Particularly if IPCC expectations of sea level rise and altering climate will prove to be true, we can expect many more floods in all world regions. Floods have different possible causes, such as heavy rainfall, hurricanes and cyclones. Many countries have taken precautions before or after major flooding events, to prevent such events from occurring in the future. On this page, major floods are described, followed by inventions for flood protection. |
Examples of major floods
Flooding occurs all over the world. The examples of major floods mentioned below illustrate this.
The Thames Flood Barrier
London is a city quite susceptible to flooding. This is caused by the continual rise in the water level of the River Thames throughout the years, slow tilting of Britain because ice sheets from the ice age slowly lift land in the North, and the settlement of London on clay beds. Starting in 1974, a flood barrier over the River Thames was built by Woolwich reach. The structure was completed in 1982, and it was officially opened in 1984. After the Oosterscheldekering in The Netherlands, this is now the largest flood barrier in the world. It closes off part of the River Thames from the sea, and when opened ships can pass through it.
In the northern portion of The Netherlands, the IJsselmeer can be found. This large water was called the Zuiderzee in the old days. In the 17th century Hendrik Stevin suggested closing of the Zuiderzee to prevent further breaching of dikes, leading to brackish water entering agricultural land. He suggested pumping the water out of the polders by steam engines, but this idea was not feasible at the time.
In the past 2000 years, The Netherlands has known many flood disasters. The main cause is the low position of the country compared to sea levels. The country owes its name to the fact that more than two-thirds of it lies below sea level. As early as 838, a large area of the north-western Netherlands was flooded by a storm tide. Consequences were severe, because no proper dikes were constructed back than. Large parts of the Dutch coastal area flooded, killing people and animals and destroying many houses. Sources state there may have been as many as 2,500 victims. In 1014 another flood occurred, breaching the coastline and flooding some of the southern islands. Thousands of people died, but an exact number is not known. In the 1400s two floods known as the Saint Elizabeth floods occurred. The first Elizabethan flood led to dike construction and polder creation. A large number of small towns were completely flooded. The second Elizabethan flood was caused by a north-western storm, and water flooding the west passed even the city of Dordrecht. A total of thirty towns were lost, and more than 2,000 people were killed. In 1570 the All Saints flood, the worst flood in The Netherlands so far, occurred. Many dikes collapsed, extremely large sections of coastline were flooded, and eventually almost 5/6 of the entire country was under water. Tens of thousands of people lost their homes, and more than 3,000 people died. Other floods in The Netherlands include the Saint Felix flood in 1530, the Christmas flood in 1717, and the Zuiderzee flood in 1916.
Flood protection: some general measures
Some countries, particularly the US, apply floodplains as a means of flood protection. The principle is relatively simple: parts of land around lakes, rivers or other water bodies are left uncultivated, for as far as the flood approximately ranges. This way, houses in the adjacent land are protected from flooding because it only occurs on the floodplain.
In some cases floods are on their way or have already occurred, and the water force in combination with the weather may have damaged or may threaten to damage dikes. In this case, dikes can be sandbagged. Sandbags prevent water from flowing through, by the same principle as the actual dike that is re-enforced.
The World Meteorological Organization (WMO) and the Global Water Partnership together have organized the Associated Programme on Flood Management. The overall goal of Integrated Flood Management (IFM) is maximizing net benefits from flood protection measures (see above), while minimizing the loss of life from flooding.