Dike

Dike is an artificially constructed wall to manage the water level or protect the land from the water rise under the extreme condition. The word “dike” mostly originated from Dutch “dijk”. The Dutch and its ancestors has been working to protect the land from the sea for over 2000 years, with the Frisians, the first tribe who settled in the Netherlands, are the ones who began to build dikes to prevent the land from water.

In the modern times, dike is mostly located along the river course or at the low-lying coastlines. They act as river and coastal flood prevention system. Dike also can be used to provide a reliable way for the ships. It can control the natural course of water, and makes it higher and faster. In the Netherlands, dike also becomes a part of larger system called polder. In which it becomes the wall that enclosed and protect the low-lying land from outside water.

There are four types of dikes in the Netherlands, which are river, coastal, estuarine dikes, and the embankments around boezem water, such as canal or lake which are also used as retention basins to regulate water level. They have different requirements in design and construction 1.

 

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Typical sea dike cross section (2)

 

There are also some principal elements need to be considered to achieve a reliable function, as follow 1:

1. The water level should not exceed the dike height, or the overflowing should be quite small, based on scientifically calculated criteria

2. Watertight cover should be layered on top of the outer slope, to keep the inner groundwater table and leakage low and give resistance towards earthquake or rapid draw down

3. The slope must be able to resist erosion, which can be done through a surface of healthy layer of turf for non-tidal river area, or stone or concrete blocks for high-tidal river or coast

4. Permeable cover should be layered on top of the inner slope, to keep the inner groundwater table and leakage low and make stable under earthquake

5. The core of the dike conveys the horizontal load due to the water and the subsoil (a layer of soil under the ground surface soil)

6. The subsoil provide suitable stability and water retaining function

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Application of dike system in the Netherlands ©fredhoogervorst

 

Footnote:

1. TU Delft. Dike Technology. Available from: http://geo.citg.tudelft.nl/~uffink/syllabusCT3320/part4/40/dike_technology.pdf
2. Linham, M. and Nicholls, R.J. Technologies for Climate Change Adaptation: Coastal erosion and flooding. TNA Guidebook Series. UNEP/GEF. 2010

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