What is a stone dike?
A stone dike, in Dutch stenendijk, is a dike whose slope is weighted or faced with stone so that it can withstand waves, currents and ice. In engineering terms the stone layer is a revetment. It protects the clay or sand core from being washed out, where waves would strip the grass and clay from an unprotected slope.
Older Dutch dikes were often faced with brick. Today concrete blocks, concrete columns and natural stone are mostly used. Set basalt columns are the classic Dutch revetment: an estimated 5 million m² of basalt column work lines Dutch dikes and waterways. Beneath the top layer is a filter layer that stops the subsoil from washing out through the joints, and the toe is often protected by a berm of rock armour.
A well-known example is the Stenendijk in Hasselt (Overijssel) along the Zwarte Water, a Dutch national monument listed as a “historic stone sea defence”. It is being strengthened with a steel sheet pile wall in the crest, so the historic stone facing can stay.
Recognising it
The slope is fully or partly covered with set stones or columns instead of just grass, usually from the toe up to the zone that waves can reach.
Application
- Never work on a dike without permission. In the Netherlands, digging, building or planting in a dike protection zone needs a permit from the water board; in other countries the flood defence authority has similar rules.
- Report damage straight away. Sunken or loose stones, holes and washed-out joints are weak points. Report them rather than repairing them yourself.
- Never remove stones. Even one missing stone can be where scouring starts in a storm.
- Historic dikes. On listed dikes, strengthening is often done by inserting a sheet pile wall rather than replacing the facing.
Common mistake: assuming stone makes a dike indestructible. Without an intact filter layer, the material under the stones washes away and the revetment collapses.
Related terms
- Dike monitoring
- Basalt
- Rubble stone
- Concrete block
- Emergency dike
- Pile dike
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