Dykes

A dyke (also spelled dike) is a long, raised embankment built to prevent flooding from seas, rivers, or lakes. Dykes are a key element of flood protection in low-lying regions and are designed to keep land dry during high-water events. They are distinct from dams, which block water, and from sea walls that primarily reflect wave energy.

Construction and design: Most dikes are earthworks with a stable core, often clay, faced with stone or concrete to resist erosion. A typical cross-section includes a crest for access and maintenance, a core to resist seepage, and upstream drainage or seepage control features. Heights and crest widths vary with risk; modern practice uses geotechnical analysis, water level monitoring, and pump systems for inland drainage.

Types and examples: Coastal sea dikes hold back the sea; river dikes protect settlements from river floods; polder dikes enclose drained land that is kept dry by pumping. In the Netherlands, extensive dike systems are part of the Delta Works; in other regions, dikes protect cities, farms, and ports.

Maintenance and risks: Dikes require constant upkeep; erosion, subsidence, seepage, and overtopping can lead to breaching. Climate change and sea-level rise increase the need for heightening and reinforcing dikes, as well as new barriers.