A water dike is an engineered structure designed to control, divert, or block the flow of water. These continuous barriers manage water bodies and protect low-lying land from inundation. Dikes are a component of water management, providing defense for human populations, infrastructure, and agricultural areas against forces like tides or high river stages. They are recognized globally for their importance in flood protection and land development.
Defining the Structure
A dike is an embankment, typically an artificial wall of compacted earth, built parallel to a body of water like a coastline, river, or lake. The core purpose of this linear structure is to provide continuous protection from flooding, acting as a permanent boundary between water and the protected land. Dikes are instrumental in land reclamation, enabling the development of areas that would otherwise remain submerged.
The physical design of a dike usually features a trapezoidal cross-section with sloping sides that enhance stability and dissipate the energy of waves or currents. This shape provides the necessary volume and weight to resist the lateral pressure exerted by the retained water. Construction materials consist of compacted soil, sand, and clay, which are layered and pressed to form a stable mound.
To prevent water from seeping through the foundation (piping), a highly compacted, impermeable clay core is often incorporated. This core acts as a cutoff wall, ensuring the structure remains watertight. The outer slopes are frequently armored with materials like rock layers, known as riprap, or concrete to resist erosion caused by wave action or fast-moving currents.
Distinguishing Dikes from Related Structures
Dikes, levees, and dams are all hydraulic structures, but they differ in function, location, and scale. The term “dike” traditionally refers to a barrier that protects land which would otherwise be underwater, or a complete enclosure system for land reclamation. Dikes maintain a permanent boundary against a water source, such as the sea.
Dike vs. Levee
While the terms are frequently interchanged, a distinction is often made based on location and the permanence of the threat. Dikes are generally associated with coastal protection or the enclosure of low-lying lands to create polders, holding back water almost constantly. Levees, conversely, are linear embankments built alongside rivers to protect adjacent dry land from seasonal high water or periodic flood events. They are designed to contain a river during temporary rises in water level, rather than holding back a permanent sea or lake.
Dike vs. Dam
The difference between a dike and a dam centers on their orientation relative to the water flow. A dike is built parallel to a waterway or coastline to keep water out of a specific area. A dam, by contrast, is built across a waterway, such as a river, to impound water and create a reservoir. Dams are primarily designed for water storage, flow regulation, or power generation, while dikes are purely for lateral protection and containment.
Types and Construction Methods
Dikes are classified based on their protective function and location, with designs tailored to the forces they must withstand. Sea Dikes are robust coastal structures built to defend against storm surges and tidal influences, often requiring extensive armoring to resist powerful wave energy. River Dikes run alongside rivers to contain high-flow events and prevent overflow onto floodplains.
A specialized type is the Ring Dike, which forms a continuous, closed embankment built around a vulnerable area, such as a polder in the Netherlands. This design allows for the drainage of the enclosed land, effectively reclaiming it for use. Construction begins with site preparation to ensure a stable foundation, which is necessary for the structure’s long-term integrity.
A common construction technique involves excavating a key trench along the dike’s centerline, especially on soft ground. This trench is filled with highly compacted, impervious material like clay to create a waterproof barrier deep beneath the embankment, preventing subterranean seepage. The body of the dike is then built up in layers, with the final outer slope protected by armor like riprap (a layer of loose stone) or specialized geosynthetics to secure the soil against erosion.