cascády

Cascády are a natural or artificial sequence of water features in which water descends over a series of steps, creating multiple small waterfalls. In the natural landscape, cascády form where riverbeds intersect with rock layers of varying hardness or where joints and faults create a stepped topography. Differential erosion and geological uplift over time contribute to their arrangement. They are common in alpine and karst regions, and can be part of larger waterfall complexes or creek systems.

The hydraulic character of cascády involves changes in velocity, turbulence, and aeration as water drops from one tier to the next. The stepping also influences sediment transport and aquatic habitats, providing diverse microhabitats; pool-and-riffle patterns can develop between stages.

Cascády are also used in human design. In landscaping, artificial cascády are built to provide visual interest, sound, and microclimate effects; they typically consist of a sequence of basins, rocks, and a retaining structure that controls flow. In civil engineering, cascade structures are used to dissipate energy in spillways and to convey water gradually in hydroelectric installations.

The term can also describe a cascade of effects in systems or processes, such as cascading failures in power grids or cascading style sheets in web design, though those uses are abstract extensions of the water-related concept.