Draaikolken
Draaikolken are vortices in which water moves in circles around a central axis. In Dutch usage the term covers both surface whirlpools and subsurface vortices that form in natural waterways and in man-made settings such as harbors, channels, and dams. They are characterized by a rotating flow pattern that can vary in size and duration.
Formation: Draaikolken arise when currents with different directions or speeds interact with topography. Changes in depth,
Characteristics: Depending on scale, a draaikolk may be visible at the surface as a spiraling water thread
Distribution and impact: Draaikolken occur in rivers, estuaries, and coastal waters worldwide, especially near bends, shoals,
Study and terminology: Scientists study draaikolken with in situ sensors, acoustic Doppler current profilers, and satellite