The Simulation of Rillenkarren

Abstract

<p>The development of Rillenkarren surfaces on plaster and salt has been simulated in a series of analogue experiments using a laboratory rainfall simulator.</p> <p>The experiments determined that rainfall is the dominant process controlling the development of Rillenkarren. The length of rills is related to the angle of slope of the exposed surface. The rill cross-section approaches that of a parabolic channel. The width of the rill appears to be determined by properties of the material: on plaster and salt characteristic width and depths were established. No experiments were carried out on limestone in the laboratory.</p> <p>The development of a Rillenkarren surface in nature is unique. The laboratory experiments have determined that such a surface represents one of rim effect adjusting to the process of rainfall (the random distribution of water droplets of a size range less than 0.2 mm to approximately 4.5 mm in diameter, falling at speeds close to their terminal velocities). The physics of such a phenomenon do not appear to have been investigated and it is suggested that very considerable dynamic analysis would be required to further the observations reported here.</p>