Flow dynamics and shape of rinnenkarren systems

• We investigated the hollowings of the main channels of rinnenkarren systems.
• The hollowings develop at the conjunction sites of the channels.
• Turbulent zones develop at connecting rivulets thus, the solution capacity increases.
• The size of hollowings depends on the slope angle.
• The density of hollowings depends on the density of tributary channels.

The width and depth of the main channels were measured along the length of seven rinnenkarren systems on the floor of the glacier valley under the Tragl peak in the Totes Gebirge, Austria. The cross-section areas of the channels were calculated which were considered in relation to the distances between their location along the flow path and the margin of the slope. It can be stated that hollowings (local maxima) occur on the main channels at the connecting sites of the tributary channels. According to laboratory experiments, turbulent zones develop on the rivulet of the main channel, where the rivulet of the tributary channel joins the rivulet of the main channel. The length and the location of the turbulent zones depend on the slope angle, the joining angle of the tributary channel, the ratio of the water flow of the rivulets of the main and tributary channels as well as the water flow of the tributary channel. The pattern of the local maxima of the main channels is explained by the turbulence pattern which develops in the rivulets of the main channels. The turbulence pattern may be continuous (the turbulence is uninterrupted) or non-continuous (the turbulence is separated into turbulent zones of different lengths and densities). The length and density of turbulent zones determine the size and density of hollowings.