|Rieke-Zapp, D - PURDUE UNIVERSITY|
|Poesen, J - LEUVEN, BELGIUM|
Submitted to: International Soil Conservation Organization Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 23, 1999
Publication Date: N/A
Technical Abstract: In recent times people become more and more interested in the role rock fragments play in soil erosion. Therefore, flume experiments were conducted in which overland flow was applied to a typical Miami Silt Loam (fine-silty, mixed, mesic Typic Hapludalf) a typical soil of the Midwest of the United States. The study focused on four different treatments: slope (7 and 14%), discharge (5,7 and 11,4 L/min), rock fragment content (0; 5; 10; 20, 40 Vol.%) and time. The results show the development of an erosion pavement over time and a kind of armoring for soils containing rock fragments. The Intensity and the speed of developing this pavement depend on slope, discharge and initial rock fragment content. An increase of the rock fragment cover ontop of the erdoing surface leads to an armoring effect reducing soil loss that can be plotted in different ways for illustration. The more rock fragments are applied to the soil the less sediment yield was observed in general. It was part of the experiments to use a laser scanner and other methods to evaluate soil surface roughness and the increase of stone cover during the experiments to find a method of measuring the covering or armoring effect. Reynolds number, Froude number and Darcy-Weisbach coefficient were calculated and plotted versus time to find a relationship for the decrease of soil loss due to a rising covering effect. It was found that rills form narrower and deeper in soil material with less stones applied. For turbulent flow Darcy-Weisbach coefficient is positive correlated to Reynolds number due to the development of headcuts one can not refer from hydraulic flow data to an increase in surface armoring.