Rainfall Intensity as a Measure of Storm Erosivity1
- P. C. Ekern2
The erosivity of storms should be proportional to the additive kinetic energy from the impact of falling rain and shallow flow of water. The erosivity of shallow water should be proportional to the proximity of the maximum velocity thread to the soil surface and the square of that maximum velocity. Relations among velocity, slope, and discharge suggest the following function for erosivity:
Erosivity = f [(discharge rate)1.0 (slope)1.0]
Evaluation of data suggested that the relation was reasonable, though a slightly higher value than the first power of the discharge was generally found.
When discharge in turn was related to rainfall intensity, the erosivity for shallow flow became:
Erosivity = f [(storm intensity)1.46 (slope)1.0]
The impact energy of rainfall was found to be a nearly identical function of intensity and slope so that the additive energy of shallow flow and drop impact should approximate the 1.5 power of the storm intensity.
Examination of the envelope for maximum soil loss from fallow plots of silt loam on 16% slopes at LaCrosse, Wis., showed such a relation to the 1.5 power of the rainfall intensity.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © .