The kinetic energy field under a rainfall simulator

Foltz, R.B.; Luce, C.H.; Stockton, P. 1995. The Kinetic Energy Field Under a Rainfall Simulator. Watershed Management Planning for the 21st Century, Committee on the Water Resources Engineering Division/ASCE, Aug 14-16,1995, San Antonio, TX.

Keywords: kinetic energy, rainfall simulator

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Abstract: Rainfall simulators are commonly used to estimate erodibility parameters for physically-based erosion models. Rainfall produced by the simulators should have kinetic energy delivery rates comparable to natural rainfall and the kinetic energy field under the simulator should be uniform. We used a calibrated piezoelectric crystal-based instrument to measure the raindrop splash power of a modified Purdue rainfall simulator. Measurements were taken at several points for three intensities (30, 50, and 100 mm/hr) and on a large grid at an intensity of 50 mm/hr. Raindrop power varied linearly from 0.116 W/m² at a rainfall intensity of 30 mm/hr to 0.391 W/m² at an intensity of 100 mm/hr, about half of that theoretically predicted for natural rainfall. On a closely spaced grid under 50mm/hr rainfall, power varied from 0.103 W/m² to 0.292 W/m², a ratio of 1:3. The difference between the measured power and the power of natural rainfall and the high variability in the kinetic energy field raises questions about the validity of erodibility values derived from the simulator. Further testing of the piezoelectric crystal instrument will help validate these results.

Moscow FSL publication no. 1995c