Evaluation of kinetic energy and erosivity potential of simulated rainfall using Laser Precipitation Monitor

- We used simulated rainfall and optical disdrometer.
- Strong relationship between intensity and kinetic energy is obtained.
- We found fairly good relationship between rainfall erosivity and depth.
- Kinetic energy is strongly matched with rain drop size than drop volume.

Rainfall kinetic energy is a widely recognized indicator of a raindrop's ability to detach soil particles in rainsplash erosion. However, it is challenging to estimate the kinetic energy (KE) of a given rain event, because it involves analysis of the terminal velocity and drop size distribution (DSD) of raindrops. A preferred alternative is to relate KE to rainfall intensity. Therefore we sought to characterize simulated rainfall, establish a relationship between kinetic energy and intensity as a function of both time (KEt, J m− 2 h− 1) and volume (KEvol, J m− 2 mm− 1), and examine the erosivity potential of each event. A rainfall simulator and Laser Precipitation Monitor (optical disdrometer) were used to characterize raindrop size, terminal velocity and KE at different rainfall intensities (1.5 to 202 mm h− 1). Values of KEt ranged from 26.67 to 5955 J m− 2 h− 1 and KEvol ranged from 16.10 to 34.85 J m− 2 mm− 1, which is comparable to values determined from natural rain of similar intensity ranges. A power-law function and a polynomial function between KEt and rainfall intensity had coefficients of determination (R2) of 0.99 and 0.98 (P < 0.0001), respectively. The best-fitting relationship between KEvol and intensity was a power-law function (R2 = 0.95; P < 0.001). We found that erosivity had a very strong correlation with rainfall depth (R2 = 0.99; P < 0.0001) in power-law function. Furthermore, regardless of rainfall intensity, KE is more strongly correlated with raindrop size than volume of raindrop.