Quantifying the time-specific kinetic energy of simulated rainfall using a dynamic rain gauge system

Abstract

Raindrop impact derives from the kinetic energy of falling raindrops. Determining the kinetic energy of rainfall requires the size distribution and terminal velocity of raindrops, which necessitates complex instrumentation. To avoid this, empirical relations have been developed that relate rainfall intensity and the rate of kinetic energy, i.e., time-specific kinetic energy (KE_time). In this study, a dynamic rain gauge system (DRGS) was used to quantify the KE_time generated by a rainfall simulator without need of measuring raindrop size distributions or impact velocities. In a series of 10 rainfall tests, the KE_time and rainfall intensity were 860.9 (±88.6) J m² h⁻¹ and 72.1 (±1.9) mm h⁻¹, respectively. Estimated KE_time was found to agree well with the power-law relation presented by Petrů and Kalibová for high-intensity simulated rainfall, which are the conditions when higher deviations occur. The DRGS may be a useful tool in quantifying the KE_time of rainfall simulators in hopes to better understand raindrop impact mechanisms.