Location: Agroecosystems Management ResearchTitle: Quantifying the time-specific kinetic energy of simulated rainfall using a dynamic rain gauge system
|Wacha, Kenneth - Ken|
|Huang, Chi Hua|
|PAPANICOLAOU, THANOS - Iowa State University|
|HATFIELD, JERRY - Retired ARS Employee|
Submitted to: Agricultural & Environmental Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2021
Publication Date: 3/25/2021
Citation: Wacha, K.M., Huang, C., O'Brien, P.L., Papanicolaou, T.N., Hatfield, J.L. 2021. Quantifying the time-specific kinetic energy of simulated rainfall using a dynamic rain gauge system. Agricultural & Environmental Letters. 6(1). Article e20042. https://doi.org/10.1002/ael2.20042.
Interpretive Summary: Soil erosion processes begin with raindrop impact. The amount of energy raindrops deliver to the soil varies with drop size and how fast they are falling. Because measuring these raindrop characteristics are complex, studies have developed relationships with rainfall intensity. However, many of these relations were developed in natural rainfall and don't do a good job at higher rainfall intensities. In this study we introduce an alternative method that doesn't require complex instrumentation. We use a Dynamic Rain Gauge System that has a collection of rain gauges mounted to a bar that spins at various speeds. A rainfall simulator is used to simulate repeatable high intensity rainfall testing conditions. At the end of a rainfall test, the mass of rainfall collected in the gauges and the speed the gauges were revolving is used to estimate raindrop energy. Results showed the amount of energy in simulated rainfall was 2.5 times less than estimates using well established rainfall intensity relationships. This system can provide a quick assessment of rainfall energy and better inform us on the mechanisms of raindrop impact and erosion processes.
Technical Abstract: Raindrop impact derives from the kinetic energy of falling raindrops. Determining the kinetic energy of rainfall requires the size distribution, terminal velocity and volume of raindrops, which necessitates complex instrumentation. To avoid this, empirical relations have been made between rainfall intensity and the time-specific kinetic energy (KEtime). In this study, a Dynamic Rain Gauge System (DRGS) is used to quantify the KEtime generated by a rainfall simulator without need of measuring raindrop size distributions or impact velocities. In a series of 10 rainfall tests, the KEtime and rainfall intensity were 860.9(±88.6) J m2 h-1 and 72.1(±1.9) mm h-1, respectively. Estimated KEtime found to agree well with the power-law relation presented by Petru and Kalibová for high intensity simulated rainfall. The DRGS may be a useful tool in quantifying the KEtime of rainfall simulators in hopes to better understand raindrop impact mechanisms.