Assessing Rainfall Kinetic Energy – Rain Intensity Relationship through Field Observations

This study evaluates efficacy of rainfall kinetic energy (KE) and rain intensity (I) relationship through field observations under different wind conditions.  KE-I relationship is critical for various applications.  For example, rain-induced soil erosion, for which KE is an important indicator of potential rain splash erosion, may cause severe environmental and agricultural issues during, especially, heavy rainfall events.  Fertilizers removed from the soil due to rain-induced erosion pollute waterbodies, silt up the basin, and reduce basin capacity that may trigger flooding.  In this study, the KE-I relationship was investigated using raindrop size and fall speed measurements by a disdrometer and wind speed measurements by a 3D Ultrasonic anemometer.  Rainfall events considered in this study were selected from a 3-year long field campaign conducted at our outdoor rainfall laboratory located on the West campus of the University of Texas at San Antonio, Texas, USA.  Using these measurements, different KE-I relationships reported in the literature were evaluated through statistical analyses.  A new parameterization for the KE-I relationship was also developed based upon our field observations, and wind-induced effects on KE-I relationship are discussed.  The results of this investigation with potential implications will be discussed in this presentation.  This material is based upon work supported by the National Science Foundation under Grants No. AGS-1741250.