Derivation and validation of estimation model of rainfall kinetic energy under the canopy

Abstract. The interception effect of the canopy on rainfall alters the kinetic energy of the rainfall as it reaches the ground, which is crucial for soil and water conservation, ecosystem stability, and energy transfer within environmental systems. A novel estimation model for the kinetic energy of rainfall under canopy is developed by stratifying the canopy using parameters such as leaf area index and leaf inclination angle, explicitly distinguishing between canopy-dripped and splashed raindrops. The efficacy of the model is subsequently assessed and analyzed through a comprehensive examination of 9 field datasets encompassing LiDAR and raindrop spectrum observations. The simulated under-canopy total kinetic energy, splashing drop kinetic energy, and dripping drop kinetic energy showed average R² values of 0.788, 0.613, and 0.768, and average RMSE values of 19.9, 2.2, and 21.1 J/m²h, respectively. Simulations reveal that the canopy exerts a complex influence on the kinetic energy of rainfall beneath it, which may either increase or decrease depending on the physical characteristics of the canopy. The canopy may stabilize the raindrop spectrum and kinetic energy beneath it. Regardless of external variations, these parameters remain constant under an unchanged canopy.