Measurement and modelling of kinetic energy and erosivity of rainfall and throughfall in a tropical semiarid region.

[Display omitted] • Rainfall (R) and throughfall (TF) were measured over 18 months in a dry forest. • Canopy reduces kinetic energy (KE) and rainfall erosivity (EI30) by 30% and 39%. • Higher attenuation of KE and EI30 was observed in the season with high leaf density. • Wischmeier and Smith (WS) model underestimates kinetic energy in the study region. • WS model was recalibrated and validated for R and TF in the tropical semiarid site. Empirical relationships have been widely used to estimate kinetic energy of rainfall (KE) and its erosivity potential (EI30) due to scarcity of direct and continuous measurements. Two disdrometers were installed − one in an open field and another under the canopy − in a fragment of Tropical Dry Forest (TDF) in a semiarid region, Northeast of Brazil, to quantify the role of the canopy on attenuating rain kinetic energy and erosivity potential, for all events and at the seasonal scale. The data was also used to test available KE and EI30 models, as well as to recalibrate the models for the study area. Data were collected from December/2019 to July/2021, totaling 95 events. Rainfall (R) was higher than throughfall (TF) due to canopy interception, but rainfall duration and the total number of drops were higher under the canopy. The TDF canopy reduces rainfall kinetic energy by 30% and its erosivity potential by 39%, with higher KE and EI30 attenuation being observed during the high leaf density stage, which highlights the major seasonal role of this vegetation in protecting the soil surface from the impact of raindrops and, consequently, against erosion. The relationship between KE and mean intensity of R and TF is best expressed as a function of time (J m−2 h−1), by a linear model (r2 > 0.98 – p-value = 0.000). The Wischmeier and Smith-WS model for KE and EI30 was recalibrated for the semiarid region, underestimating KE of open field rainfall by 2% and overestimated TF KE by 1%, against underestimations of 24% and 20% of the original model for R and TF, respectively. The results presented here contribute to understanding the role of dry forests in attenuating the erosivity potential of the rainfall in semiarid environments, as well as to improving the capacity on predicting rainfall and throughfall erosivity under such conditions. [ABSTRACT FROM AUTHOR]