Erosividade da chuva na Bacia Experimental de Aiuaba, semiárido cearense

Abstract

The study of rainfall erosivity is of great relevance due to its impacts on soil and the environment, especially in vulnerable regions such as the semiarid. However, there is a significant scarcity of erosivity data for areas like the Caatinga. This work aims to systematize disdrometer data, estimate kinetic energy, rainfall erosivity, and the raindrop drag coefficient in the Caatinga of the semiarid region of Ceará, particularly in the Aiuaba Experimental Basin. Erosivity was estimated based on the rainfall kinetic energy and the maximum intensity in 30-minute intervals, and compared with the erosivity factor equation of Wischmeier and Smith (1978). The development of a computational program enabled detailed analysis of disdrometer data and the calculation of erosivity for each rainfall event. The raindrop drag coefficient, a parameter required for calculating terminal velocity, remains unexplored in the Caatinga region. The results indicated that the measured kinetic energy was 1.9 times higher than that estimated by models and that the average rainfall erosivity was approximately twice as high as that obtained through the conventional method, highlighting the underestimation of erosive potential by the traditional model. The calibrated parameters for the monthly erosivity equation of the Caatinga resulted in higher values than those found for the temperate region of Brazil, confirming the need for regional adjustments. The findings of this research provide specific parameters for the Caatinga and may support improvements in models and the development of soil conservation strategies in semiarid areas.