Estimativa da erodibilidade dos solos da microbacia hidrográfica de Vaca Brava, Areia-PB, utilizando diferentes modelos.

Abstract

The use of mathematical models and geostatistics to evaluate soil erosion is a strategy of fundamental importance for agricultural and environmental planning, especially in areas of family farming inserted in the domains of watersheds. Thus, the aim was to estimate the soil erodibility of the Vaca Brava watershed, in the mesoregion of Agreste da Paraíba, using different models. The Vaca Brava watershed has an area of 14,03 km2 , including the municipalities of Areia (06°5748" S and 35°41'30" W; 618 m a.n.m.) and Remígio (06°53'30" S and 35°49'51" W; 535 m a.n.m). Information on the average monthly precipitation for the municipality of Areia (PB), in the period between 1994 and 2019 was used to obtain the rainfall erosivity (R-factor). Data of soil total sand, silt, clay, organic carbon and organic matter contents (n = 360) were inserted in three models to estimate the soil erodibility (K factor), using the EPIC, Torri and Shirazi models. The results were evaluated by descriptive statistical analysis and spatial distribution maps of the textural fractions obtained by means of the kriging interpolation technique. The estimated annual erosivity was 4313 MJ ha-1 mm year-1, classified as medium erosivity. The greatest spatial variability was verified for total sand and silt contents, while clay contents presented the least spatial variability. Regarding the estimate K factor, the mean values of 0.0187, 0.0287 and 0.0225 t hm2 h/(MJ mm hm2 ) were verified for the obtained EPIC, Torri and Shirazi values, respectively, being the EPIC model the one that best fitted the data, followed by the Torri model. We conclude that the erosivity depends on the volume of rainfall and increases in the months of higher precipitation, June and July, with EI30 values of 9953 and 9579 MJ ha-1 mm h-1, respectively. The study of the spatialization of the textural fractions indicated a high concentration and distribution of total sand and silt contents, indicating the need to adopt soil management practices that contribute to the conservation of soil and water.