Aplicação da equação universal de perdas de solos revisada (RUSLE) na quantificação da erosão laminar na bacia hidrográfica do Rio Verde – Região Oeste do Paraná

Abstract

Water erosion is the disintegration of soil particles due to the action of water that occurs mainly through precipitation and is considered the most common form of erosion in tropical regions such as Brazil. This study aimed to estimate the average annual soil loss in the Rio Verde River Basin using the Revised Universal Soil Loss Equation (RUSLE) by using the QGIS 3.16.10 software. The study area is in the western region of Paraná state and drains eight municipalities, the Verde River is a left-bank tributary of the Piquiri River. The erosivity (R) found for the study area ranged between 11,629 (maximum) and 10,612 MJ mm ha-1 h-1 month-1 (minimum) and it tends to decrease in the south-north direction. The soil erodibility (K), linked to the intrinsic characteristics of the soil, was defined from the literature review, and varied according to each type of soil, with 0.03 being the maximum value and 0.0204 t ha h MJ-1 ha-1 mm-1 the minimum. The slope length and slope factor, which defines the topographic factor (LS), indicates that 63.89% of the basin area, had an estimated topographic factor between 0 and 1 (dimensionless). The predominant relief in the study area is classified as gently sloping, that is, with a slope between 3 and 8%. The factor of land use and management and conservation practices (CP) was estimated from the land use map and literature review. The use of land for agriculture is predominant, being the main use in 78.07% of the basin. Agriculture and exposed soil scored the highest CP factor: 0.04105 and 1, respectively. The estimated mean annual soil loss was maximum 38.15 t ha-1 year-1 and had an average of 9.31 t ha-1 year-1, which is classified as none or slight. The Soil Loss Tolerance shows that 16.68% of the basin is considered a critical area, that is, where the annual soil loss is higher than the tolerable one. Soil is an important natural resource from an environmental, social, and economic point of view, especially in regions that have agricultural activities as the basis of their economy. The maps and results obtained serve as a tool for better management of natural resources, such as soil and water, by identifying critical and priority areas for the adoption of soil conservation practices.