Aspectos fisiográficos, caracterização dos solos e capacidade de uso das terras da bacia hidrográfica Lajeado da Onça, Ponta Grossa – Paraná

Abstract

This study aimed to perform a physiographic characterization and evaluate the land capability of the Lajeado da Onça watershed, located in the municipality of Ponta Grossa, in the Campos Gerais region of Paraná State, Brazil. The watershed covers approximately 67.83 hectares and is predominantly used for grain production. For the morphometric and physiographic characterization, Digital Elevation Models (DEMs) obtained through unmanned aerial vehicles were used, with data processed in open-source geoprocessing software, particularly QGIS 3.28.8 and its extensions QuickMap Services and SmartMap. The parameters analyzed included form index (Kf = 1.068), circularity index (Kc = 0.71), stream order (2nd order), drainage density (4.42), and slope. The Kf and Kc values indicate a shape close to circular, contributing to a moderate to high flood risk, and the high drainage density indicates rapid surface runoff. Slope analysis identified five classes: flat, gently undulating, undulating, strongly undulating, and mountainous. The steepest slopes are concentrated near the main watercourse, which is embedded in a geological fault. Current land use showed that 64% of the area is allocated to grain production, 23% to permanent preservation areas (PPAs), 9% to pine and eucalyptus plantations, and the remainder to roads, buildings (4%), and watercourses (0.15%). Land capability was assessed using the Land Capability Classification System, with slope and erosion processes (sheet and rill erosion) as the main limiting factors. Of the eight classes in the system, only classes I and V were not observed, indicating the heterogeneity of the watershed. Classes II and III were predominant, covering 69% of the area. Results showed that approximately 47.5% of the area is overused and requires changes in use or the adoption of conservation practices to prevent soil degradation. In classes VII and VIII, 100% of the area needs adjustments, while class VI requires changes in 83.35% of the area. Classes III and IV require conservation measures in 69.24% and 30.09% of their areas, respectively. The findings provide valuable information for environmental planning and sustainable watershed management and are essential for supporting soil and water conservation practices and future hydrological modeling in the region.