Sediment Transport and Weathering Rate in the Marrecas River Basin in Southwestern Paraná

Abstract

The Marrecas River Catchment Basin, located in the Third Plateau of Paraná, is part of the Iguassu River Basin, with the Marrecas River as a tributary of the Santana River. The climate is superhumid mesothermal, and the relief is predominantly undulating (45.1%) and strongly undulating (29.6%). The soils are mostly Red Nitosol (52.5%), Litholic Neosol (24.9%) and Red Latosol (19.7%). Originally covered by Montane Mixed Ombrophilous Forest, the basin’s land use is currently focused on soybean crops, pastures, and reforestation, which occupy, respectively, 68.6% and 30.9% of the area. In 2023, the annual precipitation was 2,614.6 mm, with a peak of 574 mm in October. The fluviometric levels ranged from 2.11 m to 9.52 m, with an annual average of 2.7 m, while the average daily flow was 18.19 m³/s, reaching a maximum of 274.07 m³/s. The total volume of water discharged reached 573,520,608 m³, carrying 9,199.27 tons of SiO₂. Weathering, with a SiO₂/Al₂O₃ ratio of 5.52, indicates bissialitization with montmorillonite formation. The deepening of the weathering profile was 0.06615 mm, of which 0.0368 mm corresponded to mechanical erosion, resulting in an effective deepening of 0.02935 mm, evidencing soil formation superior to erosion and the environmental resilience of the basin.