Evolution of soil loss and evaluation of different terrace spacings in the Inhacanga River micro-watershed, using the AGNPS model

The northwestern region of the state of Paraná has undergone deep transformations in its land use, occupation, and management, resulting in environmental degradation and water contamination. The objective of this work was to evaluate soil conservation practices in the Inhacanga River micro-watershed in Altônia, Paraná state, using the AGNPS model and geoprocessing techniques in ArcGIS software. Thus, scenarios were developed to analyze the existing agricultural systems and to compare different terrace spacings, considering the 2019/2020 summer and exposed soil conditions. Sediment production was estimated based on rainfall records from the historical hydrosedimentological monitoring series. In the 2019/2020 summer scenario, with the adoption of terraces, a reduction in potential erosion areas of 13.21% was observed; in sediment production, of 15.38%; in solid runoff, of 35.93%; and in flow, of 31.66%. In the exposed soil condition, potential areas reduced by 5.51%; sediment production, by 9.36%; solid discharge, by 56.63%; and flow, by 15.85%. It should also be noted that the best results were obtained with variations in terrace spacing greater than 49%, 50%, and 53%, compared to the other recommended values.