HYDROLOGICAL MODELING IN URBANIZED BASINS: THE IMPACT OF LAND USE CHANGE USING THE CN METHOD

Abstract

Changes in land use and land cover, especially in urbanized areas, have significantly impacted the hydrological regime of river basins, intensifying surface runoff and peak flows. In this context, this study sought to investigate the impacts of these changes in the sub-basins of the Fojo and Perdizes streams, in Campos do Jordão, SP, answering the question: how do changes in land use and land cover impact the hydrological regime of the sub-basins, and how can the CN (Curve Number) method be applied to estimate these impacts? The objective was to stimulate water resilience through the application of the CN method, associated with the use of geoprocessing tools, to estimate design flows in different scenarios. The results revealed that, between 2002 and 2022, forest areas decreased by 6% in the Perdizes sub-basin and 18% in the Fojo sub-basin, with a corresponding increase in urbanized areas and land use mosaics. This transformation increased peak flows, especially at high return times (50 and 100 years), with maximum values ​​of 18 m³/s in the Fojo stream and 7 m³/s in the Perdizes stream in 2022. In addition, a reduction in the concentration time was observed, indicating faster and more intense runoff, especially in the Fojo sub-basin due to the greater slope and contribution area. The results demonstrate the hydrological impacts of anthropogenic pressures and highlight the need for sustainable management strategies, reinforcing the importance of public policies to mitigate the effects of changes in land use and promote water resilience in the region.