Advancing Water Resource Management in Brazil through Integrated Hydrology Modeling of the São Paulo Guarani Aquifer Outcrop Zone

• Grant number: 26/00959-6
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: July 01, 2026
• End date: June 30, 2027
• Field of knowledge: Physical Sciences and Mathematics - Geosciences
• Principal Investigator: Edson Cezar Wendland
• Grantee: José Gescilam Sousa Mota Uchôa
• Supervisor: Reed M Maxwell
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Institution abroad: Princeton University, United States
• Associated to the scholarship: 23/13160-8 - IMPACT LAND USE AND LAND COVER AND CLIMATE CHANGE ON HYDROLOGICAL FLOWS BETWEEN GROUNDWATER AND SURFACE WATER IN THE GUARANI AQUIFER OUTCROP ZONE, BP.DR

Abstract

Groundwater-surface water interactions are fundamental to sustaining ecosystems, regulating water availability, and supporting water security. The hyporheic zone, where these systems mix, performs essential ecological functions, yet remains poorly understood in tropical regions, particularly under pressures from land-use change and climate variability. The Guarani Aquifer System (GAS), a major freshwater resource for São Paulo State, is especially vulnerable in its outcrop areas, where groundwater-surface water exchanges occur, and anthropogenic impacts are concentrated. This project seeks to advance the characterization of hydrological processes in a representative GAS recharge area, the Onça Creek Basin (OCB), which benefits from more than two decades of monitoring data. A distributed integrated hydrologic model (ParFlow) will be implemented, calibrated, and validated for the OCB to assess how historical and future climate and land-use changes influence recharge, baseflow, and flow seasonality. Future scenarios (2050 and 2100) will be explored to identify thresholds of hydrological and ecological vulnerability, particularly in relation to drought intensification and shifts toward crops with higher evapotranspiration demand. Hydrological indicators such as the baseflow index and effective area will be applied across multiple São Paulo GAS basins to extend insights beyond the OCB. By integrating indicators and numerical modeling, this project will provide scientifically robust and practically useful knowledge to support sustainable groundwater management, inform policy decisions, and improve ecosystem resilience in the São Paulo GAS outcrop zone under ongoing environmental change. (AU)