Integrated hydro-environmental assessment of the Parnaíba River Basin: Interactions among streamflow, groundwater, and land use

The Parnaíba River Basin (PRB), located in Northeastern Brazil, is a strategic water system that supports urban supply, agriculture, and energy production. This study provides an integrated hydro-environmental assessment, emphasizing streamflow dynamics and groundwater contributions. The flow regime is highly seasonal, with groundwater sustaining much of the discharge during the dry season. Baseflow Index (BFI) values ranging from 0.75 to 0.80 indicate a substantial contribution of baseflow to total streamflow. Trend analyses revealed consistent declines in total streamflow, baseflow, and quickflow across all monitored stations, with an average reduction of 4.7% per decade—totaling approximately 19.7% between 1982 and 2023 at the Alto Parnaíba station. Although no significant trend was observed in precipitation, rising temperatures, reduced actual evapotranspiration in key areas, and extensive groundwater extraction point to growing pressure on the basin’s water resources. Land-use changes—including agricultural expansion and forest loss, particularly in the MATOPIBA region — combined with advancing aridity, further contribute to hydrological imbalance. These findings highlight critical risks to water availability, aquatic ecosystems, and the sustainability of multiple water uses. Addressing these challenges requires a structural shift in water management, aligned with the UN Sustainable Development Goals and grounded in both scientific evidence and local knowledge. Key actions include integrated water resources management, rational use of groundwater, continuous monitoring of hydroclimatic conditions, conservation of natural ecosystems, and sustainable land-use planning.