Water quality management and socio-hydrology strategies for an urban basin

Human-water systems evolve at different rates, requiring socio-hydrological approaches for effective water management. In Brazil, the Water Body Classification (WBC) guides Water Quality (WQ) management, although participatory processes remain limited. This study analyses the urbanized Upper Iguassu River Basin by integrating socio-economic and hydrological data over a 12-year period within a socio-hydrological framework. A timeline was developed to represent governance, hydrological, and socio-economic dynamics in water resources planning. No clear correlations were identified between socio-economic characteristics and WQ, indicating relatively uniform impacts across the basin. Domestic wastewater was identified as the main pollution source. The basin’s economy grew by 179%, driven mainly by the service sector, while sewage treatment did not expand proportionally, intensifying pollution. The same population contributing to economic growth also participates in governance processes, revealing a mismatch between development and sanitation investments. Decentralized participatory governance evolves gradually, requiring long-term monitoring to support sustainable water management.