Assessment of anthropogenic pressure around peri-urban wetlands in the state of São Paulo, Brazil

Wetlands, essential for biodiversity conservation and ecosystem services, are increasingly threatened by land-use and land-cover change. This study analyses wetlands and their watersheds in São Paulo state, Brazil, where anthropogenic pressures reached wetland areas. Using data from 1985 to 2020, we assessed the expansion of impervious surfaces, its influence on runoff dynamics and projected a business-<i>as</i>-usual scenario for 2035. We also developed an index of the wetland's condition based on spectral trends and image classification. Results show that agricultural and urban expansions have intensified pressures on watersheds and that approximately 45% of wetlands are classified with low scores of condition, indicating ecosystem degradation. The 2035 scenario projects continued loss of natural areas, increased impervious surfaces, and higher watershed runoff. This study underscores the urgent need to incorporate wetland conservation into land-use planning, particularly in agricultural and urban contexts, to safeguard these critical ecosystems and avoid further losses.