Assessment of the changes in contributions from water sources to streamflow induced by urbanization in a small-sized catchment in Southeastern Brazil using the dual stable isotopes of water (O and H).

Urban growth often results in changes in the urban hydrological cycle, causing impacts on water availability in densely populated regions. The water isotopologues can provide relevant information about the origin of water under different hydrogeological scenarios, aiding to implement better strategies for water conservation in coupled natural-urbanized environments. In this study, the isotopic compositions of multiple water sources were assessed in a pristine (Ipanema National Forest, FLONA) and an urbanized (Lavapés catchment, SOR) watershed located in the Sorocaba River basin (State of São Paulo, Southeastern Brazil), seeking to understand the causes of isotopic variability and to determine the relative contribution from different sources to streamflow, using the Bayesian mixing model approach.

Intra-annual oxygen isotopes in the tree rings record precipitation extremes and water reservoir levels in the Metropolitan Area of São Paulo, Brazil.

The impacts of climate change on precipitation and the growing demand for water have increased the water risks worldwide. Water scarcity is one of the main challenges of the 21st century, and the assessment of water risks is only possible from spatially distributed records of historical climate and levels of water reservoirs. One potential method to assess water supply is the reconstruction of oxygen isotopes in rainfall.