Natural Infrastructure in São Paulo’s Water System

The report assesses the potential for natural infrastructure to complement the Cantareira Water Supply System in São Paulo, Brazil. Using a Green-Gray Assessment, it finds that targeted reforestation of 4,000 hectares could reduce sediment pollution by 36%, yielding a 28% return on investment over 30 years by reducing water treatment and dredging costs. While forest restoration is likely to slightly increase dry season water flows through a 'sponge effect' and fog capture in cloud forests, the overall impact on annual water availability is estimated to be marginal. The document provides a roadmap for scaling these investments, suggesting blended finance models and improved landowner engagement to overcome risks and uncertainties.

• Targeted restoration of 4,000 hectares of native forest in priority areas of the Cantareira watershed could reduce sediment pollution by 36%, compared to only 8% if the same area were reforested at random.
• The investment for the R4000 reforestation scenario is estimated at approximately US$37 million, which would generate avoided costs of $106 million and a net benefit of $69 million over 30 years, representing a 28% return on investment (ROI).
• The primary financial benefits of the R4000 scenario come from reduced water management costs, specifically water treatment (saving $92.4 million), dredging (saving $11.9 million), and equipment depreciation (saving $1.4 million).
• Forest restoration is modeled to have a marginal impact on total annual water availability (+/- 0.2%), but it is likely to increase dry season baseflows through the 'sponge effect' and fog capture in high-altitude cloud forests.
• Conserving 1,900 hectares of existing forest to prevent projected deforestation would result in a 14% ROI and a positive net present value of $390,000, though this is lower than the returns for restoration.
• The financial viability of the R4000 project is most sensitive to the level of sediment retention and the discount rate; however, it remains viable even if restoration costs increase by 35%.
• Scaling natural infrastructure in the region requires addressing barriers such as the need for detailed watershed plans, better landowner engagement, and the development of blended finance models to attract risk-averse investors like Sabesp.

APA

OZMENT, S., FELTRAN-BARBIERI, R., HAMEL, P., GRAY, E., RIBEIRO, J. B., BARRÊTO, S. R., PADOVEZI, A., & VALENTE, T. P. (2018). Natural Infrastructure in São Paulo’s Water System. World Resources Institute. https://wriorg.s3.amazonaws.com/s3fs-public/18_REP_SaoPauloGGA_finalweb.pdf

Chicago

OZMENT, SUZANNE, RAFAEL FELTRAN-BARBIERI, PERRINE HAMEL, ERIN GRAY, JULIANA BALADELLI RIBEIRO, SAMUEL ROIPHE BARRÊTO, AURÉLIO PADOVEZI, and THIAGO PIAZZETTA VALENTE. Natural Infrastructure in São Paulo’s Water System. World Resources Institute, 2018. https://wriorg.s3.amazonaws.com/s3fs-public/18_REP_SaoPauloGGA_finalweb.pdf.

Wikipedia

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BibTeX

@techreport{ozment2018natural, author = {OZMENT, SUZANNE and FELTRAN-BARBIERI, RAFAEL and HAMEL, PERRINE and GRAY, ERIN and RIBEIRO, JULIANA BALADELLI and BARRÊTO, SAMUEL ROIPHE and PADOVEZI, AURÉLIO and VALENTE, THIAGO PIAZZETTA}, title = {{Natural Infrastructure in São Paulo’s Water System}}, institution = {World Resources Institute}, year = {2018}, url = {https://wriorg.s3.amazonaws.com/s3fs-public/18_REP_SaoPauloGGA_finalweb.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }