The researchers responsible for the study are Stella Manes, PhD student in Ecology at Rio de Janeiro Federal University, and Aliny Pires, professor in the Ecology department of Rio de Janeiro State University. This study, entitled “Flood Prevention in Rio de Janeiro: Nature-Based Solutions as Adaptation to Extreme Weather Events”, has just received an award from the State’s Environmental Institution (INEA), which awarded studies on ‘Nature-based Solution for Sustainable Development’. The study will be published in the scientific journal of the institution in 2022. The main goal was to award academic research proposing solutions that could translated into action in the state. The researchers have been working with nature-based solutions and how these can revert climatic risks to nature’s contributions to people in their research group (such as water, food, disaster-risk reduction, recreation and connections with nature). This study had financial support from FAPERJ through the scholarship Doutorado Nota 10 (‘grade-A PhD student’) and funding on the project “Water: integrating biodiversity and water security in Rio de Janeiro”. Their research group has partnerships with scientific institutes such as Brazilian Foundation of Sustainable Development (FBDS), Brazilian Platform on Biodiversity and Ecosystem Services (BPBES) e Brazilian Network on Global Climate Change (Rede-Clima).
About the research: Nature as a solution for floods in cities
The solution for floods in cities could be simple: Nature-based Solutions aim to solve society problems based on the protection and recovery of natural areas. A recent study reveals that precisely these Nature-based Solutions focused on forest regeneration might be key to considerably reduce flood risk in Rio de Janeiro, Brazil, in face of uncertain future of upcoming climate change.
Floods are among the greatest environmental problems in Rio de Janeiro state. Only in the homonymous capital, more than 450 thousand people live in flood-prone areas. In 2011, floods in the Serrana region mountain-ranges left 35 thousand people homeless and dozens dead, with more than R$8,4 billion in economic losses.
Worrisomely, flood risk in Rio de Janeiro is predicted to skyrocket facing climate change. Beyond considerable increase in the planet’s temperature, climate change will increased the frequency and intensity of precipitation extreme events, rising flood risks.
In the study, the researchers assessed flood risks considering increased extreme events. Surprisingly, without any action, results show that flood risk is not directly proportional to increase in rainwater volume: a maximum extreme event with 10 times greater rain intensity compared to mean levels is translated to increases 70 times greater of flood risks under climate change. This occurs because the city’s rainwater retention capacity falls by more than half, incapable to contain such volume.
However, the study reveals that Nature-based Solutions have a great potential to reduce this risk. The researchers assessed the benefits of different proportions of forest recovery and identified the one with better cost-effectiveness for Rio de Janeiro. The results show that the recovery of only areas with high to medium priority of natural regeneration, where the forest cover would represent only 30% of the state, would provide retention of more than 100 million cubic meters of rainwater.
And the benefits go further. Nature is capable of providing countless additional benefits beyond flood prevention, which greatly surpass the cost to recover forests. The researchers calculated financial benefits of payment for ecosystem services in these areas, and just including a few of them (carbon sequestration, wood production and palm fruit production), the potential benefits surpass implementation and maintenance costs by over R$8 million a year.
Studies on the potential of Nature-based Solutions are essential to promote a future with greater social, economic and natural benefits towards sustainability. The study provides valuable contributions since such are lacking in Brazil, especially in large urban centers, which is the main focus of their research group.