As The Guardian newspaper recently reported, chopping down trees in the Amazon rainforest decreases water supply to distant Sao Paulo, Brazil's most populous city. Large-scale deforestation disrupts the water cycle and can affect weather patterns thousands of miles away. However, the Amazon is not the only forest sustaining the water resources of Sao Paulo. The Atlantic Forest, which stretches across southeast and northeast Brazil and through the watersheds that supply drinking water to Sao Paulo, Rio de Janeiro, Vitoria and several other cities, plays a crucial role in stabilizing local climates, increasing water flow in dry periods, purifying water and creating a buffer against floods.
Saving the Atlantic Forest
Although the Atlantic Forest is not as famous as the Amazon, it is similarly a hotspot for plant and animal life, and has an even more striking history of deforestation. While it historically covered an area larger than Peru, deforestation has claimed all but 12 percent of these forests. Its loss has degraded important water sources for Brazilian metropolitan regions that are home to more than 63 million people.
Restoring this forest can help these regions reap the benefits provided by natural infrastructure:
Climate Control. Similar to the Amazon, the Atlantic Forest influences local hydrology. Its high-altitude cloud forests, which are prominent in coastal mountains in Southeast Brazil, generate water supply in dry periods through " fog capture."
Sedimentation Control. Healthy native Atlantic Forest plants have a complex root structure that holds soil in place, preventing erosion, avoiding soil and nutrient losses, and consequently improving water quality.
Flood Control. The Atlantic Forest acts like a sponge to curb floods during periods of high rainfall and slowly release this water in dry periods to sustain local water supply. This forest function is increasingly important, since southeast Brazil is expected to experience more floods by mid-century due to climate change.
Improved Lives and Livelihoods. Restoring forests can provide jobs and recreation spaces to improve human well-being. If Brazil meets its commitment under the Bonn Challenge to restore 12 million hectares of forest by 2030, 138 to 215 thousands jobs could be created.
SABESP (Sao Paulo's water company) and other water utilities in southeast Brazil unfortunately have limited control over the land use decisions of the Amazon, which is hundreds of miles away. But they can help protect and restore the nearby Atlantic Forest as a proactive water management strategy. SABESP has led the way by conserving more than 45 thousand hectares (over 111 thousand acres) of forest on its own land holdings. However, the need for restoration to recover this forest extends far beyond water companies' own fence lines.
Take, for example, the Cantareira Water Supply System— a watershed located in the Atlantic Forest range, which provides about half the water supply for the Sao Paulo Metropolitan Area. This watershed possesses only 21.5% of its original forest cover, and in general, native forest restoration efforts have been insufficient. SABESP has reforested almost 1200 hectares of forest adjacent to their reservoirs in the Cantareira, but there are most certainly even more water benefits to be gained by reforesting steep slopes, degraded pastures, or other key ecological zones throughout the 228,000-hectare area. There is a huge opportunity to bring back forests here.
Restoration Efforts Need Utility Buy-In
Luckily, there are already many ambitious Atlantic Forest restoration efforts that southeast Brazil's water companies can join. Brazil's Atlantic Forest Restoration Pact has mobilized 260 members—including governments, civil society groups and businesses—committed to restoring 1 million hectares (nearly 2.5 million acres) of forest by 2020, and 15 million hectares (37 million acres) by 2050. The Pact has already commissioned studies on the best places to restore forests to help secure urban water supply. The Nature Conservancy has also taken strides to accelerate Atlantic Forest restoration by establishing three Water Funds in Southeast Brazil, which raise funds from water users to invest in strategic watershed restoration. These programs need strategic partners such as water companies to financially support restoration activities.
Studying the Forest to Save It
While we know that the Atlantic Forest generally provides water benefits that can be harnessed to secure water supply, we need better information to help pinpoint when, where and how much Atlantic Forest to restore to provide the optimal results for water companies. Without this information, water companies may be hesitant to support more ambitious forest restoration efforts.
To address these questions, WRI, The Nature Conservancy, International Union for the Conservation of Nature, Natural Capital Project, Instituto Bioatlantica, Boticario Foundation and FEMSA Foundation have partnered in the cities of Sao Paulo, Rio de Janeiro and Vitoria to examine the business case for water companies to invest in strategic forest restoration efforts. This project, due to publish results next year, will provide guidance to water companies and watershed committees on why, where, and how much to invest in forest restoration as natural infrastructure.
One thing is already certain: until water utilities in southeast Brazil address the need for massive forest restoration in their backyards, they're missing a huge opportunity to improve their water security.