The Importance of Wetlands: The Pantanal

by Duncan Gromko

The Pantanal; Source: NASA WorldWind

Compared to other ecosystem services, the connection between ecosystems and water services can be difficult to understand. It is easy to see how forests provide timber and healthy marine areas provide fish. Even an abstract ecosystem service such as carbon sequestration is becoming more widely understood with the growing profile of forest carbon mechanisms like REDD+. The ways that ecosystems affect water, however, are often hidden, but researchers are making great strides in communicating the benefits of ecosystems to water supplies.

Wetlands play a critical, if under-appreciated  role in water supply. They act as a sort of sponge, soaking up excess water during rainy seasons and slowly releasing it throughout the year. As such, wetlands reduce the risk of flooding and provide continuous water flow during the dry season. They also play an important role in purifying water, by absorbing pollutants. Finally, wetlands reduce erosion and sedimentation in water. The total value of these and other services is estimated at $25,682 per hectare per year for inland wetlands and $193,845 per hectare per year for coastal wetlands. As an example of the value of wetlands, a restoration project invested €86,000 in the rehabilitation of the Manalana wetland in South Africa. The total benefits from restoration amounted to €182,000 and provided each household in the region an extra €297 per year.

Piranha; Source: Magnus Manske

For more reading on wetlands, I recommend the Water and Wetlands report by the Economics of Ecosystems and Biodiversity (TEEB). The report is an excellent summary of the state of wetlands worldwide and the impact that wetlands have on water supply. TEEB Study Leader and UNEP Goodwill Ambassador Pavan Sukhdev emphasized the importance that wetlands have on development: “When we destroy wetlands, we disrupt nature’s water cycle and its ability to provide water of households and farms, so inadvertently we add to the suffering of the poor."

Located in Brazil, Paraguay and Brazil, the Pantanal is the largest wetland in the world at over 140,000 km2. If the Amazon is South America’s water pump, then the Pantanal is its cistern and filtering system. The Pantanal is a giant floodplain, similar to an inland delta. During the wet season of October to March, about 70-80 percent of the Pantanal is flooded. In the dry season, the water leaves via the Paraguay river and eventually into the Paraná river, leaving behind grasslands that support grazing animals.

Here's a cool video about the Pantanal, if a little over-focused on one species. And here's another (with David Attenborough), that I'm not able to embed.

In addition to supporting rich biodiversity, the variability of flooding in the Pantanal serves to protect downstream inhabitants from floods. The peak flood season for the lower Paraná river basin is two to three months earlier than the flood season for the upper Paraguay river. Without the Pantanal, the two flood seasons would be simultaneous, with severe consequences for downstream inhabitants. Conversely, during dry seasons, the Pantanal continuously releases water, meaning that there is more water available downstream when it is needed most. The Pantanal also removes sediments and pollutants, purifying the water for downstream users. The economic value of these services is significant; the Pantanal's water services alone amount to over $13 billion per year.

Here's another video on the Pantanal (half promotional video for WWF).


Climate change, conversion of habitat into agricultural use, and upstream uses of water are the greatest threats to the Pantanal. Agricultural and other development in particular will continue to put pressure on the Pantanal, especially since only 2.6% of the ecosystem is protected by law. As Brazil, Paraguay, and Bolivia make policy and investment decisions for the area, it will be important to protect areas of critical importance. Agricultural productivity is undeniably important, but if it expands into critical areas like the Pantanal, it will ultimately undermine the services that make South American agriculture productive. Water services, in particular, provide significant benefit to those living downstream of this vast ecosystem.

An abbreviated version of this post originally appeared in the IDB Agua Blog on March 22.