março, 22 2019

Analysis demonstrates a trend in the reduction of the region’s water bodies. On average, 350 km2 of surface freshwater is being lost every year. Alteration of aquatic ecosystems is caused by both human intervention, through the conversion of native vegetation and infrastructure works, and climate change.

By Denise Oliveira

Brasilia, 22 March 2019 - Images of Landsat satellite collected over 33 years (from 1985 to 2017), new data processing technology in computer clouds and dedicated analysis carried out by researchers have led to new observations relating to changes in the Amazon’s water bodies.

Brazil normally focuses on the analysis of annual data relating to the conversion of native vegetation and changes to land ecosystems with Prodes project, which measures the suppression of native vegetation in the Amazon. This new study evaluated transformations to surface freshwater in the Amazon and could pave the way for regular annual monitoring of the region’s water bodies, including rivers, lakes and floodable wetlands.

Current projections are not so positive, however. The analysis carried out by WWF-Brazil and the Man and Environment Institute of Amazonia (Imazon) – as part of the MapBiomas Project and with the support of Google Earth Engine – reveals a trend in the reduction of water surfaces. On average, 350 km² of surface freshwater is being lost every year.

The results of the analysis Long-Term Annual Surface Water Change in the Brazilian Amazon Biome: Potential Links with Deforestation, Infrastructure Development and Climate Change were published on Tuesday, March 19, in a special edition of the scientific publication Water. The article addressing the status of water resources in the Americas brought to light previously unseen data on a scale covering the entire biome. This is the first time that a study of this magnitude has been carried out right across the Amazon biome.


Causes and impacts

Bernardo Caldas, conservation analyst for WWF-Brazil’s Science Program and one of the authors, explains that there is a correlation between the loss of water surface in the Amazon region and the construction of hydroelectric and deforestation.

Human intervention, involving a combination of small hydropower plants, as well as major infrastructure works, weirs, river dams and lake formation for fish farming, all affect the natural dynamics and generate changes to water bodies and water flows that impact the system as a whole. Regions in which human interventions are more pronounced coincide with the zone known as the “deforestation arch” in the southern Amazon.

River dams (which interrupt the natural flow of water) affect flood pulses. The cumulative effects of a series of dams can cause the watercourse to enter collapse and subsequently interfere with the dynamics and ecological services of an entire water basin.
 
The areas most affected by this loss in surface freshwater are the floodplains and lagoons that form from the ebb and flow of the water. The Amazon basin comprises a network of distinct and interlinked aquatic ecosystems. These ecosystems are fundamental for biodiversity, as well as the breeding of fish and other aquatic species.

“The loss of these dynamic habitats, which are influenced by the natural pumping and flow of the water, endangers freshwater dolphins, fish, turtles and many other species that depend on these sites to breed. We are losing the breeding sites where life in the Amazon originates. As a result, the communities that depend on this biodiversity will also be affected,” explains Caldas.

Caldas also emphasises that water does not obey state or national boundaries. Its unit is the water basin, comprising the network of rivers and the natural flow of water.
 
“Strategic environmental macroplanning is required that considers not just larger structures, but also the cumulative impact of thousands of small projects that can affect the environmental services provided by a particular water basin. These services include the supply of water for local populations, animal husbandry, agricultural production, livestock raising, food security, communities, tourism, and the need to ensure ecosystems have the time and space to maintain themselves”, Caldas added.


Challenges

The main challenges involved in carrying out the study included the scale and complexity of the region and the long time period under analysis. 

Carlos Souza, researcher at Man and Environment Institute of Amazonia (Imazon),  explains that the study was only possible thanks to recent technological advancements in the processing of large volumes of data. “We use servers spread throughout the world to process an impressive volume of satellite images. This would have been almost impossible just a few years ago,” he commented.


Next steps

The research is part of a series of studies being performed by WWF-Brazil to analyse the fragmentation of the Amazon’s rivers and the subsequent consequences of this. Developed alongside a range of partners in the region, the purpose of this analysis is to bring together aspects of hydrology and biodiversity to gain a cross-border perspective.
 
This set of studies is enabling the development of public and private strategies to guarantee the sustainable development of the region. An ecologically healthy Amazon that can continue to benefit everyone through products and services from its land and aquatic ecosystems – both locally and globally – is indispensable. These studies currently being developed by WWF-Brazil and its partners are widening our understanding of this complex and fundamental natural system.


Paper:

Long-Term Annual Surface Water Change in the Brazilian Amazon Biome: Potential Links with Deforestation, Infrastructure Development and Climate Change
https://www.mdpi.com/2073-4441/11/3/566/htm