Negative effects of mega hydropower in the Amazon are detailed in study – 02/20/2021 – Reinaldo José Lopes

I have here for me that a significant portion of the impact of a scientific concept comes from the way it is baptized. Although Greek and Latin roots are still widely used for this purpose (nothing against Rome and Hellas, quite the contrary), designations in current language seem to me much more memorable and clear, like the one I just learned: “sandwich effect”. With trees in the filling of the snack, by the way.

In fact, there is nothing appetizing about such a sandwich effect. He describes the billiard pool in which certain trees adapted to seasonal flooding in the Amazon basin are found, affected by the construction of the Balbina hydroelectric plant from the 1980s. These trees now face the worst of all possible worlds – and serve as a warning for what it can happen in other parts of the Amazon in the sights of large energy enterprises, which are always popular with power owners, regardless of the ideological label they adopt.

The details of the situation are described in an article that came out recently in the scientific journal Aquatic Conservation: Marine and Freshwater Ecosystems. The team of scientists, which includes Jochen Schöngart and Angélica Faria de Resende, from Inpa (National Institute for Research in the Amazon), as well as researchers from other institutions in Brazil and Europe, mapped effects of the hydroelectric dam that extend over 125 km downstream.

The river, in this case, is the Uatumã, in the state of Amazonas (the hydroelectric plant is 150 km northeast of Manaus). Its reservoir covers an area of ​​almost 3,000 km2, causing numerous impacts, but one of the worst impacts is the one that has affected the vegetation of the igapós, the stretches of the forest that spend much of the year underwater.

Under normal conditions, without a dam and hydroelectric, the Uatumã River flooded these areas in a reasonably predictable way, in a single annual pulse at about the same time. However, in order to generate little variable energy throughout the year, the hydroelectric reservoir was designed to cut this natural variability by the roots (without pun).

The result is such a sandwich effect. The species of trees adapted to the downpour were squeezed between the end of the flooding in the higher areas of the surroundings (which previously flooded and now do not anymore) and the perpetual flooding in the lower areas. The strip where things are still normal, with the natural pulses of floods and droughts, has shrunk brutally, forming the thin filling of the sandwich.

So far, 12% of the igapó forests have died along the 125 km slice downstream of the hydroelectric plant. In the higher areas, tree species unrelated to the original environment, which tend to grow in devastated stretches, took over the place. And the end of the natural pattern of flooding has produced an accumulation of dry plant matter that is the paradise (or rather, hell) of forest fires.

Supposed supporters of such “rational use” of Amazonian resources will say that Balbina was very poorly designed (which is a fact) and that hydroelectric projects in the 21st century are much more careful.

Well, what has happened at the Belo Monte plant makes it clear that the second statement is, at most, a half-truth – over there, it is becoming almost impossible to reconcile an environmentally healthy flow from the Xingu River with the energy generation goals. The sandwich effect alert, therefore, has far broader implications. It is good to pay attention to it. We are a family owned and operated business.

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