Deforestation, especially in the Andean highlands of Bolivia and Peru, was the main driver of this year’s disastrous flooding in the Madeira river watershed in Bolivia’s Amazon rainforest and the drainage basin across the border, in Brazil.
That is the assessment of Marc Dourojeanni, professor emeritus at the National Agrarian University in Lima, Peru.
His analysis stands in contrast with the views of environmentalists and authorities in Bolivia, who blame the Jirau and Santo Antônio hydroelectric dams built over the border in Brazil for the unprecedented flooding that has plagued the northern Bolivian department or region of Beni.
“That isn’t logical,” Dourojeanni told IPS. Citing the law of gravity and the topography, he pointed out that in this case Brazil would suffer the effects of what happens in Bolivia rather than the other way around – although he did not deny that the dams may have caused many other problems.
The Madeira river (known as the Madera in Bolivia and Peru, which it also runs across) is the biggest tributary of the Amazon river, receiving in its turn water from four large rivers of over 1,000 km in length.
The Madeira river’s watershed covers more than 900,000 square km – similar to the surface area of Venezuela and nearly twice the size of Spain.
In Bolivia, which contains 80 percent of the watershed, two-thirds of the territory receives water that runs into the Madeira from more than 250 rivers, in the form of a funnel that drains into Brazil.
To that vastness is added the steep gradient. Three of the Madeira’s biggest tributaries – the Beni, the Mamoré and the Madre de Dios, which rises in Peru – emerge in the Andes mountains, at 2,800 to 5,500 metres above sea level, and fall to less than 500 metres below sea level in Bolivia’s forested lowlands.
These slopes “were covered by forest 1,000 years ago, but now they’re bare,” largely because of the fires set to clear land for subsistence agriculture, said Dourojeanni, an agronomist and forest engineer who was head of the Inter-American Development Bank’s environment division in the 1990s.
The result: torrential flows of water that flood Bolivia’s lowlands before heading on to Brazil. A large part of the flatlands are floodplains even during times of normal rainfall.
This year, 60 people died and 68,000 families were displaced by the flooding, in a repeat of similar tragedies caused by the El Nińo and La Nińa climate phenomena before the Brazilian dams were built.
Deforestation on the slopes of the Andes between 500 metres above sea level and 3,800 metres above sea level – the tree line – is a huge problem in Bolivia and Peru. But it is not reflected in the official statistics, complained Dourojeanni, who is also the founder of the Peruvian Foundation for the Conservation of Nature, Pronaturaleza.
When the water does not run into barriers as it flows downhill, what happens is “a tsunami on land,” which in the first quarter of the year flooded six Bolivian departments and the Brazilian border state of Rondônia.
The homes of more than 5,000 Brazilian families were flooded when the Madeira river overflowed its banks, especially in Porto Velho, the capital of Rondônia, the state where the two dams are being completed.
For the complete article, please see Inter Press Service.