Boca das Tropas, Brazil - Along the peaceful and serene river banks of the Tapajos River - a tributary of the Amazon - a proposed hydroelectric dam has stirred the ire of the villagers living in the area.

"Each day more police arrive in our villages, more armed forces. They think they will intimidate us but they never will. We are fighting for our people, our children, our nature," Rosenilda told Al Jazeera.

As a guerreira - a woman warrior from the 14,000-strong Munduruku tribe - she protects the Boca das Tropas village, a 40-minute boat ride from the town of Jacareacanga.

Not far off, children were chattering and laughing in the Munduruku language as they dived off the river bank. Women, carrying baskets on their backs secured by bands around their foreheads, were cleaning up the centre of their village.

Rosenilda and another guerreira, Maria Leusa, were deadly serious in their determination to oppose, through direct action if necessary, the government's plan to build 12 dams along the Tapajos river valley.

However, many Brazilians believe that the Indians must not be allowed to put their interests above the demands of national development. Claudio Sales, the director of Acende Brasil, an energy think tank, believes that if Brazil is to continue developing, then it must tap into the Amazon's huge hydropower potential.

Speaking to Al Jazeera at a major international energy conference held in Sao Paulo more than 2,000km away from the indigenous village, he said in October 2013: "The government's 10-year energy plan predicts that 19,000 additional megawatts of hydropower will come on stream by 2021. Of this, no fewer than 16,000 megawatts will come from the Amazon. That is how important the region is for us."

Polarised views

People living in the Amazon are divided. Some, like Joao Francisco Vieira, a local councillor in Jacareacanga, view the project favourably. "We need to bring industry to the region and to do this we need hydropower," he told Al Jazeera.

If these dams are built, everything will end. - Lamberto Paina, a local Munduruku tribal chief

"The Indians agree with me. They don't want to go back 500 years [to the time before the arrival of the Portuguese in 1500]. The river flows into the sea - that's what's happening to the Indians. They're evolving."

This may be the position of some of the Munduruku in the towns, but there's strong local opoosition to the dam's construction. According to cacique (a local chief) Lamberto Paina, "If these dams are built, everything will end. That island over there will be flooded. Monkeys, birds, Indians - we'll all lose our homes."

At the beginning of November, 65 caciques met in Restinga. Speaking in the name of their communities, they issued a statement in which they called on the world "to support our movement against the great project of destruction of our planet Earth". Many caciques also complained about the presence of soldiers in their villages. They were sent by the government in order to to protect scientists carrying out environmental impact studies for the dams.

The Indians have allies, some of them powerful figures in the establishment. Felicio Pontes is a prosecutor in the Federal Public Ministry (FPM), an independent state body whose function is to defend the excluded and disenfranchised. He told Al Jazeera that he had repeatedly called for the troops' withdrawal.

He said that, according to the International Labour Organisation's Convention 169, to which Brazil is a signatory, the government should have carried out "a free and informed" consultation with the Indians, known as a "consulta previa", before carrying out the studies. "By militarising the region strongly, the government has broken its dialogue with these populations and made it impossible to carry out a proper consulta previa."

In response, the authorities say that they are carrying out their own consultations, known as "audiencis publicas" (public hearings). Al Jazeera went to one of them, held in Jacareacanga on September 29. The consultation concerned the Sao Manuel dam, planned for the Teles Pires River and a tributary of the Tapajos.

Many of the Munduruku Indians were angry that the meeting was being held, arguing, as does Felicio Pontes, that these hearings involve the entire population as opposed to just the affected populations. From Pontes' standpoint, these meetings should happen only after the consulta previa with the Indians.

A small group of Munduruku Indians, their bodies covered in traditional warfare black paint and armed with bows and arrows and clubs, protested outside the sports stadium where the meeting was held.

Many natural scientists have serious concerns about the proposed energy projects. Although the biologists carrying out the environmental impact studies are banned from talking to the press, one told Al Jazeera that the Tapajos river basin has extreme biological diversity, even by Amazon standards. Of the 1,837 species of birds that occur in Brazil, 613 come from the Tapajos. The area is also abundant in mammalian species, with 161 different species (compared with 222 for the whole of Europe). "We know so little about these species that it's going to be extremely difficult to take effective measures to conserve them," he said.

Possible compromise

Wilson Cabral de Souza Junior, a professor of environmental engineering at Brazil's Technological Institute of Aeronautics (TA), thinks so. He told Al Jazeera that in a recent study his institute had concluded that building dams was not the only, nor the best, solution for generating energy in the Tapajos valley. He added that the big dams were expensive and would make economic sense only if the government provided heavy subsidies.

"It would be far better if the government used the money to develop far less harmful alternatives, mostly in the field of energy conservation and wind and solar energy."

But the time for rethinking the plans is quickly running out. Already one of Munduruku's most sacred sites, regarded by them as a portal to the underworld, has been bulldozed. Fifty Munduruku began an indefinite occupation of a government office in the federal capital, Brasilia in December. They are in no mood to give up the struggle. For them, the very survival of their centuries-old way of life is at stake.