The growing human demand for energy led to the ‘era’ of the construction of dams, leaving many of the rivers of the world fragmented by these dams. These infrastructures are barriers that isolate biodiversity that inhabit the affected aquatic ecosystems.
The Madeira River basin is a transboundary basin, which spans through parts of Bolivia, Brazil and Peru, and is part of the Amazon River basin, the largest on the planet. The Madeira River is born from the union of the Beni and Mamore rivers, in Bolivia, and has a length of approximately 3240 kilometers to find the Amazon River, in Brazil.
On the Brazilian side, hydroelectric plants of Jirau and Santo Antonio have already been built on the Madeira River. The construction of the Santo Antonio dam was completed in 2012 and is projected to produce 3,568 MW. The Jirau dam, completed in 2014, has a potential production estimated at 3,750 MW.
The impacts of dams on rivers go far beyond the works themselves, because the river damming interferes with water pulses and water flows regime. Furthermore, the disruption of a free flowing river affects all biodiversity.
Some of the environmental impacts which contribute to the continued loss of biodiversity, both in streams and in other local ecosystem, are the reduction or blocking the sediments flow, hindering the migration of fish; the permanent inundation of habitats; or increased water pollution, among others.
Impact studies and monitoring
Studies of Environmental Impact Assessment (EEIA) include the definition of the boundaries of areas of direct and indirect influence (AID and IIA), which are part of the works and projects that affect the environment.
For the delimitation of these areas is considered a combination of environmental and socioeconomic criteria. AID limits only include the areas that are directly affected by the infrastructure of dams and flooded areas. The IIA limits include sub-basins around the dam. In the case, o Madeira River, the IIA does not include Bolivian territory.
WWF-Bolivia has developed, together with other institutions, a Monitoring System that also defined an area of regional studies, which includes the Madeira River basin, on the Brazilian side. This area was established with the objective to determine the cumulative impacts of hydropower projects.
Some impacts may be felt to the headwaters of the Amazon basin in Bolivia at least until the 300msnm – migration area of some fish species that migrate long distances.
The Monitoring System of the impacts of hydroelectric dams of Jirau and Santo Antonio also defined two areas of influence in Bolivia, which are: Area of Direct Influence in Bolivia (AID-B), which are areas that is subject to have changes on flood patterns, and Indirect Influence Area in Bolivia (IIA-B), as the area that will receive indirect impacts of hydroelectric dams.