535
There has been an unprecedented expansion of hydropower development
throughout the Amazon River Basin, and current plans suggest that the pace of
development is likely to continue (Anderson et al. 2018). Brazil has 256 large dams
in operation or planned, and the country generates nearly 65% of its electricity from
hydropower. The country is home to some of the largest dams in the world, including the 14,000-MW Itaipu Dam on the Paraná River, as well as the controversial
Belo Monte Dam project currently under construction. There is evidence that expansion of hydropower development in the Andean Amazon has been underestimated.
A recent study documented 142 dams in operation or under construction and 160
dams in various stages of planning in Colombia, Ecuador, Peru, and Bolivia
(Anderson et al. 2018). There has been little coordination between these countries
in their hydroelectric planning, and there is growing concern that they are engaged
in a hydropower race where there will be winners and losers. The pace is so fast that
institutions and research organizations can barely meet the requirements of the environmental impact statements required, and where data sharing has been guarded by
the construction companies due to litigation and protests by civil society and ethnic
minorities affected by these dams. The problem is only exacerbated in those cases
taking place near the border areas.
The hydrologic consequences of large-scale dams and reservoirs are extensive,
as humans have appropriated over 50% of the world’s available freshwater runoff,
expected to exceed 70% by 2025. Sharp declines in available freshwater drive
changes in seasonal river discharge, downstream freshwater habitat, loss of floodplains and even coastal erosion and salinity changes. The consequences for ecosystem structure and composition (e.g., habitat fragmentation, loss of aquatic faunal
diversity), and function (e.g., nutrient flows, primary production) are severe.
Reservoirs can also be significant sources of greenhouse gas emissions during bacterial decomposition of flooded peatlands and upland forests (Giles 2006; Fearnside
and Pueyo 2012). Tropical hydroelectric dams, such as those throughout the Amazon
River Basin, emit significant amounts of greenhouse gases, especially methane.
Emissions from tropical hydroelectric dams are often underestimated or ignored in
greenhouse gas accounting, and they can often exceed emissions of fossil fuels for
decades (Fearnside and Pueyo 2012).
The human costs of large dams are also significant, especially for those displaced
by reservoirs are only the most visible victims of large dams. The social, cultural,
economic, and political disruptions of the involuntary resettlement of displaced
populations have costs that are routinely underestimated or ignored (Tortejada et al.
2012; Égré and Senécal 2003). For example, in the Amazon, during the construction
of the Tucuruí Dam in 1989, the area of the reservoir ended up being much larger
than planned, flooded more communities than planned and led to the resettlement of
many more people than originally estimated (Fearnside 1999). Millions more have
lost land and homes to the construction of canals, roads, irrigation projects, and
industrial development that accompany dams. Others have lost access to clean
water, sources of food, and other natural resources in the dammed area. Dams have
also been associated with increases in communicable diseases.
19 Watersheds at the Nexus
There has been an unprecedented expansion of hydropower development
throughout the Amazon River Basin, and current plans suggest that the pace of
development is likely to continue (Anderson et al. 2018). Brazil has 256 large dams
in operation or planned, and the country generates nearly 65% of its electricity from
hydropower. The country is home to some of the largest dams in the world, including the 14,000-MW Itaipu Dam on the Paraná River, as well as the controversial
Belo Monte Dam project currently under construction. There is evidence that expansion of hydropower development in the Andean Amazon has been underestimated.
A recent study documented 142 dams in operation or under construction and 160
dams in various stages of planning in Colombia, Ecuador, Peru, and Bolivia
(Anderson et al. 2018). There has been little coordination between these countries
in their hydroelectric planning, and there is growing concern that they are engaged
in a hydropower race where there will be winners and losers. The pace is so fast that
institutions and research organizations can barely meet the requirements of the environmental impact statements required, and where data sharing has been guarded by
the construction companies due to litigation and protests by civil society and ethnic
minorities affected by these dams. The problem is only exacerbated in those cases
taking place near the border areas.
The hydrologic consequences of large-scale dams and reservoirs are extensive,
as humans have appropriated over 50% of the world’s available freshwater runoff,
expected to exceed 70% by 2025. Sharp declines in available freshwater drive
changes in seasonal river discharge, downstream freshwater habitat, loss of floodplains and even coastal erosion and salinity changes. The consequences for ecosystem structure and composition (e.g., habitat fragmentation, loss of aquatic faunal
diversity), and function (e.g., nutrient flows, primary production) are severe.
Reservoirs can also be significant sources of greenhouse gas emissions during bacterial decomposition of flooded peatlands and upland forests (Giles 2006; Fearnside
and Pueyo 2012). Tropical hydroelectric dams, such as those throughout the Amazon
River Basin, emit significant amounts of greenhouse gases, especially methane.
Emissions from tropical hydroelectric dams are often underestimated or ignored in
greenhouse gas accounting, and they can often exceed emissions of fossil fuels for
decades (Fearnside and Pueyo 2012).
The human costs of large dams are also significant, especially for those displaced
by reservoirs are only the most visible victims of large dams. The social, cultural,
economic, and political disruptions of the involuntary resettlement of displaced
populations have costs that are routinely underestimated or ignored (Tortejada et al.
2012; Égré and Senécal 2003). For example, in the Amazon, during the construction
of the Tucuruí Dam in 1989, the area of the reservoir ended up being much larger
than planned, flooded more communities than planned and led to the resettlement of
many more people than originally estimated (Fearnside 1999). Millions more have
lost land and homes to the construction of canals, roads, irrigation projects, and
industrial development that accompany dams. Others have lost access to clean
water, sources of food, and other natural resources in the dammed area. Dams have
also been associated with increases in communicable diseases.
19 Watersheds at the Nexus