Course:CONS200/2019/Is hydropower really green? Socio-environmental benefits and downsides of hydropower expansion in the Amazon basin.

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Introduction to Hydropower in the Amazon Basin

Currently, the vast majority of the world’s energy is derived from the burning of fossil fuels such as oil and coal. This process releases harmful greenhouse gases into the atmosphere, which are the largest contributors to climate change. One potential alternative source of energy that is currently gaining leeway is hydropower. Hydropower is derived from hydropower plants which require to be built partially on land and partially in water; canals are built in the water to channel water to the turbines, moving them and generating power from the water's kinetic energy which is processed in the part of the system that was built on land and is transferred elsewhere for use.[1] Hydropower is a renewable alternative source of energy to high carbon-emission options. It is considered renewable because water sources are replenished during the locations’ rain-seasons.[2] However, just because is is renewable does not necessarily mean it is sustainable [3] Hydropower plants require a lot of resources and metals which have to be mined in order to build them. They also take up space in terrestrial and aquatic ecosystems which largely interferes with the local biota. As well as ecological factors, there are also social factors that come into play. All of the pros and cons of hydropower may be observed in Brazil’s current efforts to establish plants in the Amazon River Basin.

Brazil is a growing country with heavily increasing energy needs. [4] The use of hydropower is on the rise in Brazil, accounting for approximately 76% of its energy’s source and there is potential to increase hydropower plants through further installations in the Amazon River [3]. If hydropower plants are installed, more energy will be readily available to consumers, but there will be consequences effecting variables such as health, soil quality, fish spawning, biodiversity, greenhouse gas levels, and even local fishermen. Despite the potential severity of these consequences, there are still possible solutions to limit the negative repercussions.

Categories of Actors

Images from Wikimedia Commons can be embedded easily.

Those positively affected and those negatively affected.

Positively Effected

  • Economy
  • Hydropower Company
  • Architects
  • Engineers
  • Consumers who receive energy from new plants

Negatively Effected

  • Local aquatic biota i.e. fish, snakes
  • Local terrestrial biota i.e. trees, mammals
  • Local tribes
  • Local farmers
  • Local human inhabitants
  • Local Fishermen

The Negative Ecological Impacts of Hydro Power in the Amazon Basin

1. Dam Impacts on Fish Spawning Pathways in the Amazon River

Many different species of fish travel to spawning grounds via rivers, and those who live in the Amazon are no exception.[5] Between the Amazon, Mekong, and Congo, about a third of freshwater fish species are at risk with the input of dams.[5] When a dam is placed in an area, especially one with a high flow-rate, it blocks the path of those fish.[5] Dams tend to be placed in high-flow areas and rapids since those generate the most power for a hydroelectric dam.[5] Unfortunately, many fish species have adapted to swim through these areas, and end up finding their natural life-cycle path obstructed.[5]

2. Soil Impact

When a damn is put into place, it traps the silt that naturally flows downriver.[6] Silt and other necessary agricultural nutrients get trapped by the physical damn.[6] Along with small particles, seeds from tree and plant species are blocked from their usual path of dispersal due to the change in flow patterns of the river from the dam.[6] Soil disruption early in the river restricts flow of genetic material and nutrients for other biota downstream, up to thousands of kilometres away.[7] The resulting loss of vegetation cover will causee a drier climate to take over the Amazon, particularly in the East, which will reduce the amount of water in the river, which will cause adverse effects on the soil.[7]

3. Loss of Biodiversity

Dams are placed in strategic locations where rivers run at an elevation between 200 and 1000 metres and have a relatively steady flow.[7] This causes fast-flow areas to turn into still and slow-moving pools, which changes the environmental niche for many species.[7] The dams are not controlled in a way that takes natural life-cycles of existing biota near them into consideration.[7] The optimal energy production regime causes a change in the natural flood cycle which is an important environmental trigger.[7] Flood pulses alert fish to start their spawning season and plants to start their fruit/seed production.[7] When these natural triggers are subdued, the backlash is felt by local fisherman and animals that survive off these species who roam the river.[7] The biggest risk to Amazonian biodiversity is the lack of knowledge of taxonomy, physiognomy, breeding habits, and seasonal habits of many freshwater species that reside in the Amazon Basin.[7]

4. Spread of Disease

Small populations of people who reside near reservoirs tend to lose access to river water.[8] The natural springs near those populations may also dry up.[8] The adverse effects of hydro power dams is that they take away clean water from small households, leaving communities with unsafe water.[8] Unsafe drinking water leads to many water-borne diseases like schistosomiasis, malaria, encephalitis, hemorrhagic fevers, gastroenteritis, intestinal parasites, and filariasis.[8] Malaria spread has also increased from human influences on the river like dams.[9]

5. Increased Greenhouse Gas Emissions (GHG's)

Often overlooked when counting Greenhouse Gas Emissions, the hydropower dams of the Amazon produce a significant amount of GHG's in the form of Methane.[10] Naturally, decay of a tree is seen as a net-carbon function since the biomass created took in carbon dioxide to grow, and released the same amount when it died.[10] By contrast, those trees that are trapped in reservoirs caused by these damns are left to decay in anoxic conditions.[10] This means that the organic matter left at the bottom of the sediment-filled reservoir will decay with a lack of dissolved oxygen, causing its decay to release methane instead of carbon dioxide.[10] These emissions will be missed by samplers downstream since the gas is immediately released as gas bubbles when the water flows out of the turbines on the other side of the dam.[10]

Socioeconomic Impacts of Hydropower Expansion

For many developing countries, the construction of hydropower dams promises a massive economic boom in the short term, followed by sustained growth, and improvement of socioeconomic factors as a result in the long term. [11] In reality, however, these projects do not result in long term development; as the initial boom fades away, so does the promise of advancing social conditions. [11] The benefits from the boom, (the construction and operation of the hydroelectric dams), is quite brief, especially in contrast with the long lasting impacts which dams and their reservoirs have on the environment, which vastly outlive the socioeconomic gain they provide. [11]

Socioeconomic Indicators

Socioeconomic indicators are an effective way of quantifying socioeconomic status. They include factors such as education, longevity, income, access to electricity and plumbing, and rates of teenage pregnancy and HIV. [11] Comparing the status of these factors in a county after the construction of a hydroelectric dam to a control county with no hydroelectric allows a glimpse into the social effects of the dam. For counties in which a dam was constructed between 2000 and 2010, income is relatively greater, and teenage pregnancy slightly lesser than in the control. [11] However, education, longevity, access to electricity and plumbing, and rates of HIV are either the same as or worse than the control. [11] This goes to show that the economic impact of hydroelectric dams does not necessarily transfer to improved human development benefits, despite increasing incomes.

Impacts on Fishermen

While hydroelectric dams provide new job opportunities and economic growth for those involved in their construction and operation, they also disrupt other economic activities. The construction of dams is a hinderance to fish populations, effecting both reproduction and migration. [12] This disruption to the fish stock influences fishermen economically. In areas where reservoirs are constructed, fishermen are working more and earning less. [13] Average fishing trips per month have increased in areas where dams have been built; this leads to increasing costs for fishermen in the form of fuel, ice, and food. [13] Fishermen also face barriers to selling their fish. [13] When these dams are built, fish die-offs often occur. [13] This leads to a belief that fish from these waters are unsafe to eat, driving down the demand and market price of the fish caught in them. [13] All these changes present significant challenges to fishermen and the fishing industry after a hydroelectric dam is constructed. These changes stress the members of effected communities, leading to an increase in violence and drug use. [13]

Gender Differentiated Impacts

In the Amazon, and elsewhere, women play an important role in the commercial fishing industry. [14] The fishing strategies employed by men and women, their methods of fishing, targeted species, and fishing spots, vary by season among each other. [14] The negative impacts which most concern fishermen and women tend to be different. [14] While fishermen tend to be more concerned about economics, catching the most valuable fish, women tend to be concerned about finding sufficient food to feed their families. [14] Fishermen are travelling further than before in order to catch the most economic fish, and as a result, spending more on fuel and other factors previously mentioned. [13] [14] Women are now catching less fish and spending more of their time performing household duties and relying on the economic support of men, thus reducing female autonomy and increasing domestic burden. [14] The diverse effects that the construction of hydroelectric dams has on fishermen and women influence social dynamics of Amazon communities, further stressing the members of these communities beyond the basic environmental impacts.

Options for remedial action(s)

Possible Solutions for Fisheries

To increase the survival of fish traveling downstream through the hydroelectric dam efficiency is a key factor in survival, with lower efficiency there is more factors present that increase mortality, this includes shear stress, pressure changes, and turbulence [15]. As well switching to newer turbine models such as the MGR and Kaplan runners would also decrease fish mortality as these newer models are designed in a way to minimize gap space between turbine fins and passage walls [15]. This modernization of turbines prevents another large cause of mortality, physical injuries including grinding, slashes and striking. By reducing injures sustained by travelling through the turbines the survival rate of fish populations will be less effected by hydroelectric dams.[15]. This in turn would decrease the effects of hydroelectric dams on down stream fishing operations [15].

Possible Solutions for Green House Gases

Majority of the greenhouse gases come in the form of methane dissolved along the bottom of the reservoir. This becomes an issue due to the hydroelectric dams intake location. Methane concentration increases with depth leading to more methane being drawn into the dam and released into the environment [16]. By introducing a light metal barrier attached to buoys and anchors a physical barrier can be introduced to allow only shallow methane depleted water entering the turbines reducing the amount of methane released into the atmosphere[16] . As well a methane monitoring probe could be installed into a cable system to control the depth of the barrier to ensure methane concentration is maintained at a predetermined level during operation of the dam [16].

Health Impacts

One reason health issues are so prevalent is due to the complexity of the issue. Especially in the tropics where toxins can come from algae blooms, waterborne diseases and heavy metals [17]. As a result of this a solution must be reached through the use of many professionals and not a single person. In this regard one of the best solutions to the health issues a proactive stance in the development stages of the dam [17]. By taking measures to reduce the potentially build up of different disease vectors later issues can be avoided. As well most research done on the health issues of hydroelectric dams focus on a single aspect of disease vectors, poverty, or malnutrition [17]. As a result the health effects of dams are not incorporated into the design or placement of the dam. To combat this further research is needed to allow policy to come into play to create changes in how health is viewed for the construction of hydroelectric dams[17].


One tool that can be used to assess the impacts of hydroelectric dams is the social impact assessment (SIA)[18]. Through the use of this tool we can begin to assess the impacts that the installation of a hydroelectric dam can have one local communities. Through the use of this tool we can begin better understand the impacts that are overlooked by dam construction[18]. One such solution that may arise is the training of local workers to operate the dam, however for this to be effective it must be prioritized and properly funded[18].However this tool is only a baseline and does not always catch certain issues that are cultural in nature[18]. Yet by being able to highlight the issues brought forward regional specific solutions can be created both preemptively and post-construction[18].


Hydropower, though a renewable source of energy, is not necessarily a sustainable one.[19] Relative to burning fossil fuels as a source of energy, it is the lesser of two evils. If hydropower plants are established, there will be direct and indirect severe negative impacts on the local terrestrial and aquatic biota soil quality, human and ecological health, economic impacts, and atmospheric impacts which will broadcast secondary and even tertiary impacts of their own. Though situations involving installed hydropower plants are still too new to fully understand the full effects that these power sources have on ecosystems to draft any definite policy outlining broad environmental protections, there are still minor regulations that may be implemented to reinforce ecosystems. These regulations may include the requirement of removing all debris from canals so that they do not decompose and release excess greenhouse gases into the atmosphere, and the requirement to avoid construction within a certain vicinity of areas that have been flagged as occupied homes for endangered wildlife in an effort to preserve biodiversity.


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Seekiefer (Pinus halepensis) 9months-fromtop.jpg
This conservation resource was created by Will. It is shared under a CC-BY 4.0 International License.