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Annotated Bibliography of Global Deforestation Caused by Dam and Reservoir Construction and Operation
Dams and reservoir construction and operation often involves deforestation, where a forest is cut down that will be submerged by a reservoir. In the U.S., the largest 150 reservoirs submerge of seven million acres of land, much of which was likely deforested. This deforestation releases large amounts of carbon because trees and forests are carbon sinks. The bibliography below offers a global summary of scientific research about deforestation caused by dams and reservoir.
Oliveira, W. L., Medeiros, M. B., Moser, P., & Simon, M. F. (2021b). Mega-dams and extreme rainfall: Disentangling the drivers of extensive impacts of a large flooding event on Amazon Forests. PLOS ONE, 16(2), e0245991. https://doi.org/10.1371/journal.pone.0245991
Extreme weather events and the presence of mega-hydroelectric dams, when combined, present an emerging threat to natural habitats in the Amazon region. To understand the magnitude of these impacts, we used remote sensing data to assess forest loss in areas affected by the extreme 2014 flood in the entire Madeira River basin, the location of two mega-dams. In addition, forest plots (26 ha) were monitored between 2011 and 2015 (14,328 trees) in order to evaluate changes in tree mortality, aboveground biomass (AGB), species composition and community structure around the Jirau reservoir (distance between plots varies from 1 to 80 km). We showed that the mega-dams were the main driver of tree mortality in Madeira basin forests after the 2014 extreme flood. Forest loss in the areas surrounding the reservoirs was 56 km2 in Santo Antônio, 190 km2 in Jirau (7.4–9.2% of the forest cover before flooding), and 79.9% above that predicted in environmental impact assessments. We also show that climatic anomalies, albeit with much smaller impact than that created by the mega-dams, resulted in forest loss along different Madeira sub-basins not affected by dams (34–173 km2; 0.5–1.7%). The impact of flooding was greater in várzea and transitional forests, resulting in high rates of tree mortality (88–100%), AGB decrease (89–100%), and reduction of species richness (78–100%). Conversely, campinarana forests were more flood-tolerant with a slight decrease in species richness (6%) and similar AGB after flooding. Taking together satellite and field measurements, we estimate that the 2014 flood event in the Madeira basin resulted in 8.81–12.47 ∙ 106 tons of dead biomass. Environmental impact studies required for environmental licensing of mega-dams by governmental agencies should consider the increasing trend of climatic anomalies and the high vulnerability of different habitats to minimize the serious impacts of dams on Amazonian biodiversity and carbon stocks.
Swanson, A. C., & Bohlman, S. (2021). Cumulative impacts of land cover change and dams on the land–water interface of the tocantins river. Frontiers in Environmental Science, 9. https://doi.org/10.3389/fenvs.2021.662904
“Riparian vegetation performs important ecosystems services, improving water quality, mitigating erosion, and maintaining regional plant and animal biodiversity. Regular annual flooding maintains riparian forests through an intermediate disturbance regime. In response, seasonally flooded vegetation has developed adaptations for seed dispersal and gas transfer to survive and reproduce while undergoing periods of flooding. In the Amazon, a dam building boom threatens the integrity of riparian vegetation by moving riparian corridors into dry-adapted ecosystems and reducing downstream flooding of riparian areas. Additionally, the region is undergoing intense development pressure resulting in the conversion of native riparian vegetation into agriculture. In this study, we measure how the installation of six large dams on the Tocantins River, coupled with land cover change from native forest and savanna to cattle pasture, has changed the land–water interface of this region. Using land cover data provided by MapBiomas, we quantified land cover change from 1985 to 2018 and measured changes in the riparian areas of the still free-flowing areas of the Tocantins River, riparian areas surrounding reservoirs, and in-stream vegetation dynamics. We found that deforestation in the riparian areas of the Tocantins River downstream of the dams is occurring at a higher rate than deforestation in the watershed. Additionally, reservoir filling resulted in creating hundreds of square kilometers of new riparian areas, pushing the riparian zone away from forest-dominated ecosystems into savanna-dominated areas. The quantity of in-stream vegetation throughout the study was dynamic and initially increased after damming before declining for the last decade of the study. Changes to native land cover in riparian areas of the Tocantins River threaten the integrity of ecosystem services provided by riparian vegetation and are likely to lead to further degradation of these areas
Gordesky, Ben (2021), The True Costs of Hydro Quebec, Bennington Banner.
“Unfortunately, this failure to provide an accurate accounting of environmental harms caused by Hydro Quebec extends beyond greenhouse gas emissions to violations of Indigenous land sovereignty. Hydro Quebec operates more than 550 dams and dikes which flood more than 6,000 square miles of territory. Thirty-six percent of the total hydroelectric power installed by Hydro Quebec was built on First Nation’s land, without compensation or consent. These flooded rivers have decimated hunting and fishing traditions, forced the relocation of entire villages, and caused dangerously high levels of mercury exposure.”
Sentinel Digital Desk, (2021) Bhutan’s New Hydropower Policy. https://www.sentinelassam.com/editorial/bhutans-new-hydropower-policy-535160
“Bhutan’s National Forest Policy Goals call for managing forest resources and biodiversity sustainability to produce a wide range of social, economic, and environmental goods and services for the equitable benefit of all citizens and natural environment while still maintaining a minimum of 60 per cent of the land under forest cover thereby contributing to Gross National Happiness. Balancing the goal of 60 per cent land under forest cover and pursuing the hydropower goal will be a monumental challenge for the Himalayan country. Conservation of forest and environment in Bhutan is critical to entire Himalayan landscape and a mismatch of these two national goals will increase climate change vulnerability in the entire region including Assam and Arunachal Pradesh.”
FAO. 2020. Global Forest Resources Assessment 2020: Main report. Rome.
“The global forest area continues to shrink – by an average of 4.7 million ha per year. Globally, the rate of net forest loss has declined since the 1990s, but the latest data show that the pace of this decline slowed in the most recent ten-year period, mainly because the forest area in Asia and Europe expanded less than in the previous decade. Given the current global trend of a shrinking net forest area, it is unlikely that the Global Forest Goal of increasing the world’s forest area by 3 percent will be met by 2030. Halting deforestation remains a challenge. Deforestation continues, albeit at a lower rate than in the past. In the most recent five-year period (2015–2020), deforestation occurred at a rate of 10 million ha per year – 2 million ha less per year than in 2010–2015. At this rate of reduction, however, achieving the SDG 15 target of halting deforestation will take another 25 years.”
Guerrero, J. V. R., Escobar-Silva, E. V., Chaves, M. E. D., Mataveli, G. A. V., Bourscheidt, V., de Oliveira, G., Picoli, M. C. A., Shimabukuro, Y. E., & Moschini, L. E. (2020). Assessing Land Use and Land Cover Changes in the direct influence zone of the Braço Norte Hydropower Complex, Brazilian Zmazonia. Forests, 11(9), 988. https://doi.org/10.3390/f11090988
Over the decades, hydropower complexes have been built in several hydrographic basins of Brazil including the Amazon region. Therefore, it is important to understand the effects of these constructions on the environment and local communities. This work presents a land use and land cover change temporal analysis considering a 33-year period (1985–2018) in the direct influence zone of the Braço Norte Hydropower Complex, Brazilian Amazonia, using the Collection 4.1 level 3 of the freely available MapBiomas dataset. Additionally, we have assessed the Brazilian Amazon large-scale deforestation process acting as a land use and land cover change driver in the study area. Our findings show that the most impacted land cover was forest formation (from 414 km2 to 287 km2, a reduction of 69%), which primarily shifted into pasturelands (increase of 664%, from 40 km2 to 299 km2). The construction of the hydropower complex also triggered indirect impacts such as the presence of urban areas in 2018 and the consequent increased local demand for crops. Together with the ongoing large-scale Amazonian deforestation process, the construction of the complex has intensified changes in the study area as 56.42% of the pixels were changed between 1985 and 2018. This indicates the importance of accurate economic and environmental impact studies for assessing social and environmental consequences of future construction in this unique region. Our results reveal the need for adopting special policies to minimize the impact of these constructions, for example, the creation of Protected Areas and the definition of locally-adjusted parameters for the ecological-economic zoning considering environmental and social circumstances derived from the local actors that depend on the natural environment to subsist such as indigenous peoples, riverine population, and artisanal fishermen.
Lohani, Sapana; Dilts, Thomas E.; Weisberg, Peter J.; Null, Sarah E.; Hogan, Zeb S. (2020). Rapidly Accelerating Deforestation in Cambodia’s Mekong River Basin: A Comparative Analysis of Spatial Patterns and Drivers, Water 12, no. 8: 2191. https://doi.org/10.3390/w12082191
“The Mekong River is a globally important river system, known for its unique flood pulse hydrology, ecological productivity, and biodiversity. Flooded forests provide critical terrestrial nutrient inputs and habitat to support aquatic species. However, the Mekong River is under threat from anthropogenic stressors, including deforestation from land cultivation and urbanization, and dam construction that inundates forests and encourages road development. This study investigated spatio-temporal patterns of deforestation in Cambodia and portions of neighboring Laos and Vietnam that form the Srepok–Sesan–Sekong watershed. A random forest model predicted tree cover change over a 25-year period (1993–2017) using the Landsat satellite archive. Then, a statistical predictive deforestation model was developed using annual-resolution predictors such as land-cover change, hydropower development, forest fragmentation, and socio-economic, topo-edaphic and climatic predictors. The results show that almost 19% of primary forest (nearly 24,000 km2) was lost, with more deforestation in floodplain (31%) than upland (18%) areas. Our results corroborate studies showing extremely high rates of deforestation in Cambodia. Given the rapidly accelerating deforestation rates, even in protected areas and community forests, influenced by a growing population and economy and extreme poverty, our study highlights landscape features indicating an increased risk of future deforestation, supporting a spatial framework for future conservation and mitigation efforts. “
Velastegui-Montoya, A.; Lima, A.d.; Adami, M. Multitemporal Analysis of Deforestation in Response to the Construction of the Tucuruí Dam. ISPRS Int. J. Geo-Inf. 2020, 9, 583. https://doi.org/10.3390/ijgi9100583
The expansion of hydroelectric dams that is planned, and under construction, in the Amazon basin is a proposal to generate “clean” energy, with the purposes of meeting the regional energy demand, and the insertion of Brazil into the international economic market. However, this type of megaproject can change the dynamics of natural ecosystems. In the present article, the spatiotemporal patterns of deforestation according to distance from the reservoir in the vicinity of the lake of Tucuruí, and within a radius of 30 km from it, are analyzed. A linear spectral mixture model of segmented Landsat-thematic mapper (TM), enhanced thematic mapper plus (ETM+), and operational land imager (OLI) images, and proximity analysis were used for the mapping of the land-cover classes in the vicinity of the artificial lake of Tucuruí. Likewise, landscape metrics were determined with the purpose of quantifying the reduction of primary forest, as a mechanism of loss of ecosystem services in the region. These methods were also used for the evaluation of the influence of the distance from the reservoir on the expansion of anthropogenic activities. This methodology was used for the scenarios of pre-inauguration, completion of phase I, beginning of construction phase II, full completion of the Tucuruí hydroelectric project, and the current scenario of the region. The results showed that the highest deforestation rate occurred in the first period of the analysis, due to the areas submerged by the reservoir and due to the anthropogenic disturbances, such as timber extraction, road construction, and the conversion of forests into large areas of agribusiness.
Rocha, M., Assis, R. L., Piedade, M. T. F., Feitosa, Y. O., Householder, J. E., Lobo, G. de S., Demarchi, L. O., Albuquerque, B. W., Quaresma, A. C., Ramos, J. F., Schöngart, J., & Wittmann, F. (2019). Thirty years after Balbina Dam: Diversity and floristic composition of the downstream floodplain forest, Central Amazon, Brazil. Ecohydrology, 12(8). https://doi.org/10.1002/eco.2144
The construction of hydroelectric dams causes changes in the diversity and floristic composition of floodplain forests due to the irregularity of the hydrological regime in rivers downstream from the dams. In the Amazon Basin, plans for the construction of dams are threatening the igapós, forests flooded by blackwater rivers. In these floodplains, the distribution of tree species is synchronized with periodic flood events of the topographic gradient. Previous studies on the Balbina Dam show an altered flood pulse downstream. This work discusses the potential long-term impacts on the diversity and floristic composition of an igapó downstream of the dam (Uatumã River) and compares it with an area unaffected by the dam (Abacate River). An evaluation of the vegetation strata—adults, saplings, and seedlings—showed that for all strata, diversity was greater in the high igapó (higher topographies) in the Uatumã area. This may be due to the near-total absence of flooding in the high igapó and to the extent of flooding in the low igapó (low topographies). Thus, in the Uatumã area, seeds of species typical of flooded areas cannot reach the high igapó by water and, thus, tend to be replaced by upland forest species (mainly seedlings). In the low igapó, the typical species have difficulty establishing. Therefore, the Uatumã vegetation forms two different communities, which does not occur in the Abacate area. These effects of the dam led to irreversible changes in the diversity and floristic composition across all strata throughout the entire topography in the downstream region.
Grossman, Daniel, (2019) Deliberate drowning of Brazil’s rainforest is worsening climate change. https://www.newscientist.com/article/mg24332480-200-deliberate-drowning-of-brazils-rainforest-is-worsening-climate-change/#ixzz71wilsRx9
“It isn’t just Bolsonaro and the fires. Hydroelectric dams in the Amazon are submerging millions of trees, transforming huge carbon sinks into sources of planet-warming gases.”
Resende AFd, Schöngart J, Streher AS, Ferreira-Ferreira J, Piedade MTF, et al. (2019) Massive tree mortality from flood pulse disturbances in Amazonian floodplain forests: The collateral effects of hydropower production. Science of the Total Environment 659: 587–598. pmid:31096388
Large dams built for hydroelectric power generation alter the hydrology of rivers, attenuating the flood pulse downstream of the dam and impacting riparian and floodplain ecosystems. The present work mapped black-water floodplain forests (igapó) downstream of the Balbina Reservoir, which was created between 1983 and 1987 by damming the Uatumã River in the Central Amazon basin. We apply remote sensing methods to detect tree mortality resulting from hydrological changes, based on analysis of 56 ALOS/PALSAR synthetic aperture radar images acquired at different flood levels between 2006 and 2011. Our application of object-based image analysis (OBIA) methods and the random forests supervised classification algorithm yielded an overall accuracy of 87.2%. A total of 9800 km2 of igapó forests were mapped along the entire river downstream of the dam, but forest mortality was only observed below the first 49 km downstream, after the Morena rapids, along an 80-km river stretch. In total, 12% of the floodplain forest died within this stretch. We also detected that 29% of the remaining living igapó forest may be presently undergoing mortality. Furthermore, this large loss does not include the entirety of lost igapó forests downstream of the dam; areas which are now above current maximum flooding heights are no longer floodable and do not show on our mapping but will likely transition over time to upland forest species composition and dynamics, also characteristic of igapó loss. Our results show that floodplain forests are extremely sensitive to long-term downstream hydrological changes and disturbances resulting from the disruption of the natural flood pulse. Brazilian hydropower regulations should require that Amazon dam operations ensure the simulation of the natural flood-pulse, despite losses in energy production, to preserve the integrity of floodplain forest ecosystems and to mitigate impacts for the riverine populations.
Curtis, P., et al. (2018) Classifying drivers of global forest loss, Science 14, Vol. 361, Issue 6407, pp. 1108-1111. DOI: 10.1126/science.aau3445
“Categories were assigned according to dominant disturbance type (Fig. 1), with each representing a different forest and land use dynamic: (i) commodity-driven deforestation, defined by the long-term, nent conversion of forest and shrubland to a nonforest land use such as agriculture (including oil palm), mining, or energy infrastructure;..”
Da Silva, O.M., Jr., M.A. Dos Santos, L.s. Dos Santos, (2018) Spatiotemporal patterns of deforestation in response to the building of the Belo Monte hydroelectric plant in the Amazon basin. Interciencia 43(2):80-84
The environmental impacts caused by the construction of hydroelectric projects are repeated throughout the literature. When poorly planned, these projects can stimulate activities that degrade the environment and can cause or stimulate deforestation around reservoirs. This paper analyzes deforestation around the Belo Monte hydroelectric plant, in the state of Pará, Brazil. The patterns found show that deforestation had a sudden increase in the year of construction of the plant (2011), presenting an increasing pattern between 2012 to 2015. It was observed that deforestation was concentrated near roads and outside areas of restricted use. The increase in deforestation demonstrates the need to adopt instruments to minimize this impact, with the creation of areas with legal protection among them.
Strand, J., Soares-Filho, B., Costa, M.H. et al. Spatially explicit valuation of the Brazilian Amazon Forest’s Ecosystem Services. Nat Sustain 1, 657–664 (2018). https://doi.org/10.1038/s41893-018-0175-0
The Brazilian Amazon forest is tremendously important for its ecosystem services but attribution of economically measurable values remains scarce. Mapping these values is essential for designing conservation strategies that suitably combine regional forest protection with sustainable forest use. We estimate spatially explicit economic values for a range of ecosystem services provided by the Brazilian Amazon forest, including food production (Brazil nut), raw material provision (rubber and timber), greenhouse gas mitigation (CO2 emissions) and climate regulation (rent losses to soybean, beef and hydroelectricity production due to reduced rainfall). Our work also includes the mapping of biodiversity resources and of rent losses to timber production by fire-induced degradation. Highest values range from US$56.72 ± 10 ha−1 yr−1 to US$737 ± 134 ha−1 yr−1 but are restricted to only 12% of the remaining forest. Our results, presented on a web platform, identify regions where high ecosystem services values cluster together as potential information to support decision-making.
Arantes, CC, Winemiller, KO, Petrere, M, Castello, L, Hess, LL, Freitas, CEC. Relationships between forest cover and fish diversity in the Amazon River floodplain. J Appl Ecol. 2018; 55: 386– 395. https://doi.org/10.1111/1365-2664.12967
Habitat degradation leads to biodiversity loss and concomitant changes in ecosystem processes. Tropical river floodplains are highly threatened by land cover changes and support high biodiversity and important ecosystem services, but the extent to which changes in floodplain land cover affect fish biodiversity remains unknown.
We combined fish and environmental data collected in situ and satellite-mapped landscape features to evaluate how fish species with different ecological strategies and assemblage structures respond to deforestation in floodplains of the Amazon River. We surveyed 462 floodplain habitats distributed along a gradient of land cover, from largely forested to severely deforested. Rather than analyse only taxonomic metrics, we employed an integrative approach that simultaneously considers different aspects of fish biodiversity (i.e. β diversity and taxonomic and functional assemblage structure) to facilitate mechanistic interpretations of the influence of land cover.
Spatial patterns of fish biodiversity in the Amazon River floodplain were strongly associated with forest cover as well as local environmental conditions linked to landscape gradients. Several species and functional groups defined by life-history, feeding, swimming/microhabitat-use strategies were positively associated with forest cover. Other species, including some that would usually be considered habitat generalists and species directly dependent on autochthonous resources (e.g. planktivores), were most common in areas dominated by herbaceous vegetation or open water habitats associated with the opposite extreme of the forest cover gradient. β diversity and the degree of uniqueness of species combinations within habitats were also positively associated with forest cover.
Synthesis and applications. Our results demonstrating that spatial patterns of fish biodiversity are associated with forest cover, indicate that deforestation of floodplains of the Amazon River results in spatial homogenization of fish assemblages and reduced functional diversity at both local and regional scales. Floodplains world-wide have undergone major land cover changes, with forest loss projected to increase during the next decades. Conserving fish diversity in these ecosystems requires protecting mosaics of both aquatic habitats and floodplain vegetation, with sufficient forest cover being critically important.
Cochrane, S. M. V., Matricardi, E. A. T., Numata, I., and Lefebvre, P. A. (2017). Landsat-based analysis of mega dam flooding impacts in the Amazon compared to associated environmental impact assessments: upper Madeira river example 2006–2015. Remote Sens. Appl. Soc. Environ. 7, 1–8. doi: 10.1016/j.rsase.2017.04.005
Hundreds of dams are currently under construction or have been built in the Brazilian Amazon with the purpose of fueling social development via hydroelectric power and the transport of goods along rivers. However, many times the environmental impact assessments used to approve these projects have omitted or grossly underestimated the impacts of these dams, leading to severe and often irreparable damage. As such we conducted a case study of the Santo Antônio and Jirau mega dams on the Madeira River in Rondônia, Brazil and used Landsat TM and OLI data to determine area covered by water along a 539 km stretch of the Madeira River from 2006 to 2015 (covering before and after the dams’ construction). The classification method used in this study was modified based off of previous methods and provided a highly accurate water classification suggesting it to be a valuable way of accurately classifying water along with other land cover classes. We compared the water areas calculated from Landsat land cover maps to the environmental impact assessment estimations used to approve the dams’ construction. This analysis showed the reservoirs to be at least 341 km2 (64.5%) larger than predicted with an additional 102 km2 of unpredicted flooding outside of the planned reservoir areas and 160 km2 more natural forest flooded than expected.
Fletcher, K and Gartner, T., (2017) 3 Surprising Ways Water Depends on Healthy Forests, Global Forest Watch Blog. https://www.globalforestwatch.org/blog/commodities/3-surprising-ways-water-depends-on-healthy-forests/
Latrubesse, E., Arima, E., Dunne, T. et al. Damming the rivers of the Amazon basin. Nature 546, 363–369 (2017). https://doi.org/10.1038/nature22333
“More than a hundred hydropower dams have already been built in the Amazon basin and numerous proposals for further dam constructions are under consideration. The accumulated negative environmental effects of existing dams and proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will affect the Amazon basin’s floodplains, estuary and sediment plume. We introduce a Dam Environmental Vulnerability Index to quantify the current and potential impacts of dams in the basin. The scale of foreseeable environmental degradation indicates the need for collective action among nations and states to avoid cumulative, far-reaching impacts. We suggest institutional innovations to assess and avoid the likely impoverishment of Amazon rivers.”
Langerwisch, F., Walz, A., Rammig, A., Tietjen, B., Thonicke, K., and Cramer, W.: Deforestation in Amazonia impacts riverine carbon dynamics, Earth Syst. Dynam., 7, 953–968, https://doi.org/10.5194/esd-7-953-2016, 2016.
Fluxes of organic and inorganic carbon within the Amazon basin are considerably controlled by annual flooding, which triggers the export of terrigenous organic material to the river and ultimately to the Atlantic Ocean. The amount of carbon imported to the river and the further conversion, transport and export of it depend on temperature, atmospheric CO2, terrestrial productivity and carbon storage, as well as discharge. Both terrestrial productivity and discharge are influenced by climate and land use change. The coupled LPJmL and RivCM model system (Langerwisch et al., 2016) has been applied to assess the combined impacts of climate and land use change on the Amazon riverine carbon dynamics. Vegetation dynamics (in LPJmL) as well as export and conversion of terrigenous carbon to and within the river (RivCM) are included. The model system has been applied for the years 1901 to 2099 under two deforestation scenarios and with climate forcing of three SRES emission scenarios, each for five climate models. We find that high deforestation (business-as-usual scenario) will strongly decrease (locally by up to 90 %) riverine particulate and dissolved organic carbon amount until the end of the current century. At the same time, increase in discharge leaves net carbon transport during the first decades of the century roughly unchanged only if a sufficient area is still forested. After 2050 the amount of transported carbon will decrease drastically. In contrast to that, increased temperature and atmospheric CO2 concentration determine the amount of riverine inorganic carbon stored in the Amazon basin. Higher atmospheric CO2 concentrations increase riverine inorganic carbon amount by up to 20 % (SRES A2). The changes in riverine carbon fluxes have direct effects on carbon export, either to the atmosphere via outgassing or to the Atlantic Ocean via discharge. The outgassed carbon will increase slightly in the Amazon basin, but can be regionally reduced by up to 60 % due to deforestation. The discharge of organic carbon to the ocean will be reduced by about 40 % under the most severe deforestation and climate change scenario. These changes would have local and regional consequences on the carbon balance and habitat characteristics in the Amazon basin itself as well as in the adjacent Atlantic Ocean.
Lees, A. C., Peres, C. A., Fearnside, P. M., Schneider, M., and Zuanon, J. A. S. (2016). Hydropower and the future of Amazonian biodiversity. Biodivers. Conserv. 25, 451–466. doi: 10.1007/s10531-016-1072-3
In an effort to ensure energy independence and exploit mineral resources, the governments of Amazonian countries are embarking on a major dam building drive on the basin’s rivers, with 191 dams finished and a further 246 planned or under construction. This rush to harvest the basin’s vast renewable energy capacity has come without proper consideration of the likely negative environmental externalities on the world’s most speciose freshwater and terrestrial biotas. Here we highlight the economic drivers for hydropower development and review the literature to summarise the impacts of dam building on Amazonian biodiversity.We identify both direct and indirect impacts through the anticipated loss, fragmentation and degradation of riparian habitats. We then propose a series of measures to assess, curb and mitigate the impacts of destructive dams on Amazonian biodiversity.
Locatelli, P., (2015) PARTNER POST: The Amazon Rots Away in New Hydroelectric Power Plant Reservoir, Global Forest Watch Blog.
“The Teles Pires power plant violated its environmental plan and flooded the dam reservoir without clearing vegetation. The resulting decomposition will release large amounts of methane, a greenhouse gas at least 20 times stronger than carbon dioxide at trapping heat.”
Gang Chen, Ryan P. Powers, Luis M.T. de Carvalho, Brice Mora, (2015) Spatiotemporal patterns of tropical deforestation and forest degradation in response to the operation of the Tucuruí hydroelectric dam in the Amazon basin, Applied Geography, Volume 63,Pages 1-8, https://doi.org/10.1016/j.apgeog.2015.06.001.
“The planned construction of hundreds of hydroelectric dams in the Amazon basin has the potential to provide invaluable ‘clean’ energy resources for aiding in securing future regional energy needs and continued economic growth. These mega-structures, however, directly and indirectly interfere with natural ecosystem dynamics, and can cause noticeable tree loss. To improve our understanding of how hydroelectric dams affect the surrounding spatiotemporal patterns of forest disturbances, this case study integrated remote sensing spectral mixture analysis, GIS proximity analysis and statistical hypothesis testing to extract and evaluate spatially-explicit patterns of deforestation (clearing of entire forest patch) and forest degradation (reduced tree density) in the 80,000 km2 neighborhoods of the Brazil’s Tucuruí Dam, the first large-scale hydroelectric project in the Amazon region, over a period of 25 years from 1988 to 2013. Results show that the average rates of deforestation were consistent during the first three time periods 1988–1995 (620 km2 per year), 1995–2001 (591 km2 per year), and 2001–2008 (660 km2 per year). However, such rate dramatically fell to half of historical levels after 2008, possibly reflecting the 2008 global economic crisis and enforcement of the Brazilian Law of Environmental Crimes. The rate of forest degradation was relatively stable from 1988 to 2013 and, on average, was 17.8% of the rate of deforestation. Deforestation and forest degradation were found to follow similar spatial patterns across the dam neighborhoods, upstream reaches or downstream reaches at the distances of 5 km–80 km, suggesting that small and large-scale forest disturbances may have been influencing each other in the vicinity of the dam. We further found that the neighborhoods of the Tucuruí Dam and the upstream region experienced similar degrees of canopy loss. Such loss was mainly attributed to the fast expansion of the Tucuruí town, and the intensive logging activities alongside major roads in the upstream reservoir region. In contrast, a significantly lower level of forest disturbance was discovered in the downstream region.”
Kahn, James R., Carlos E. Freitas, and Miguel Petrere. 2014. “False Shades of Green: The Case of Brazilian Amazonian Hydropower” Energies 7, no. 9: 6063-6082. https://doi.org/10.3390/en7096063
The Federal Government of Brazil has ambitious plans to build a system of 58 additional hydroelectric dams in the Brazilian Amazon, with Hundreds of additional dams planned for other countries in the watershed. Although hydropower is often billed as clean energy, we argue that the environmental impacts of this project are likely to be large, and will result in substantial loss of biodiversity, as well as changes in the flows of ecological services. Moreover, the projects will generate significant greenhouse gas emissions from deforestation and decay of organic matter in the reservoirs. These emissions are equivalent to the five years of emissions that would be generated by gas powered plants of equivalent capacity. In addition, we examine the economic benefits of the hydropower in comparison to new alternatives, such as photovoltaic energy and wind power. We find that current costs of hydropower exceed alternatives, and the costs of costs of these alternatives are likely to fall substantially below those of hydropower, while the environmental damages from the dams will be extensive and irreversible.
Lima, L.S., Coe, M.T., Soares Filho, B.S. et al.(2014) Feedbacks between deforestation, climate, and hydrology in the Southwestern Amazon: implications for the provision of ecosystem services. Landscape Ecol 29, 261–274. https://doi.org/10.1007/s10980-013-9962-1
Forests, through the regulation of regional water balances, provide a number of ecosystem services, including water for agriculture, hydroelectric power generation, navigation, industry, fisheries, and human consumption. Large-scale deforestation triggers complex non-linear interactions between the atmosphere and biosphere, which may impair such important ecosystem services. This is the case for the Southwestern Amazon, where three important river basins (Juruá, Purus, and Madeira) are undergoing significant land-use changes. Here, we investigate the potential impacts of deforestation throughout the Amazon on the seasonal and annual water balances of these river basins using coupled climatic and hydrologic models under several deforestation scenarios. Simulations without climate response to deforestation show an increase in river discharge proportional to the area deforested in each basin, whereas those with climate response produce progressive reductions in mean annual precipitation over all three basins. In this case, deforestation decreases the mean annual discharge of the Juruá and Purus rivers, but increases that of the Madeira, because the deforestation-induced reduction in evapotranspiration is large enough to increase runoff and thus offset the reduction in precipitation. The effects of Amazon deforestation on river discharge are scale-dependent and vary across and within river basins. Reduction in precipitation due to deforestation is most severe at the end of the dry season. As a result, deforestation increases the dry-season length and the seasonal amplitude of water flow. These effects may aggravate the economic losses from large droughts and floods, such as those experienced in recent years (2005, 2010 and 2009, 2012, respectively).
Claudia M. Stickler, Michael T. Coe, Marcos H. Costa, Daniel C. Nepstad, David G. McGrath, Livia C. P. Dias, Hermann O. Rodrigues, Britaldo S. Soares-Filho, (2013), Hydropower energy generation dependence on forests Proceedings of the National Academy of Sciences Jun 2013, 110 (23) 9601-9606; DOI: 10.1073/pnas.1215331110
Tropical rainforest regions have large hydropower generation potential that figures prominently in many nations’ energy growth strategies. Feasibility studies of hydropower plants typically ignore the effect of future deforestation or assume that deforestation will have a positive effect on river discharge and energy generation resulting from declines in evapotranspiration (ET) associated with forest conversion. Forest loss can also reduce river discharge, however, by inhibiting rainfall. We used land use, hydrological, and climate models to examine the local “direct” effects (through changes in ET within the watershed) and the potential regional “indirect” effects (through changes in rainfall) of deforestation on river discharge and energy generation potential for the Belo Monte energy complex, one of the world’s largest hydropower plants that is currently under construction on the Xingu River in the eastern Amazon. In the absence of indirect effects of deforestation, simulated deforestation of 20% and 40% within the Xingu River basin increased discharge by 4–8% and 10–12%, with similar increases in energy generation. When indirect effects were considered, deforestation of the Amazon region inhibited rainfall within the Xingu Basin, counterbalancing declines in ET and decreasing discharge by 6–36%. Under business-as-usual projections of forest loss for 2050 (40%), simulated power generation declined to only 25% of maximum plant output and 60% of the industry’s own projections. Like other energy sources, hydropower plants present large social and environmental costs. Their reliability as energy sources, however, must take into account their dependence on forests.
Finer M, Jenkins CN (2012) Proliferation of Hydroelectric Dams in the Andean Amazon and Implications for Andes-Amazon Connectivity. PLOS ONE 7(4): e35126. https://doi.org/10.1371/journal.pone.0035126
Due to rising energy demands and abundant untapped potential, hydropower projects are rapidly increasing in the Neotropics. This is especially true in the wet and rugged Andean Amazon, where regional governments are prioritizing new hydroelectric dams as the centerpiece of long-term energy plans. However, the current planning for hydropower lacks adequate regional and basin-scale assessment of potential ecological impacts. This lack of strategic planning is particularly problematic given the intimate link between the Andes and Amazonian flood plain, together one of the most species rich zones on Earth. We examined the potential ecological impacts, in terms of river connectivity and forest loss, of the planned proliferation of hydroelectric dams across all Andean tributaries of the Amazon River. Considering data on the full portfolios of existing and planned dams, along with data on roads and transmission line systems, we developed a new conceptual framework to estimate the relative impacts of all planned dams. There are plans for 151 new dams greater than 2 MW over the next 20 years, more than a 300% increase. These dams would include five of the six major Andean tributaries of the Amazon. Our ecological impact analysis classified 47% of the potential new dams as high impact and just 19% as low impact. Sixty percent of the dams would cause the first major break in connectivity between protected Andean headwaters and the lowland Amazon. More than 80% would drive deforestation due to new roads, transmission lines, or inundation. We conclude with a discussion of three major policy implications of these findings. 1) There is a critical need for further strategic regional and basin scale evaluation of dams. 2) There is an urgent need for a strategic plan to maintain Andes-Amazon connectivity. 3) Reconsideration of hydropower as a low-impact energy source in the Neotropics.
Pandit, M.K. and Grumbine, R.E. (2012), Potential Effects of Ongoing and Proposed Hydropower Development on Terrestrial Biological Diversity in the Indian Himalaya. Conservation Biology, 26: 1061-1071. https://doi.org/10.1111/j.1523-1739.2012.01918.x
Indian Himalayan basins are earmarked for widespread dam building, but aggregate effects of these dams on terrestrial ecosystems are unknown. We mapped distribution of 292 dams (under construction and proposed) and projected effects of these dams on terrestrial ecosystems under different scenarios of land-cover loss. We analyzed land-cover data of the Himalayan valleys, where dams are located. We estimated dam density on fifth- through seventh-order rivers and compared these estimates with current global figures. We used a species–area relation model (SAR) to predict short- and long-term species extinctions driven by deforestation. We used scatter plots and correlation studies to analyze distribution patterns of species and dams and to reveal potential overlap between species-rich areas and dam sites. We investigated effects of disturbance on community structure of undisturbed forests. Nearly 90% of Indian Himalayan valleys would be affected by dam building and 27% of these dams would affect dense forests.
Our model projected that 54,117 ha of forests would be submerged and 114,361 ha would be damaged by dam-related activities. A dam density of 0.3247/1000 km2 would be nearly 62 times greater than current average global figures; the average of 1 dam for every 32 km of river channel would be 1.5 times higher than figures reported for U.S. rivers. Our results show that most dams would be located in species-rich areas of the Himalaya. The SAR model projected that by 2025, deforestation due to dam building would likely result in extinction of 22 angiosperm and 7 vertebrate taxa. Disturbance due to dam building would likely reduce tree species richness by 35%, tree density by 42%, and tree basal cover by 30% in dense forests. These results, combined with relatively weak national environmental impact assessment and implementation, point toward significant loss of species if all proposed dams in the Indian Himalaya are constructed.
Aris, M,. Cochrane, T., Lawrence, K., Killeen T., & Farrell, T. (2011). Paying the forest for electricity: A modelling framework to market forest conservation as payment for ecosystem services benefiting hydropower generation. Environmental Conservation, 38(4), 473-484. doi:10.1017/S0376892911000464
The operation and longevity of hydropower dams are often negatively impacted by sedimentation. Forest conservation can reduce soil erosion, and therefore efforts to maintain upstream forest cover within a watershed contribute to the economic life span of a hydropower facility. The cost of forest conservation can be viewed as an investment in hydropower and be financed via a payment for ecosystem services (PES) scheme. A novel modelling framework is used to estimate payments for forest conservation consisting of: (1) land-use change projection; (2) watershed erosion modelling; (3) reservoir sedimentation estimation; (4) power generation loss calculation; and (5) PES scheme design. The framework was applied to a proposed dam in Cambodia (Pursat 1). The estimated net present value of forest conservation was US$ 4.7 million when using average annual climate values over 100 years, or US$ 6.4 million when considering droughts every eight years. This can be remunerated with annual payments of US$ 4.26 ha−1 or US$ 5.78 ha−1, respectively, covering forest protection costs estimated at US$ 0.9 ha−1 yr−1. The application of this type of PES represents a rational option that allows for conservation and development of hydropower watersheds susceptible to erosion and sedimentation.
Ulyshen, M. and Horn, S. (2009) An appeal to Protect and Restore Exposed Riverine Sediments (ERS) in North America. In: Stream Restoration: Halting Disturbances. Eds. Gillian D. Hayes and Timothy S. Flores, 2009 Nova Science Publishers.
Few streams in North America remain unaltered. In the United States, for example, a country with over 80,000 dams and extensively degraded riparian forests, only 2% of rivers are considered “unimpacted” (Palmer et al. 2007 and sources therein). While extensive surveys are needed before conservations plans can be developed for North American ERS arthropods, steps should be taken in the meantime, when possible, to protect and restore ERS habitats. ERS are less complex than many imperiled ecosystems and should be less difficult to restore. However, while arthropods are disturbance-adapted and frequently exhibit high recolonization potential, some species are less resilient [Hering et al. 2004] and the lack of previous survey data will make it difficult to monitor arthropod community recovery. Consequently, protecting ERS habitats from further degradation should be a top priority.
Intergovernmental Panel on Climate Change [IPCC]. Fourth Assessment Report. 2007. Available online: https://www.ipcc.ch/site/assets/uploads/2018/02/ar4_syr_full_report.pdf .
John A. Downing, Yves T. Prairie, Jonathan J. Cole, Carlos M. Duarte, Lars Tranvik, Robert Striegl, William H. McDowell, Pirkko Kortelainen, Nina Caraco, John M. Melack and Jack Middelburg. 2006. The global abundance and size distribution of lakes, ponds, and impoundments. Limnology and Oceanography. 51(5): 2388-2397.
One of the major impediments to the integration of lentic ecosystems into global environmental analyses has been fragmentary data on the extent and size distribution of lakes, ponds, and impoundments. We use new data sources, enhanced spatial resolution, and new analytical approaches to provide new estimates of the global abundance of surface-water bodies. A global model based on the Pareto distribution shows that the global extent of natural lakes is twice as large as previously known (304 million lakes; 4.2 million km2 in area) and is dominated in area by millions of water bodies smaller than 1 km2. Similar analyses of impoundments based on inventories of large, engineered dams show that impounded waters cover approximately 0.26 million km2. However, construction of low-tech farm impoundments is estimated to be between 0.1% and 6% of farm area worldwide, dependent upon precipitation, and represents ≫77,000 km2 globally, at present. Overall, about 4.6 million km2 of the earth’s continental “land” surface (≫3%) is covered by water. These analyses underscore the importance of explicitly considering lakes, ponds, and impoundments, especially small ones, in global analyses of rates and processes.
Laurance,W., Albernaz, A., Fearnside, P., Vasconcelos, H., and Ferreira, L.,(2004). Deforestation in Amazonia. Letter to the Editor in Science, Vol. 304.
Dudgeon, D. (2000). The Ecology of Tropical Asian Rivers and Streams in Relation to Biodiversity Conservation, Annual Review of Ecology and Systematics 2000 31:1, 239-263 https://doi.org/10.1146/annurev.ecolsys.31.1.239
Tropical Asian rivers support a rich but incompletely known biota, including a host of fishes, a diverse array of benthic invertebrates, and an assemblage of mammals adapted to riverine wetlands. River ecology is dominated by flow seasonality imposed by monsoonal rains with profound consequences for fishes and zoobenthos. Information on life histories, feeding, and the trophic base of production of these animals is summarized. Widespread use of allochthonous foods by fishes and zoobenthos is apparent. Migration by fishes is often associated with breeding and results in seasonal occupation of different habitats. Riverine biodiversity is threatened by habitat degradation (pollution, deforestation of drainage basins), dams and flow regulation, as well as over-harvesting. Conservation efforts in tropical Asia are constrained by a variety of factors, including lack of ecological information, but the extent of public awareness and political commitment to environmental protection are likely determinants of the future of riverine biodiversity.
Rodriguez MC. Deforestation Imperils Ambuklao. Popul Forum. 1990;(1):7-8. PMID: 12343166. https://pubmed.ncbi.nlm.nih.gov/12343166/
Due to a massive accumulation of sedimentation, the Ambuklao Dam may have to cease operation, a problem that is the result of the rampant destruction of the surrounding environment. The Ambuklao Dam is located in the Benguet region of the Philippines. Completed in 1956, Ambuklao is the biggest earth-and-rockfill dam in the Far East, build to provide electricity and serve as an irrigation source for the region. The dam was supposed to service the region until 2006, but it may now suspend operation in 1995. When the dam was built, the designers anticipated that 2.6 million cu. m. silt would accumulate each year for the 1st 10 years, but recently, the accumulation rate has hovered around 3.6 million cu. m. Already an estimated 110 million cubic meters of silt has piled up in the water reservoir. Experts blame the problem on massive erosion, the result of the deforestation of the surrounding environment caused by the practices of people: slash-and-burn farming, grazing, logging, mining, quarrying, road-building, and forest fires started by humans. Despite a ban on the cutting of the Benguet pine, a valuable timber for construction, logging has continued. And although mining companies are required to set up impounding ponds and siltation dams, few of them actually comply. These problems have been compounded by the growing numbers of migrants to the region, who come because of the region’s work opportunities. Between 1980 and 2000, the population of the watershed region is expected to increase from 134,496 to 231,307 — a 71.9% increase. Unless the destructive practices are curbed, the Ambuklao dam will soon cease to operate.