Contrasting regional discharge evolutions in the Amazon basin (1974–2004)

Espinoza, Jhan Carlo; Guyot, Jean‐Loup; Ronchail, Josyane; Cochonneau, Gérard; Filizola, Naziano; Fraizy, Pascal; Labat, David; Oliveira, Eurides de; Ordoñez, Juan Julio; Vauchel, Philippe

doi:10.1016/j.jhydrol.2009.03.004

Cited by 170 publications

(99 citation statements)

References 45 publications

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“…Another factor specifically related to dams is that sedimentation [10] will reduce the storage capacity of the reservoir, and diminish the capacity of the power plants to generate electricity. Finally, global climate change is predicted to diminish the average flow of the rivers in the southeast of the Amazon region (the location of most of the proposed dams) and will increase the variability of the flows [11]. Both the sedimentation and the change in the flows of the rivers will reduce the capacity of the dams to generate electrical power.…”

Section: The Economics Of Irreversible Investmentsmentioning

confidence: 99%

False Shades of Green: The Case of Brazilian Amazonian Hydropower

2014

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Abstract: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. OPEN ACCESSEnergies 2014, 7 6064

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Section: The Economics Of Irreversible Investmentsmentioning

confidence: 99%

False Shades of Green: The Case of Brazilian Amazonian Hydropower

2014

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“…The 17121000 -Caiabis (Balsa -Itapaiuna) Station has such high trends because its time series is very short, and has some gaps. The 17730000 -Itaituba station data results are different from other studies (Espinoza Villar et al, 2009) because different rating curves were used to calculate the flow from the river stage. This study's results in that station suffer from inconsistencies in the data, especially for minimum flows.…”

Section: Resultsmentioning

confidence: 68%

“…In El Niño (La Niña) years, the discharges diminish (increase), especially in the basin central regions. Some studies (Espinoza Villar et al, 2009) report interdecadal oscillations of 15.5 years in the minimum discharges, 17 years in the average discharges and bidecadal oscillations in the maximum discharges. The oscillation in the average discharge is connected to the South American Monsoon System cycle.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of monotonic trends for streamflow in austral Amazon, Brazil: a case study for the Xingu and Tapajós rivers

Moura¹

2015

Proc. IAHS

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Abstract. This paper has the goal of evaluating monotonic trends in the Xingu and Tapajós river basins in the Austral Amazon region, Brazil. Non-parametric statistical tests such as Mann-Kendall, Bootstrap MannKendall, Sen and Bootstrap Sen are applied on streamflow gauging stations data, to determine the significance and magnitude of possible trends. Data in these river basins is relatively scarce, with time series ranging from twenty to forty years, having many gaps. Former studies indicate a decreasing trend for both annual average and minimum streamflow values in the Tapajós river basin, with 99 % confidence level, and a decrease in maximum values in the Xingu river basin, with 90 % confidence level. However, past analyses have only used one station near the basin outlet. This study uses data from 7 gauging stations in the Xingu basin and 14 stations in the Tapajós basin. Results indicate opposite trends at the 95 % confidence level for different regions in the basins, and for different flow regimes. For the Xingu river basin, trends in the minimum flow for different sub-basins even out at the Altamira station, near its outlet. For the Tapajós river, the southeastern part of the basin has increasing trends, while the southwestern part decreases. At the Itaituba station, they also balance out.

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“…These are likely caused by the rivers' high sedimentary load combined with a perched channel during the dry season and an extremely low along-valley slope, which not only bring the rivers to the threshold conditions for the formation of crevasse splays, but also trigger the crevasses. In this setting, the decrease in average precipitation over the SAFB experienced in recent years (Espinoza Villar et al, 2009) and the lengthening of the dry season (Fu et al, 2013) increase the frequency of river crevasses and move their formation closer to the Andes. The fact that all the modern crevasses are closer to the Andes than the mid-to late Holocene distributary systems formed by the rivers in groups 2 and 3 suggests, on a millennial scale, a common climatic (Mayle et al, 2000;Baker, 1977) and/or neo-tectonic (Lombardo, 2014;Dunne et al, 1998) control over the shifting of these rivers' depozone.…”

Section: Discussionmentioning

confidence: 99%

Alluvial plain dynamics in the southern Amazonian foreland basin

Lombardo¹

2016

Earth Syst. Dynam.

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Abstract. Alluvial plains are formed with sediments that rivers deposit on the adjacent flood-basin, mainly through crevasse splays and avulsions. These result from a combination of processes, some of which push the river towards the crevasse threshold, while others act as triggers. Based on the floodplain sedimentation patterns of large rivers in the southern Amazonian foreland basin, it has been suggested that alluvial plain sediment accumulation is primarily the result of river crevasse splays and sheet sands triggered by above-normal precipitation events due to La Niña. However, more than 90 % of the Amazonian river network is made of small rivers and it is unknown whether small river floodplain sedimentation is influenced by the ENSO cycle as well. Using Landsat images from 1984 to 2014, here I analyse the behaviour of all 12 tributaries of the Río Mamoré with a catchment in the Andes. I show that these are very active rivers and that the frequency of crevasses is not linked to ENSO activity. The data suggest that most of the sediments eroded from the Andes by the tributaries of the Mamoré are deposited in the alluvial plains, before reaching the parent river. The mid-to-late Holocene paleo-channels of these rivers are located tens of kilometres further away from the Andes than the modern crevasses. I conclude that the frequency of crevasses is controlled by intrabasinal processes that act on a yearly to decadal timescale, while the average location of the crevasses is controlled by climatic or neo-tectonic events that act on a millennial scale. Finally, I discuss the implications of river dynamics on rural livelihoods and biodiversity in the Llanos de Moxos, a seasonally flooded savannah covering most of the southern Amazonian foreland basin and the world's largest RAMSAR site.

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Contrasting regional discharge evolutions in the Amazon basin (1974–2004)

Cited by 170 publications

References 45 publications

False Shades of Green: The Case of Brazilian Amazonian Hydropower

False Shades of Green: The Case of Brazilian Amazonian Hydropower

Evaluation of monotonic trends for streamflow in austral Amazon, Brazil: a case study for the Xingu and Tapajós rivers

Alluvial plain dynamics in the southern Amazonian foreland basin

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