Karina Lalchand Sheri (National Institute of Education (Singapore))

Keywords
Geography
Junior College
Secondary School

This paper investigates the impact of both Santo Antônio and Jirau mega dams on the downstream geomorphology of, more specifically, island and bar dynamics along the Madeira River in the Amazon. Water level data from gauge stations and remote sensing images from 1990 to 2019 were deployed to make sense of the changes in the number, area and volume of islands/bars downstream of the dams. The data indicated that both Santo Antônio and Jirau, which are run-of-river dams have not had significant impacts on the area and volume of islands/bars found in Madeira River’s five reaches. A reduction in the volume of islands/bars was marginally more substantial than a negligible reduction in their areal extent. Trapped sediments behind both dams could have accounted for the slight decrease in island/bar volume. Overall, this paper opens up a discussion on the sustainability of fluvial/geomorphological features and water regimes, alongside the installation of run-of-river dams as an allegedly more sustainable alternative to other kinds of hydraulic structures and non-renewable sources of energy. Student-teachers who are taking tertiary courses in physical Geography, as well as A Level Geography educators are likely to take interest in this in-depth and well contextualised case study of mega dams in Brazil.

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