Downstream alterations on hydrodynamic fields by hydropower plant operations: implications for upstream fish migration
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PERSPECTIVES ON SUSTAINABLE HYDRO-POWER
Downstream alterations on hydrodynamic fields by hydropower plant operations: implications for upstream fish migration Ludmila Moura Moreira Mendes Hersilia Andrade Santos
. Guilherme Antoˆnio Ribeiro Souza
.
Received: 1 March 2020 / Revised: 8 September 2020 / Accepted: 14 September 2020 Ó Springer Nature Switzerland AG 2020
Abstract This study identifies hydrodynamic alterations in flow downstream of a dam that are related to hydropower plant (HPP) operation and that might attract Neotropical potamodromous fish to unsafe places in the tailrace during their reproductive migration. Our hypotheses are (1) the hydrodynamic flow in the tailrace presents conditions that are strong attractive for fish than those found in the downstream reach and (2) there are no velocity barriers preventing the upstream migrant from reaching the tailrace over a wide range of turbine discharge. Two calibrated numerical models were created for the Treˆs Marias HPP (Brazil), using different turbine discharges: (1) a three-dimensional (3D) model of flow in the tailrace
Guest editors: Ingeborg P. Helland, Michael Power, Eduardo G. Martins & Knut Alfredsen / Perspectives on the environmental implications of sustainable hydro-power L. M. M. Mendes (&) G. A. R. Souza Programa de Po´s-Graduac¸a˜o em Engenharia Civil, Centro Federal de Educac¸a˜o Tecnolo´gica de Minas Gerais, Av. Amazonas 7675, Belo Horizonte, Minas Gerais 30510-000, Brazil e-mail: [email protected] G. A. R. Souza e-mail: [email protected] H. A. Santos Departamento de Engenharia Civil, Centro Federal de Educac¸a˜o Tecnolo´gica de Minas Gerais, Av. Amazonas 7675, Belo Horizonte, Minas Gerais 30510-000, Brazil e-mail: [email protected]
and (2) a two-dimensional (2D) model for flow in the 3-km reach downstream of the dam. Resulting flow fields of the Treˆs Marias HPP tailrace have elevated hydraulic strain and velocity homogeneity by as compared to the flow field of the downstream reach. The tailrace velocities are slow for mature individuals of all study species, which may swim from downstream reach to unsafe areas in their sustainable and prolonged mode by available corridors for different turbined discharges. Keywords Dam Tailrace attraction Swimming performance Fish conservation Environmental impact
Introduction Hydropower generation is often presented as a solution for today’s increasing world electricity demands, especially in countries in Asia, Africa, and Latin America (Hamududu & Killingtveit, 2012; de Faria et al., 2017). The International Energy Agency estimates that hydropower capacity will increase worldwide by 9% until 2024, led by China, India, and Brazil (IEA, 2019). As a consequence, large dams are related to several environmental (Von Sperling, 2012), social (Tilt et al., 2009), and economic impacts (Ansar et al., 2014). Large damming is now considered
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Hydrobiologia
an anthropogenic stress on the world’s big rivers (Best, 2019). More than 450
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