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Climate change enhances deepwater warming of subtropical reservoirs: evidence from hydrodynamic modelling

2021; Springer Science+Business Media; Volume: 166; Issue: 1-2 Linguagem: Inglês

10.1007/s10584-021-03124-x

1573-1480

Laura Melo Vieira Soares, Maria do Carmo Calijuri, Talita Silva, Evlyn Márcia Leão de Moraes Novo,

Aquatic Ecosystems and Phytoplankton Dynamics

Lake surface warming and thermal responses to climate change have been widely reported, especially in temperate regions. Evidence of reservoir response in low latitudes is still limited. In this study, the vertical profile of water temperature in the Barra Bonita Reservoir (Brazil) is simulated using the one-dimensional General Lake Model (GLM), calibrated, and validated using in-situ data. Water temperature and reservoir hydrodynamics are simulated over 26 years (1993–2018) to investigate warming trends, seasonal patterns, Schmidt stability, and the number of stratified days per year. Results indicate that the reservoir has experienced significant warming since 1993 related to increasing air temperature and decreasing wind speed. Water temperature increases (p value <0.001) from the surface (+ 1.02 °C per decade) to the bottom (0.33 °C per decade). Higher warming rates are detected during the dry and cold season. Significant increasing trends are found for Schmidt stability and in the number of stratified days per year. Deepwater warming is directly related to increasing air temperature and frequent mixing episodes which transfer heat from surface to bottom waters. A deep outlet structure and an artificially controlled water level may enhance deepwater warming during the dry season. Our findings contribute to the understanding of subtropical reservoirs’ response to climate change and help to guide planning strategies for ensuring the security of water storage and ecosystem services they provide.