Climate Change Impacts on Water Resources of the Largest Hydropower Plant Reservoir in Southeast Brazil

Abstract

Approximately 70% of all the electric energy produced in Brazil comes from hydropower plants. In this context, the Grande River Basin (GRB) stands out in Brazil. Some studies have been carried out to investigate the impacts of climate change in tropical regions to support water resources’ management and planning. This study aims to project the changes in the runoff that feed the Furnas Hydropower Plant (FHP) reservoir (GRB-Furnas basin), the largest and most important facility in Southeast Brazil. The lavras simulation of hydrology model (LASH) was used to project the impacts on runoff and hydrological droughts over the century in GRB-Furnas. The regional climate models (RCMs) Eta-HadGEM-ES, Eta-MIROC5, and Eta-CanESM2 forced the LASH model from 2007 to 2099, taking the representative concentration pathways (RCPs) 4.5 and 8.5. LASH simulated the runoff adequately for the baseline period (1961–2005) using the RCMs’ outputs. A noticeable reduction in precipitation was identified in the wet season, especially in the 2007–2040 period for RCP4.5 and in the 2071–2099 period for RCP8.5. As a result, a significant reduction in the runoff, mainly in the baseflow, and an increase in droughts’ severity were projected throughout the XXI Century, which may compromise the water security to the FHP reservoir.

Quantifying the climate change‐driven impacts on the hydrology of a data‐scarce watershed located in the Brazilian Tropical Savanna

“…These severe impacts projected by RCP 8.5 were expected because it represents the highest radiative forcing. In addition, RCP 8.5 presents greater uncertainties, as found by Mello et al (2021) in a study performed in southeast Brazil. The 2041–2070 time slice showed a less accentuated reduction than the other periods in all scenarios, except in Eta/MIROC5 RCP 4.5, which projected the lowest decrease in the first time slice.…”

“…Despite the suitable representation of the maximum streamflows, SWAT underestimated the highest flows (Figure 3). The model's capability in simulating the maximum streamflows can be verified through the average daily streamflow with a frequency lower than 5% (MaSi) (Mello et al, 2021). The observed and simulated MaSi obtained for SM‐TARB were 2465 — and 2222 m 3 .s −1 , respectively, which means an underestimation of 9.8% of the highest streamflows.…”

“…The representative concentration pathways (RCPs) adopted in this study were RCP 4.5 and RCP 8.5, which are considered the anthropogenic and non-anthropogenic radiative forcings (4. other studies using these RCM datasets (Oliveira, Leite, et al, 2017;Oliveira, Mello, et al, 2017, 2019Rodrigues et al, 2020;Mello et al, 2021).…”

Climate change impact assessment in a tropical headwater basin

“…This is also observed in regional scale projections by RCMs worldwide, due to model uncertainty while simulating plants' water-use response to changes of CO2 concentration (Lehner et al, 2019). Thus, changes in simulated discharge and total runoff reflect these uncertainties of precipitation simulations by RCMs (Mello et al, 2021).…”

Accuracy vs Realism: Does including reservoirs improve hydrological models?

“…In this study, we focus on including human influence, by means of reservoirs, in hydrological modeling across catchments in Brazil. Brazil has a dense network of reservoirs (Cavalcante et al, 2020;Souza Filho, 2009) with a high socio-economic relevance; almost 70% of the country's electricity production comes from hydropower plants (Mello et al, 2021). Furthermore, the Brazilian reservoirs are used to ensure the water supply of agricultural production (Multsch et al, 2020) and flood control (Fleischmann et al, 2019), in addition to being the main source of water for human consumption in the semiarid region (Braga et al, 2012;Mamede et al, 2018).…”