Hydrological and water temperature modelling for dam decommissioning and climate change studies

The Mactaquac Dam and Generating Station, a 672 MW run-of-the-river hydroelectric facility located on the Saint John River, Canada, will have to be decommissioned or reconstructed by 2030. In order to simulate the impact of reservoir emptying (drawdown) and climate change on the thermal regime of the lower reaches of the river, the CEQUEAU hydrological and water temperature model was used. The model was successfully calibrated and validated for both flow and water temperature, with Nash coefficients ranging from 0.63 to 0.86 for flow and RMSE ranging between 0.74 °C and 1.3 °C for temperature. Subsequently, different drawdown and climate change scenarios were simulated using the calibrated models. Median value of maximum water temperature in the river is expected to increase by 2-3 °C by 2100, regardless of the dam reconstruction scenario.

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