Impacts of boreal hydroelectric reservoirs on seasonal climate and precipitation recycling as simulated by the CRCM5: a case study of the La Grande River watershed, Canada

Abstract

Located in northern Quebec, Canada, eight hydroelectric reservoirs of a 9782-km 2 maximal area cover 6.4% of the La Grande watershed. This study investigates the changes brought by the impoundment of these reservoirs on seasonal climate and precipitation recycling. Two 30-year climate simulations, corresponding to pre-and post-impoundment conditions, were used. They were generated with the fifthgeneration Canadian Regional Climate Model (CRCM5), fully coupled to a 1D lake model (FLake). Seasonal temperatures and annual energy budget were generally well reproduced by the model, except in spring when a cold bias, probably related to the overestimation of snow cover, was seen. The difference in 2-m temperature shows that reservoirs induce localized warming in winter (+0.7 ± 0.02°C) and cooling in the summer (−0.3 ± 0.02°C). The available energy at the surface increases throughout the year, mostly due to a decrease in surface albedo. Fall latent and sensible heat fluxes are enhanced due to additional energy storage and availability in summer and spring. The changes in precipitation and runoff are within the model internal variability. At the watershed scale, reservoirs induce an additional evaporation of only 5.9 mm year −1 (2%). We use Brubaker's precipitation recycling model to estimate how much of the precipitation is recycled within the watershed. In both simulations, the maximal precipitation recycling occurs in July (less than 6%), indicating weak land-atmosphere coupling. Reservoirs do not seem to affect this coupling, as precipitation recycling only decreased by 0.6% in July.

Quantifying Water Impoundment-Driven Air Temperature Changes in the Dammed Jinsha River, Southwest China

“…Miller et al [21] modeled the climate changes for eight weeks in the Three Gorges Dam area and suggested that the decreased local surface and air temperature likely occurred because the reservoir acted as a potential evaporating surface. Irambona et al [22] found that reservoirs induced localized 2 m temperature warming in winter and cooling in the summer in the La Grande River watershed. Wang et al [18] revealed that the reservoir had both warming and cooling effects on the surface temperature in different parts of the dry-hot valley.…”

Modeling reservoir surface temperatures for regional and global climate models: a multi-model study on the inflow and level variation effects

“…Numerical weather prediction (NWP) and climate modeling are essential tools in research and applied science applications (e.g., Bauer et al, 2015;Forster, 2017;Jacob et al, 2020). Motivated by the need to increase the reliability of climate and weather projections, the core numerical models undergo continuous improvements aiming at the best compromise between model representativity and computational efficiency (Flato et al, 2013).…”

Evaporation from boreal reservoirs: A comparison between eddy covariance observations and estimates relying on limited data

“…The stored energy acts as a source to fuel evaporation during fall and at night throughout the ice‐free season (Boudreau & Rouse, 1995; Nordbo et al, 2011). These features produce distinctive diurnal and annual patterns of evaporation (Granger & Hedstrom, 2011; Heikinheimo et al, 1999; Irambona et al, 2018; Nordbo et al, 2011; Strachan et al, 2016; Venalainen et al, 1999).…”