1-D Lake Model Assessment for Estimating Evaporation from a Hydropower Reservoir
Abstract
Freshwater reservoirs have the capacity to modify the regional climate through mass, energy, and momentum exchanges with the atmosphere. They may also alter the water budget of their watershed. For example, some studies argued that hydropower reservoirs have the disadvantage of increasing water losses through evaporation, compared to the situation for the same location prior to impoundment, reducing water availability for other uses. Knowing that evaporation is a key component of the water balance and that very few studies have focused on evaporation from northern reservoirs, which are covered by ice for part of the year, there is a real need for models that can provide reliable estimates of lake hydrometeorological fluxes. This project focuses on the modeling of the evaporation from the surface of a hydroelectric reservoir located in the boreal biome of eastern Canada. More specifically, observations are available for the 85-km2 La Romaine 2 hydroelectric reservoir (50.7°N, 63.2°W), where two flux towers (one on the shore and one on a raft) and a vertical chain of thermistors, were deployed. The analysis focuses on direct flux measurements collected with eddy covariance systems. Exchanges between the water surface and the atmosphere are simulated by the Canadian Small Lake Model (CSLM), a 1-D physical-based surface scheme designed to be coupled with a numerical weather prediction model. The model also simulates the thermal regime of the water body, including ice formation. A good agreement between observed and modeled latent and sensible heat fluxes is found during the whole period, except for ice melt conditions where latent heat fluxes are higher than observations. The reservoir thermal regime is in general well captured by the model. The model shows a good performance for freeze-up and melt dates with a few days lag for the three years of simulation. However, water temperatures are underestimated in the summer period. The model distributes the available energy over the entire water column, resulting in an underestimation of the surface temperature and an overestimation of the mixed layer depth. Comparison of field measurements and simulations confirms the CSLM ability to reproduce the turbulent fluxes and the temperature behavior of the reservoir.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H55T0967K