In 1993, a vast study began on the production and emission of CO2 from hydroelectric reservoirs in central northern Qu¿bec. During the sampling field trips, information was collected about water temperature profiles, CO2 surface atmospheric concentrations, dissolved CO2 concentration profiles through the depth of the reservoirs, and CO2 fluxes at the surface and the bottom of the reservoirs, as well as many surface meteorological parameters. One of the goals of the project was to develop a mathematical model capable of simulating the physical processes responsible for the vertical transport of dissolved CO2 in hydroelectric reservoirs. This combined approach of measurements and numerical modeling confirmed certain hypotheses concerning the missing source of CO2, the existence of a spring peak of CO2 emission and an intense fall peak of CO2 emission for deep reservoirs. Moreover, a relation between differences in patterns of CO2 emission and reservoir depth was highlighted. It is shown that the numerical model developed in this research can be used to develop sampling strategies based on the characteristics of temporal and spatial distributions associated with each reservoir.