We hereby present a study on heat and mass transfer between free surface water and the atmosphere in Burkina Faso. We preferentially chose the city of Ouagadougou to conduct this study. One of the major problems in studying evaporation is how to determine water surface temperature and the flow of water evaporated. We calculated this surface temperature using the dichotomy method (Saighi, 2002) applied to the energy balance formula. The calculation of this temperature enabled us to draw the evolution of the evaporation according to the time and surface temperature for a period of ten years considered in the study. The results obtained are satisfactory because we now have the minimum (23.64 °C) and maximum (36.64 °C) values of surface temperatures. Concerning the evaporated water flows, we got extreme values like 6.25 mm for the minimum value and 12.7 mm for the maximum one for the ten years considered. We compared the values of the water flow calculated using the energy balance formula with that measured by the Burkina Faso Meteorology Department using an "A" class BAC. We were able to calculate an average error between both values of 12.7%; an error that we consider acceptable.

Evaporation, Thermal transfer, energy balance