Geology Question:

Answer #1
Factors such as the volume and surface area of the lake together with average wind speed and temperature at the surface are the factors that can be used to work out how much evaporation there is at the surface.

Answer #2
By using box models where evaporation, infiltration, floating are counted separately and moving water from one to another system is calculated with counting measured precipitations and measumerement of water floating on the surface and in the underground.