The volume of precipitation falling on the reservoir during a given day is calculated:
Vpcp​=10∗Rday​∗SA 8:1.1.5
where Vpcp​ is the volume of water added to the water body by precipitation during the day (m3 H2​O), Rday​ is the amount of precipitation falling on a given day (mm H2​O), and SA is the surface area of the water body (ha).