The liquid water released from snow pack flows into depression storage first. It will first fill the available storage and then flow out. The storage is then restored through evaporation and infiltration (in pervious area).

= the amount of water flow out of depression storage (mm),
= the initial amount of water stored in depression storage (mm),
= the amount of water lost through evaporation (mm),
INFIL = the amount of water infiltrates to active soil zone (mm),
= the storage capacity (mm).

Then the water held in the storage is updated.

The evaporation is calculated with upper limit set to PET. The infiltration INFIL is only considered in pervious area and it’s calculated with given infiltration ratio as: