The cascading approach assumes the water can enter the layer below only when the current layer reaches field capacity.

The outflow flux for a generic layer i (Wout(i)) is:

And the new SWC(i) is

where Wout(i) is the outflow flux of soil layer i (mm d-1), Win(i) is the water entering the current soil layer (mm d-1); equal to net rainfall if the current layer is the first one. LTHi is the current soil layer thickness (m), FC(i) is the volumetric field capacity (m3 m-3), SWC(i) is the initial volumetric soil water content (m3 m-3), Evap(i) (mm d-1) is the actual soil evaporation that typically occurs in the first 10 cm of soil, Transp(i) (mm d-1) is the water uptake by roots and i is current soil layer number.

Note that all the values of field capacity and wilting point are referred to soil particles <=2 mm, and skeleton act subtracting soil volume. Field capacity and Wilting point values are automatically corrected for skeleton.

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