SZ exchange with ponded water

The saturated zone component calculates the recharge/discharge between ponded water (OL) and the saturated zone (SZ) without the unsaturated zone, if the unsaturated zone is not included or if the phreatic surface is above the topography.

The exchange between SZ and OL is calculated implicitly using the Darcy equation

where C_1/2 is the conductance between the topography and the middle of the upper SZ calculation layer.

In the case of full contact between OL and SZ the conductance is calculated by

(30.20)   

where Dz is the thickness of layer 1 and K_z, is the vertical conductivity of layer 1.

In areas with reduced contact between overland and the saturated zone, the conductance between OL and layer 1 is calculated by

(30.21)   

where Dz is the thickness of layer 1 and K_z, is the vertical conductivity of layer 1 and K_leak is the specified leakage coefficient.