:Infiltration function is greater than saturated

Recharge

Recharge from the soil column to the underlying groundwater system is a function of soil moisture content and depth to watertable. A minimal parameterisation must account for the changes in the unsaturated zone storage (and therefore soil moisture) and depth to watertable allowing for the fact that any functional relationships may be highly nonlinear. Two fundamental approaches have been adopted in the current model namely;

1. matrix/crack flow formulation
2. Darcian flux formulation

Each of these formulations are described below.

a) Matrix/crack recharge formulation

The model caters for both matrix dominated and crack flow dominated accession to groundwater. The depth to groundwater is normalised as defined by equation(3) such that as the depth to groundwater increases the normalised depth decays to zero. Infiltration is partitioned to groundwater according to:

where q_rech is the recharge flux, dwt is the depth to watertable, dwt_shallow  is the assigned depth to shallow watertable, dwt_deep is the assumed