Boundary and initial conditions
As is illustrated in Fig. 1, the top of the model is the ground surface,
so the upper boundary of the model is set with constant pressure (1.0
bar). The lateral boundaries are regarded as non-flow since they are
vertical and hence parallel to the flow direction of the infiltrated
water in vadose zone, which is well known to be predominately vertical.
The initial water table is located at the depth of 2 m in our
simulations, since the actual water tables in the test site were
observed to be mostly in the range of 1.6~2.3 m below
the surface (Wang, 2013). The lower boundary is defined as a non-flow
boundary, allowing for elevation in the phreatic surface in case
percolation occurs from the unsaturated zone.
To simulate a fairly dry condition, the initialSW is set to be 0.2 for all the model grid cells
for C0. The temperature is simply taken to be 23 °C throughout the model
domain and isothermal processes are modeled for all the cases. The
initial pore pressure is set as 0.91 bar.