Setting of Initial and Boundary Conditions for Water Flow



Initial Condition
Uniform water content Set higher value than 0.
Uniform pressure head Set negative value (not suction).
Static profile (equilibrium) This is profile when initial flux is zero. Please specify pressure head at the top.
Prescribed water content profile Maximum number of acceptable data is 20 and values of element between measured values are calculated with linear interpolation. First column is depth in cm and second is volumetric water content (0-1). Arrange from the top.
Common format of data files

Initial hysteretic process :
Although this software handles hysteresis using a simple method by Kool and Parker (1987), it is assumed that any depth is on main drying or wetting curves. Please select which is more prevalent.

Upper Boundary Condition
Upper boundary condition for liquid water flow is configured here.
Constant condition (including zero) Select this one if you want to analyze experiment at constant flux (including zero).
Constant Pressure(ponding) Select this one if the soil surface is ponded at constant depth. If you select "Variable condition (using a file)" in the atmospheric boundary condition dialogbox, this choise is neglected.
Variable flux Select this one for simulating irrigation. Rainfall should be input in the meteolorological condition file.
In the data file, first column is time and second one is flux (cm/time). Use same unit of time as set in the general information dialogbox.
If the irrigation is applied stepwise, write same time for two rows, and write flux before and after change, respectively.[example]
Although values between the input data are calcutated with linear interpolation, extrapolation is not perfomed. Make sure that fluxes at 0 and (time after) final time are inclu


Lower Boundary Condition
Constant pressure head Select here if ground water table is shallow and nearly constant or to simulate experiment with constant pressure head at the lower boundary.
Gravitational flow only If this is selected, drainage occurs by gravity only. It may be appropriate if ground water table is deep.
Impearmeable This is usually selected to simulate experiment with closed bottom. This is automatically selected for inverse parameter estimation with evaporation methods.
Variable pressure head Select here if pressure head at the lower boundary is monitored using tensiometer or to simulate experiment with variable pressure head at the lower boundary.
File of pressure at the bottom

Hydraulic conductance of the filter
Input hydraulic conductance (kf ) of the membrane or porous plate. If it is field, input very large value.
Definition of hydraulic conductance:
ql = kf (yu- yd)
where ql: liquid water flux (cm/time) with positive downward, hu: pressure head (cm) at the upper side of the filter, hd pressure head (cm) at the upper side of the filter.

[Numerical Detail]
By clicking this, you can change detailed settings for numerical analysis. If you face crash during calculation, manipulating those values may solve the trouble.