SaltMod

A mathematical, numerical simulation model
describing the relations between agriculture, crop
rotation, irrigation, rainfall, potential and
actual evaporation (evapotranspiration), climate,
hydrology, depth and level of watertable,
capillary rise, deep percolation, soil salinity
and subsurface drainage by drains or wells, and
reuse (conjunctive use) of ground and drain water
from wells. It includes farmers' responses to
water logging and soil salinity.

SahysMod

A combination of Saltmod with a model of ground
water flow and hydraulics to account for large
spatial variation through a network of polygons.
It includes phreatic (unconfined) aquifers as well
as soil layers with slow vertical hydraulic
conductivity (soil permeability for water) resulting
in semiconfined (leaky) aquifers.

SaltCalc

A simplified version of SaltMod with the
advantage that calculations are made for shorter
time steps (monthly instead of seasonally).
SaltCalc can be used when field observations of
irrigation, water table and soil salinity have
been made and one wishes to develop a model for
that situation. Normally, calibration of unknown
values must be done using a range of values of
the corresponding variable, running the model
repeatedly and selecting the optimal value from
the range that gives model results closest to
observed values.

PolySalt

A simplified version of SahysMod with the
advantage that calculations are made for shorter
time steps (monthly instead of seasonally). The
application principles are similar as those
described before under "SaltCalc".

LeachMod

This model is somewhat similar to SaltCalc.
On the one hand the water management options are
fewer (e.g. reuse of drainage or well water for
irrigation do not feature here), but the model is
more modern in the sense that the variable input
for each time step is given in a table so that
the calculations over all the time steps are done
in one go. Moreover, by inserting the observed
values of soil salinity in the data table, the
model optimizes the leaching efficiency of the
soil automatically.


