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.

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.


