Abstract:
In Tunisia, Kalâat El Andalous irrigated district i
s one of the most affected areas by
salinization. The objective of this study was to pr
edict the root zone salinity (over 10
years) in this area using the SaltMod simulation mo
del for subsurface drainage system.
SaltMod is based on water balance, salt balance mod
el, and seasonal agronomic aspects.
In the pilot area, irrigated vegetables crops such
as tomato (
Lycopersicum esculentum
),
melon (
Cucumis mela
) and
squash (
Cucurbuta maxima
) occupy the field during summer
and rainfed wheat during winter.
The model predicted more or less similar values of
electrical conductivity in the root zone. Highest v
alue of electrical conductivity reached
during the irrigation season was 7.7 dS m
-1
. Following the fall rains, there was a decrease
of the soil salinity when the average minimum value
of electrical conductivity was 3.1 dS
m
-1
. The simulation also showed that decreasing the de
pth of the drain did not
change significantly the root zone salinity. The de
pth of the drain could be reduced to 1.6
m without any damage to crops. There was a slight r
eduction in drainage flow when the
depth of the drain changed from 1.8 m to 1.2 m. Dec
rease of the drain depth decreased
water table level. There was no variation in root z
one salinities due to change in drain
spacing. The predicted drainage flows were related
to the occurrence of irrigation and
rainfall. In this study, calibration of SaltMod for
water-salt balance parameters proved
the validity of the model for the local conditions.
Keywords:
Drain discharge, Irrigation, Salinity, Subsurface
drainage, Water table.
