Geoscience Reference
In-Depth Information
Fig. 17.1
Changes in chloride concentrations in the Israeli coastal aquifer (Gvirtzman
2002
)
agriculture; natural seaward flow was reversed, creating conditions of a closed
basin with no outlet to the Mediterranean Sea. In the 1960s, an additional source of
irrigation water was from the Sea of Galilee, with a chloride concentration of
210-250 mg/L. While the average increase in groundwater chloride concentration
between the years 1950-1960 was about 1.5 mg/L/year, the annual chloride input
after 1970, using the new source of irrigation water, reached 2.0 mg/L/year. Since
the early 1990s, treated sewage water with a chloride content ranging between 190
and 330 mg/L partially replaced the Sea of Galilee irrigation water. Over a 30-year
period, and despite the fact that the aquifer salt concentration was diluted by an
average rainfall precipitation in the area ranging from 350 to 500 mm/year, the
chloride concentration of the coastal aquifer increased from 120 to 180 mg/L
(Fig.
17.1
).
Many other locations around the world are experiencing irreversible saliniza-
tion of groundwater following irrigation. For example, in a comprehensive review
on the impact of agricultural practices on groundwater salinity, Suarez (
1989
)
notes that irrigation practices have led to groundwater salinization in the San
Joaquin Valley, upper Rio Grande, and Maricopa County (USA).
Groundwater salinization under downward flow of rainwater may also occur
from nonirrigated agricultural practices that cause natural leaching. Ferguson and
Bateridge (
1982
) determined the balance of salts in cultivated and native glacial
till soils from north-central Montana (USA), estimating that after 50 years of
