The Impact of Irrigation on Ground Water Quality

Carter, D.L. (1980) The Impact of Irrigation on Ground Water Quality. pp. 13-20. In: Proc. 1980 Spec. Conf. Irrigation and Drainage - Today's Challenges. USA-ID-Boise, 1980/07/23-25. ASCE.

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Abstract

Most soils in arid regions contain significant quantities of water
soluble salts. When these soils are brought under irrigation, soluble
salts are leached into the ground water. The salt leaching rate and
the annual salt outflow depends upon the quantity of water applied in
excess of evapotranspiration each irrigation season. The total quantity
of salt leached from a Portneuf silt loam, 5 m deep, was 70 metric
tons/ha. The first 14 cm of water passing out the bottom of the soil
carried 38 metric tons of soluble salt/ha of soil into the ground
water. Essentially all of the residual soluble salt was leached into
the ground water after 30 cm of water/m of soil depth had passed from
the soil as leachate, regardless of the number of irrigation seasons
required for that amount of leaching. After the residual salts were
removed, the salt concentration in the newly irrigated soil was the
same as in Portneuf silt loam that had been irrigated for 70 years with
a high leaching fraction. Subsequent salt outflow from the soil into
the groundwater was directly related to the quantity of water leaching
through the soil, indicating that more minerals dissolved with more
leaching, but the salt concentration in the soil did not change significantly
with the leaching fraction. Salt outflows from both newly
irrigated and old irrigated lands can be predicted based upon prevailing
laNd conditions and given irrigation practices. The impact of these
outflows upon ground water quality can be estimated.

Item Type:	Conference or Workshop Item (Paper)
NWISRL Publication Number:	0445
Subjects:	Water > Water quality Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:57
Last Modified:	01 Feb 2017 22:53
Item ID:	1018
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/1018