EFFECT
OF THE IRRIGATION CANAL NETWORK ON SURFACE AND GROUNDWATER INTERACTIONS
IN THE LOWER VALLEY OF THE CACHAPOAL RIVER, CHILE
José Luis Arumí1*, Diego Rivera1,
Eduardo Holzapfel1, Peter Boochs2, Max Billib2,
and Alexander Fernald3
ABSTRACT
Agricultural production of
high value crops in Chile's
Central Valley is highly dependent on surface and groundwater
resources. They are connected and together form an integrated hydrological
system, the individual components of which have to be studied. This
research is addressed to answering two questions: 1) to what extent
do irrigation and canal seepage contribute to groundwater
recharge and 2) what is the influence of the interactions between
the Cachapoal River and ground water. The study was carried
out from 2003 to 2007
in Peumo
Valley (34.3°
S, 71.3° W). In winter, the irrigation canal network intercepts
and diverts surface runoff, which flows to flat areas and recharges
groundwater. In summer, infiltration from the canals recharges the
aquifer directly and partially compensates for water uptake from
plants and evaporation. The effects of both interactions keep groundwater
at a relatively constant level over the whole year. The water balance
of the valley is strongly affected by agricultural practices, groundwater
recharge mainly originating from irrigation loss (22%) and canal
seepage (52%). It is important to know how management decisions,
such as change in irrigation practices or canal lining, can affect
the hydrological system and agricultural production within the valley.
Key words: agriculture, Chile,
groundwater, irrigation seepage, MODFLOW, surface water-groundwater
interactions
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1
Universidad
de Concepción, Facultad de Ingeniería Agrícola, Av. Vicente Mendez 595, Chillán, Chile. *Corresponding author (jarumi@udec.cl
)
2 University of Hannover, Institute of Water
Resources Management, Hydrology and Agricultural Hydraulic Engineering
(WAWI), Leibniz, Appelstr. 9A, 30167, Hannover,
Germany.
3 New Mexico State University, Department
of Animal and Range Sciences, PO Box 30003, MSC 3-I, Las Cruces, New Mexico,
USA.
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