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1349811 
Journal Article 
Groundwater geochemistry of the Chihuahua City region in the Rio Conchos Basin (northern Mexico) and implications for water resources management 
Mahlknecht, J; Horst, A; Hernandez-Limon, G; Aravena, R 
2008 
Yes 
Hydrological Processes
ISSN: 0885-6087
EISSN: 1099-1085 
22 
24 
4736-4751 
WOS:000261218900007 
The Chihuahua City region, located in the semiarid-arid
northern highlands of Mexico, has experienced intensive groundwater abstraction during the last
40 years to meet water demands in the region. A geochemical survey was carried out to investigate
the evolution from baseline to modern conditions of a 130-km flow path including the El Sauz-
Chihuahua-Aldama-san Diego de Alcala regions. The research approach included the use of major
chemical elements, chlorofluorocarbons and environmental isotope (O-18, H-2, C-13 and C-14)
tracers. Stable isotopes indicate that groundwater evolves front the evaporation of local
rainfall and surface water. Groundwater located at the lower end of the flow section is Lip to
6000 years old and older groundwater in the order of 9000 years BP was found in a deep well
located in the upper part of the flow system, implying contribution from a neighbour basin. The
background groundwater chemistry upstream of Chihuahua City results from feldspar weathering.
Beyond Chihuahua City the chemical conditions are strongly modified owing to disposal of sewage
from public and industrial water supplies into the Rio Chuviscar. subsequent allocation of this
water to agricultural irrigation areas and direct infiltration under the river bed. As a
consequence, anions like chloride and sulphate are mainly related to surface sources. Nitrate is
controlled in part by sewage from public Supply and industry and in part by agricultural
practices. Arsenic and fluoride are related to weathering of rock formations of local mineralized
ranges and subsequent enrichment of the basin-fill by magmatic processes. The results Of this
study have implications for groundwater management in an and region that depends entirely on
groundwater for domestic. industrial and a,,agricultural water consumption. Copyright (C) 2008
John Wiley & Sons. Ltd. 
groundwater geochemistr; isotope hydrology; radiocarbon; chlorofluorocarbons; anthropogenic effects; arsenic; semiarid regions; Rio Conchos; Chihuahua; Mexico