Salinization in coastal aquifers of arid zones: An example from Santo Domingo, Baja California Sur, Mexico
Por:
Cardona A., Carrillo-Rivera J.J., Huizar-Álvarez R., Graniel-Castro E.
Publicada:
1 ene 2004
Resumen:
Groundwater quality in the Santo Domingo Irrigation District area in Baja California Sur, Mexico, indicates the presence of various salinization processes, (1) the geological matter of marine origin comprising the aquifer material suffers diagenetic effects due to its interaction with groundwater of low salinity, (2) the effects of intensive agriculture practices produces effluents that infiltrate to the saturated zone, and (3) the extraction of groundwater causes modifications in the natural flow system induces lateral flow of seawater from the coast line. However, groundwater management has been carried out with the belief that the latter is the main source of salinization. This has resulted in a policy of installing wells increasingly far from the coast, which is not solving the problem. Irrigation-return and seawater that remains in the geological units have been identified as major sources of salinization. Controls should be imposed when installing wells in contact with clayey units that form the base of the aquifer. Extracted groundwater consists of a mixture of (1) groundwater of relatively low salinity that circulates in the aquifer and (2) an extreme member with salinity different to seawater contained mainly in formations that have low permeability, which limits the aquifer underneath. The geochemistry of carbonates and cation-exchange reactions (both direct and reverse) control the concentration of Ca, Mg, Na, and HCO3, as well as pH values. The concentrations of dissolved trace elements (F, Li, Ba, Sr) suggest that the extreme saline member is different from the average seawater composition. A distinction between the salinization caused by farming practices and that blamed on seawater is defined by the use of NO3.
Filiaciones:
Cardona A.:
Ciencias de la Tierra, Facultad de Ingeniería, Zona Universitaria, 78290 San Luis Potosí, Mexico
Carrillo-Rivera J.J.:
Instituto de Geografía, UNAM, Coyoacán, CU, 04510, Mexico
Huizar-Álvarez R.:
Instituto de Geología, UNAM, Coyoacán, CU, 04510, Mexico
Graniel-Castro E.:
Facultad de Ingeniería, UADY, Apartado Postal No. 150, Cordemex Merida, Yucatan, Mexico
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