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| Formato: | Artículo científico |
| Lenguaje: | en |
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Universidad Nacional Autónoma de México
2001
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| Acceso en línea: | https://www.redalyc.org/articulo.oa?id=56840401 |
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- Geophysical characterization of the Etla Valley aquifer, Oaxaca, Mexico R. E. Chávez R. G. Martínez Serrano J. Herrera Barrientos A. Tejero Andrade S. Belmonte E. L. Flores Márquez Ciencias de la Tierra gravity electromagnetic electric tomography groundwater prospecting The water supply needs of the city of Oaxaca have increased considerably over the last twenty years. The aquifer thatproduces 80% of the total water in the region is located in the Valley of Etla, to the NW of the city. Intensive exploitation of theaquifer has reduced the water quality.Basin geometry was estimated from 2.5-D models along four profiles, three W-E and one N-W. The sedimentary thicknessreaches up to 730 m. Gravity and geologic interpretations suggest that the Mesozoic mylonites of the Sierra de Juárez and themetamorphic rocks of the Sierra de Oaxaca underlie the sedimentary infill. The fault pattern controls the tectonic behavior of theregion and groundwater circulation. The Valley of Etla is a steep graben bounded by the Etla and Oaxaca faults.The main aquifers are in the Tertiary and Quaternary horizons. Twenty-three Vertical Electrical Soundings (VES) across thecentral part of the valley yield a thickness of the first aquifer of 20 m to 50 m. Wells in the area were used to control the resistivehorizons and the stratigraphy.Electric tomography studies in the southern portion of the valley showed the base of the first aquifer at 50 m depth. Thewater-bearing sedimentary layers increase in thickness to the north of the valley, following the basement. Electromagneticmeasurements reveal a vadose zone of at least 20 m thickness towards the center of the Valley. Zones of low resistivity were foundin the northern and southern sections of the Valley. A possible contamination is suggested towards the northern portion of the Cityof Oaxaca. 2001 artículo científico 0016-7169 https://www.redalyc.org/articulo.oa?id=56840401 en http://www.redalyc.org/revista.oa?id=568 Geofísica Internacional application/pdf Universidad Nacional Autónoma de México Geofísica Internacional (México) Num.4 Vol.40