USE OF SCHLUMBERGER ARRAY VES AND GEOMORPHOMETRIC TECHNIQUES TO CHARACTERIZE THE CAÑÓN DE SANTA CLARA ALLUVIAL FAN, CHIHUAHUA, MÉXICO

The Valle El Sauz Encinillas (VESE) is located 92 km north of Chihuahua City, Mexico. A lack of public available hydrogeological data still prevails in the area despite being the principal aquifer feeding Chihuahua City. The goals of this study are: 1) determination of the alluvial fan geoelectrical units via electrical-resistivity soundings, and 2) geomorphometrical analysis of four alluvial fans (and sub-basins) in the area.

The Basin and Range system prevailing in central Chihuahua formed closed lacustrine basin systems in advanced extinction processes. The VESE aquifer is located in alluvial Quaternary sediments, with varying granulometry, reaching an assumed thickness of 600 meters at the center of the valley.

The largest alluvial fan in the VESE is located at the mouth of the Cañón de Santa Clara, and intersects the playa-lake deposits of the Laguna de Encinillas. This fan has a surface of 73.2 km² and an average slope of 0.437°. The geomorphometrical analyses permit a comparison between these alluvial fans and those in Death Valley, California, USA. The alluvial fans in both areas show a similar behavior in all plots.

Twenty vertical electrical resistivity soundings (Schlumberger array, with AB/2 distance of 400 m) were performed in the alluvial fan. The basement and four other geoelectrical units were identified based on the interpretation of the apparent resistivity curves.