Investigation of the Origin of Hueco Bolson and Mesilla Basin Aquifers (US and Mexico) with Isotopic Data Analysis

Abstract

An important tool to identify the origin of a groundwater resource is the use of isotopic signatures. Isotopic signatures give us the age of water and provide information as to the water’s origin, potential transit at geologic structures, source of salinization, and possible recharge points. The purpose of this study was to collect and analyze well samples to evaluate isotopic tracers (δ18O and tritium) in the transboundary Conejos-Médanos/Mesilla aquifer located between the US and Mexico. This new analyzed information was compared with the isotopic information available in the US Mesilla and US-MX Hueco basins generated by previous works, which described the common origin of the Hueco Bolson and Mesilla Basins aquifers. This study used isotopic analysis to validate the theory of the original formation and interconnectivity of both transboundary basins. This research presents new data of δ18O and tritium, and a comparison with previous published data from other workers, versus the known global meteoric water line (GMWL) and the Rio Grande evaporation line (RGEL). Results show that the groundwater at the transboundary aquifer features an evaporated isotopic signal, which is consistent with referenced published data that discusses the geologic history of aquifer formations at the studied area. This study is important because isotopic studies from the area were nonexistent and because isotopic data can explain recharge scenarios that relate to groundwater quality.

Advances in Transboundary Aquifer Assessment

“…In "Investigation of the origin of Hueco Bolson and Mesilla Basin Aquifers (US and Mexico) with isotopic data analysis" [16], Garcia-Vasquez et al use the isotopic tracers δO 18 and tritium to validate an interconnection between the Mesilla (U.S. portion) and Hueco Bolson aquifers. They combine new data from the Mexican portion of the Mesilla/Conejos-Médanos aquifer with results from the U.S. side of the aquifer [17].…”

“…These more focused studies [14][15][16] contributed to a synthesis and refinement of the water budget and hydrogeologic framework model for the Mesilla/Conejos-Médanos aquifer [12]. In "Mesilla/Conejos-Médanos Basin: U.S.-Mexico transboundary water resources", Robertson et al use an updated hydrogeologic framework, a binational waterlevel map, and previously reported aquifer property assumptions to estimate potentially recoverable fresh to slightly brackish groundwater in the Mesilla portion of the Basin at about 82,600 cubic hectometers (hm 3 ), largely in agreement with previous estimates.…”