DEVELOPMENT OF A GEOCHEMICAL FRAMEWORK TO CHARACTERIZE COMPLEX AQUIFER RECHARGE-DISCHARGE RELATIONS: TRANS PECOS, TEXAS, USA

Effective water management requires that the hydraulic recharge-discharge relations that manifest at springs (and other outlets contributing to river flows) be understood well enough to assess impacts of changes in recharge and/or groundwater withdrawals. Developing a geochemical framework is a promising approach because it can highlight subtle differences in flow regimes and flow paths that are not as easily discerned through other methodologies, such as dye tracer tests and potentiometric surface mapping. Previous studies have established that multiple source areas contribute to spring discharge in the San Solomon Springs system in Trans Pecos Texas. This spring system provides an ideal location to develop and test a geochemical framework that includes an expanded isotopic approach. Nontraditional isotopes (i.e., boron-11, nitrogen-15 of nitrate, and triple oxygen isotopes) are integral to the development of this framework. A multivariate statistical approach has been used to identify multiple source areas to this multi-outlet spring system. Further development of this promising multi-component statistical approach has been used to enhance characterization of complex multi-outlet spring recharge-discharge relations and to better understand how the spring system relates to the regional surface-water/groundwater flow regime.