Alissa White, B. Moravec1, Y. Olshansky1, B. Paras, A. Sanchez, L. Ma2, J. McIntosh, T.P.A. Ferré, T. Meixner, and J. Chorover1
Mountain environments contribute substantially to basin aquifers and surface waters in the American Southwest and are an important component of water resources for large population centers downstream. Many of those mountainous environments are composed of complex geology and intricate hydrologic flow paths. One such mountainous system, the Valles Caldera National Preserve in northern NM is the location of the Jemez River Basin Critical Zone Observatory (JRB-CZO). In this talk, analysis of hydrometric, hydrochemical, and isotopic data are used to decipher water routing through the JRB-CZO and investigate groundwater contribution to streamflow, focusing on the role that subsurface structure, particularly fracture density and complicated lithology, plays at different scales. Specific attention to groundwater from two hillslopes with contrasting lithology and subsurface structure informs our understanding of hydrologic response to different hydrologic flow regimes. Distinctions in major ion chemistry and isotope signatures indicate that fractured groundwater dominantly contributes to streamflow. Furthermore, uranium-series and radiogenic strontium isotopes distinguish between fracture and matrix flow in springs and surface waters.