TY - JOUR
T1 - Distinct stores and the routing of water in the deep critical zone of a snow-dominated volcanic catchment
AU - White, Alissa
AU - Moravec, Bryan
AU - McIntosh, Jennifer
AU - Olshansky, Yaniv
AU - Paras, Ben
AU - Andres Sanchez, R.
AU - P A Ferré, Ty
AU - Meixner, Thomas
AU - Chorover, Jon
N1 - Publisher Copyright:
© 2019 BMJ Publishing Group. All rights reserved.
PY - 2019/11/18
Y1 - 2019/11/18
N2 - This study combines major ion and isotope chemistry, age tracers, fracture density characterizations, and physical hydrology measurements to understand how the structure of the critical zone (CZ) influences its function, including water routing, storage, mean water residence times, and hydrologic response. In a high elevation rhyolitic tuff catchment in the Jemez River Basin Critical Zone Observatory (JRB-CZO) within the Valles Caldera National Preserve (VCNP) of northern New Mexico, a periodic precipitation pattern creates different hydrologic flow regimes during spring snowmelt, summer monsoon rain, and fall storms. Hydrometric, geochemical, and isotopic analyses of surface water and groundwater from distinct stores, most notably shallow groundwater that is likely a perched aquifer in consolidated collapse breccia and deeper groundwater in a fractured tuff aquifer system, enabled us to untangle the interactions of these groundwater stores and their contribution to streamflow across 1 complete water year (WY). Despite seasonal differences in groundwater response due to water partitioning, major ion chemistry indicates that deep groundwater from the highly fractured site is more representative of groundwater contributing to streamflow across the entire water year. Additionally, the comparison of streamflow and groundwater hydrographs indicates a hydraulic connection between the fractured welded tuff aquifer system and streamflow, while the shallow aquifer within the collapse breccia deposit does not show this same connection. Furthermore, analysis of age tracers and oxygen (δ18O) and stable hydrogen (δ2H) isotopes of water indicates that groundwater is a mix of modern and older waters recharged from snowmelt, and downhole neutron probe surveys suggest that water moves through the vadose zone both by vertical infiltration and subsurface lateral flow, depending on the lithology. We find that in complex geologic terrain like that of the JRB-CZO, differences in the CZ architecture of two hillslopes within a headwater catchment control water stores and routing through the subsurface and suggest that shallow groundwater does not contribute significantly to streams, while deep fractured aquifer systems contribute most to streamflow.
AB - This study combines major ion and isotope chemistry, age tracers, fracture density characterizations, and physical hydrology measurements to understand how the structure of the critical zone (CZ) influences its function, including water routing, storage, mean water residence times, and hydrologic response. In a high elevation rhyolitic tuff catchment in the Jemez River Basin Critical Zone Observatory (JRB-CZO) within the Valles Caldera National Preserve (VCNP) of northern New Mexico, a periodic precipitation pattern creates different hydrologic flow regimes during spring snowmelt, summer monsoon rain, and fall storms. Hydrometric, geochemical, and isotopic analyses of surface water and groundwater from distinct stores, most notably shallow groundwater that is likely a perched aquifer in consolidated collapse breccia and deeper groundwater in a fractured tuff aquifer system, enabled us to untangle the interactions of these groundwater stores and their contribution to streamflow across 1 complete water year (WY). Despite seasonal differences in groundwater response due to water partitioning, major ion chemistry indicates that deep groundwater from the highly fractured site is more representative of groundwater contributing to streamflow across the entire water year. Additionally, the comparison of streamflow and groundwater hydrographs indicates a hydraulic connection between the fractured welded tuff aquifer system and streamflow, while the shallow aquifer within the collapse breccia deposit does not show this same connection. Furthermore, analysis of age tracers and oxygen (δ18O) and stable hydrogen (δ2H) isotopes of water indicates that groundwater is a mix of modern and older waters recharged from snowmelt, and downhole neutron probe surveys suggest that water moves through the vadose zone both by vertical infiltration and subsurface lateral flow, depending on the lithology. We find that in complex geologic terrain like that of the JRB-CZO, differences in the CZ architecture of two hillslopes within a headwater catchment control water stores and routing through the subsurface and suggest that shallow groundwater does not contribute significantly to streams, while deep fractured aquifer systems contribute most to streamflow.
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U2 - 10.5194/hess-23-4661-2019
DO - 10.5194/hess-23-4661-2019
M3 - Article
AN - SCOPUS:85075279560
SN - 1027-5606
VL - 23
SP - 4661
EP - 4683
JO - Hydrology and Earth System Sciences
JF - Hydrology and Earth System Sciences
IS - 11
ER -