Publications

@article{Wlostowski2020,

title = {Signatures of Hydrologic Function Across the Critical Zone Observatory Network},

author = {Adam N. Wlostowski and Noah Molotch and Suzanne P. Anderson and Susan L. Brantley and Jon Chorover and David Dralle and Praveen Kumar and Li Li and Kathleen A. Lohse and John M. Mallard and Jennifer C. McIntosh and Sheila F. Murphy and Eric Parrish and Mohammad Safeeq and Mark Seyfried and Yuning Shi and Ciaran Harman},

doi = {10.1029/2019WR026635},

year  = {2020},

date = {2020-10-18},

journal = {Water Resources Research},

volume = {57},

number = {3},

abstract = {Despite a multitude of small catchment studies, we lack a deep understanding of how variations in critical zone architecture lead to variations in hydrologic states and fluxes. This study characterizes hydrologic dynamics of 15 catchments of the U.S. Critical Zone Observatory (CZO) network where we hypothesized that our understanding of subsurface structure would illuminate patterns of hydrologic partitioning. The CZOs collect data sets that characterize the physical, chemical, and biological architecture of the subsurface, while also monitoring hydrologic fluxes such as streamflow, precipitation, and evapotranspiration. For the first time, we collate time series of hydrologic variables across the CZO network and begin the process of examining hydrologic signatures across sites. We find that catchments with low baseflow indices and high runoff sensitivity to storage receive most of their precipitation as rain and contain clay-rich regolith profiles, prominent argillic horizons, and/or anthropogenic modifications. In contrast, sites with high baseflow indices and low runoff sensitivity to storage receive the majority of precipitation as snow and have more permeable regolith profiles. The seasonal variability of water balance components is a key control on the dynamic range of hydraulically connected water in the critical zone. These findings lead us to posit that water balance partitioning and streamflow hydraulics are linked through the coevolution of critical zone architecture but that much work remains to parse these controls out quantitatively.},

keywords = {catchment sensitivity, critical zone structure, ERCZO, meta-analysis, water balance},

pubstate = {published},

tppubtype = {article}

}

@article{Kim2017,

title = {Controls on solute concentration‐discharge relationships revealed by simultaneous hydrochemistry observations of hillslope runoff and stream flow: The importance of critical zone structure},

author = {Hyojin Kim and William E. Dietrich and Benjamin M. Thurnhoffer and Jim K. B. Bishop and Inez Y. Fung},

doi = {https://doi.org/10.1002/2016WR019722},

year  = {2017},

date = {2017-01-27},

journal = {Water Resources Research},

volume = {53},

number = {2},

pages = {1424-1443},

abstract = {We investigated controls on concentration‐discharge relationships of a catchment underlain by argillite by monitoring both groundwater along a hillslope transect and stream chemistry. Samples were collected at 1–3 day intervals over 4 years (2009–2013) in Elder Creek in the Eel River Critical Zone Observatory in California. Runoff at our study hillslope is driven by vadose zone flux through deeply weathered argillite (5–25 m thick) to a perched, seasonally dynamic groundwater that then drains to Elder Creek. Low flow derives from the slowly draining deepest perched groundwater that reaches equilibrium between primary and secondary minerals and saturation with calcite under high subsurface pCO2. Arriving winter rains pass through the thick vadose zone, where they rapidly acquire solutes via cation exchange reactions (driven by high pCO2), and then recharge the groundwater that delivers runoff to the stream. These new waters displayed lower solute concentrations than the deep groundwater by less than a factor of 5 (except for Ca). Up to 74% of the total annual solute flux is derived from the vadose zone. The deep groundwater's Ca concentration decreased as it exfiltrates to the stream due to CO2 degassing and this Ca loss is equivalent of 30% of the total chemical weathering flux of Elder Creek. The thick vadose zone in weathered bedrock and the perched groundwater on underlying fresh bedrock result in two distinct processes that lead to the relatively invariant (chemostatic) concentration‐discharge behavior. The processes controlling solute chemistry are not evident from stream chemistry and runoff analysis alone.},

keywords = {concentration-discharge relationships, critical zone structure, ERCZO, simultaneous observations of ground water and stream water},

pubstate = {published},

tppubtype = {article}

}