Characterizing Hydrologic Flow Paths and Groundwater-Surface Water Dynamics in a High Elevation Volcanic Catchment

Alissa White1, Bryan Moravec2, Yaniv Olshansky2, Jennifer McIntosh1, and Jon Chorover2

1Department of Hydrology and Atmospheric Sciences 

2Department of Soil, Water and Environmental Science

The University of Arizona, Tucson, AZ

In a high elevation volcanic catchment in the Jemez River Basin Critical Zone Observatory within the Jemez Mountains of Northern New Mexico, a bimodal precipitation pattern creates different hydrologic flow regimes during spring snowmelt and summer monsoon events. Previous work using concentration-discharge relationships and end member mixing analyses has suggested that hydrologic flow paths vary seasonally. This study tests that hypothesis and explores the hydrologic connection of surface water and groundwater from various depths by examining their major ion chemistry and elemental ratios. Downhole neutron probe surveys in three groundwater wells are used to investigate how wetting fronts propagate through the vadose zone via vertical infiltration or lateral subsurface flow. This study also combines observations of groundwater table elevations, streamflow, and precipitation accumulation to test the hypothesis that the highly heterogeneous structure of the subsurface controls its hydrologic response and the response time of surface water and groundwater to precipitation events. I further hypothesize that fracture versus matrix flow controls water chemistry as water transports solutes through different weathering environments as water table depths rise and fall seasonally.