Monday, July 13, 2015

Hydrology Tracer Study Gets Underway...

Nathan Wales, NGEE Hydrology Masters Student from New Mexico Tech, working with LANL NGEE hydrologists Brent Newman and Cathy Wilson, is putting the finishing touches on the deployment of water sampling and measurement equipment that will be used to carry out a tracer experiment at the Barrow Environmental Observatory NGEE Arctic intensive field site. The NGEE team deployed 75 macro-rhizons over the past 2 days, in order to collect soil water samples at multiple soil depths across two polygons types in order to track and quantify the role of polygon surface and frost table micro-topography in controlling subsurface horizontal flow of water in the landscape. 

Nathan installs a collar (green tube) around a well hole to ensure that the dilute sodium bromide tracer cannot flow into the well hole through surface water pathways during rain events.  Brent Newman (background) installs the macro-rhizons at 15cm, 25 cm and 35 cm below the ground surface. Subsurface soil water samples collected with the macro-rhizons will be analyzed in the BARC laboratory to quantify how fast the tracer applied at the surface of the high center polygon will infiltrate into the soil and move sideways through the subsurface down to the subsoil in the troughs.

 Most global climate models assume that all subsurface water flux is one dimensional, in the vertical direction; driven into the soil by gravity and negative soil water pressures (suction) during rainfall, and drawn out of the soil and into the atmosphere by evaporation and plant transpiration. But analysis of new NGEE in-situ geochemical data, and analysis of seasonal inundation patterns using remote sensing data, both suggest that horizontal water flow, well after snow melt, may be important in determining the spatial distribution of chemical constituents and biogeochemical processes in low relief Arctic coastal plain environments. Water level and tracer data will be used together to inform NGEE’s Arctic Terrestrial Simulator, that will be used to help interpret the tracer study results and improve our understanding of water and chemical constituent transport in the Arctic. 

Nathan programs the water level sensor to record water levels every 10 minutes in the shallow (1m deep) wells deployed across the polygons.
UTEP researchers, Florencia and Steve, visit the low center polygon tracer study site to photograph NGEE wells for Craig Tweedie’s BAID GIS project. BAID archives and serves GIS and other spatial data for all research activities in the BEO. 

Golden plover inspects experimental design.