Monday, April 28, 2014
Hydrology Team Gets an Early Start…
Although it is still several weeks or more until the spring snowmelt, our team of hydrologists from LANL and UAF are in Barrow this week to collect data that will help us model patterns of water distribution within polygon landscapes. Cathy and Joel from Los Alamos, New Mexico were joined today by Larry and Bob from Fairbanks, Alaska to begin the installation of water sampling stations across the four NGEE Arctic sites on the BEO. Cathy and Larry have worked with members of our modeling team to select the most appropriate locations to install the stations where we will determine saturated hydraulic conductivity later this summer. This is a parameter that our modelers need; it describes the rate at which water moves within soils. It has been a difficult value to glean from the published literature, so we will measure this directly in the field. Aerial images and LiDAR maps of our study site were used to identify likely areas to locate our measurements and John (LBNL) was able to quickly locate those points using high-precision GPS.
Once the locations were identified, it was then a matter of removing snow so we could visually identify the underlying landscape features we were interested in (rims, troughs, and centers). In some cases this required shoveling just a few inches down to polygon rims, but other areas had more snow and required removing 2.5 to 3 feet of hard-packed snow. Fortunately we had only 10 to 12 of these “pits” to dig out during the day. Joel and Bob then drilled holes of varying depths using a one-person auger engine to which we attached a SIPRE coring device. This procedure not only will allow us to prepare for measurements of hydraulic conductivity later in the summer, but also to recover a core of active layer and permafrost soil. These cores were, of course frozen, intact, and we could often remove them with no breaks. Having an intact core will facilitate analysis of thermal properties, soil carbon, and certain aspects of microbiology later in the laboratory. We could make some simple measurements in the field like length of sample and note soil texture and any ice cryostructure. Cathy recorded all this in her field notebook and later transcribed data into computer files. This information will be shared with the larger team and we will make sure that final parameters and interpretation of data is communicated to our modelers.