Monday, May 7, 2012

Preparing for Spring Snowmelt (by Larry Hinzman)

I was able to join the hydrology team of the first day of well installation.  As most experienced researchers know, persistence and exertion will eventually prevail over adversity, and research in the Arctic sees all that and more.  We continue to be blessed with pretty good weather, but the day was overcast, giving flat light and making it difficult to distinguish variations in the snow.  Days like that can give the feeling of walking around inside a white balloon as one cannot separate the sky from the ground. It had snowed Tuesday, Wednesday and Thursday, but the 16 mph winds were not high enough to lift the new snow more than a few inches off the ground.  This is often called siltation snow, and while not pleasant, it is not unusual nor hazardous.  The risk of white-out conditions does remain following new snow if winds increase to levels of about 35 mph or greater.   Our pre-work safety plan included a discussion on watching the horizon and power poles in the distance.  If visual contact with the powerline becomes tenuous, it is time to pack up and call it a day.  

Spring is coming to Barrow and the snow was also warming.  It was a bit softer and stickier as compared to our April trip, but snowmelt is only a few weeks away.   Snowmelt causes a huge switch in the surface energy balance, it is the dominant hydrologic event, and a tremendous change in all biological activities.  We need to make certain our pre-snowmelt measurements are completed to accurately document the changes that occur between May and June.

Installation of soil water wells was a slow process as drilling into cold frozen ground is difficult.  We were fortunate to have the assistance of Alexander Kholodov of the UAF Geophysical Institute Permafrost Lab with their array of drilling equipment.  Alex used a very large hand-held drill called a Hole Hawg driving specially designed permafrost augers to bore the 1 m holes, which will permanently anchor the wells and reduce frost jacking.  Anna Liljedahl designed the casing with obstructions at the bottom to hopefully maintain a secure foundation in the permafrost. Pipes and stakes placed into freezing ground tend to jack upward over the years as the active layer freezes hard near the surface in the Autumn and then expands upward.  We need to measure the water levels in the wells with millimeter accuracy to allow measurement of groundwater gradients.   This is particularly difficult in areas with such low gradients.  On our previous trip to the BEO, we installed eight benchmarks drilled and driven 9 feet into the permafrost, to which we also added jacking prevention.  Each spring, we will conduct an elevation survey of all benchmarks and wells to ensure correct elevation measurements of the water levels.

Alexander Kholodov of UAF drills 1 m holes into the permafrost
for installation of soil water wells.
Anna Liljedahl and Stan Wullschleger discuss the experimental design
of soil water measurements.

Cathy Wilson records field observations on well placement.
Anna has installed capacitance probes in each well.  This is a new sensor for us, but appears promising for continuously measuring water levels while also being immune to freezing.  This is quite different from the pressure transducers hydrologists have used for the past several decades.

Anna Liljedahl will use a newly improved capacitance probe for continuous measurement of water levels.

Craig Ulrich of LBNL was again a key field party member.  Craig used a differential gps to precisely position each well.  As one can imagine, with continuous snowcover, it would be impossible to know where polygon ridges and troughs are without such equipment.

The NGEE program is fortunate to have the dedicated leadership of our Program Director Stan Wullschleger.  Stan has been central to development of the research plan, and now he is integral to project implementation.  He is the liaison among all researchers, our logistical providers, the general public and our program managers, and has preformed admirably in all cases.  And, he is a hearty field researcher.  Installation of trail mat is essential to protection of the tundra from the impact of dozens of researchers.   Stan has again taken the lead in coordinating and laying out the trail mat.  We will have kilometers of trail mat and installation must occur while snowmachines can still be used to distribute the pallets of mat sections.  But, laying out these trails is still hard work requiring long days of backbending labor.   Speaking on behalf of all those who will use these trails, we appreciate Stan's leadership and his willingness to share his muscles as well as his intellect