Category Archives: 2013 (12/09) Gauge Boxes and Trickling Streams

Gauge Boxes and Trickling Streams

Dec. 9, 2013

The temperatures are slowly getting warmer as we near austral summer and a few of the streams have started to flow. Generally the melt season is late November- mid January, when it creeps just slightly above freezing temperatures and the glaciers release a pulse of meltwater down into the valleys through various stream channels that have formed over time, releasing the water into lakes that will refreeze in February towards austral autumn. We will track the volume and flow of the meltwater and measure various aspects of the water chemistry of these streams throughout the summer season. The melt happened quite quickly; one week everything was frozen and quiet and the next week I could hear rushing water within the glaciers, as melt water rushed down the cracks and under the surface of the snow.

While the sound of the water near the glaciers is actually surprisingly loud, that water is still taking a bit of time to actually flow down the valley and the amount of water entering the steams is still low at the moment. Within another week though, considering how fast the melt season started, it should start to surge even more quickly.

DSCN1444The melt season has begun!

This past week was spent replacing some of the 10+ year old gauge boxes that monitor steam flow of the different creeks that flow from glaciers into Lake Fryxell. Each of the gauge boxes is a large wooden box with wiring and probes that extend to a nearby stream to measure temperature and conductivity, along with a conoflow that measures the depth of the stream.

DSCN1476bHiking out to one of the gauge boxes.

IMG_7962bOne of the old gauge boxes with a small stream starting to flow behind it

I think the concept behind the conoflow depth measurements are pretty cool- in order to measure the depth of the stream automatically (every 1-15 minutes), a nitrogen tank inside the gauge box releases a bubble of nitrogen through a long tube that extends to the bottom of the streambed. Since pressure increases with water depth, there is less resistance to ‘pushing’ the bubble out of the tube when the tube only has 5 centimeters of water flowing over it than when there is 30 centimeters of water flowing over it, and so that measure of pressure/resistance can be converted into an estimate of the actual depth of the stream at that point and recorded on a computer chip. Many other methods of measuring stream depth involve instruments with liquids that aren’t practical to a cold environment like Antarctica, but the constant flow of nitrogen gas being released through the tube helps to keep the tubing free from ice that might otherwise build up inside.

Since the gauge boxes are made of wood, we replaced some of the older ones this week to ensure that they don’t get too weathered (it’s quite windy here) and break down over the winter season. We broke down the old boxes, set up new, sturdier ones, and carted all of the old pieces back to our fieldcamp F6 where they’ll be piled together and picked up by a helicopter at the end of the summer season. Once the streams start flowing at a higher level later in the season we’ll be busy sampling the water quality at each stream (may of them take a while to hike to, while we will take a helicopter to travel to the streams farther away from our valley) so it was good to get all of these new boxes set up ahead of the busy season.

8750_10101633994843121_1375042920_nTaking apart the old boxes

Attempting to be a Spartan from 300 whilst taking apart the old boxes…

1476455_10101628313862851_19862357_nThe new gauge boxes we assembled. All of the instrumentation is inside, while tubing leads down to the stream, which isn’t yet flowing at this snow-covered site.

1459342_10101634000456871_911566064_nVictory pose at the site of the last gauge box we built

This upcoming week we’re flying to a few different valleys to start measuring the streams, so I’ll update on what it is we do exactly at each stream sometime next week. Stay warm!