Crescent Stream

Hey Everyone.  Sorry I have been slacking lately with the posts.  Things have become quite busy for me as I expected now that my Professor has made it out here.

As my buddy pointed out, I should probably describe what my thesis project is exactly.  This may be a bit dense, but here it goes anyways.  In 2012 my professor noticed that the water flowing in Crescent Stream looked like chocolate milk, just filled with sediment.  This is very unusual for any stream down here, and is a good indication that something interesting is going on upstream.  He and a colleague headed up the stream and found some huge bank failure features along with a tunnel where part of the stream disappeared below the bank and exited the bank back into the stream channel about 10 m below.  This bank failure was termed a thermokarst feature, which is any geomorphic feature caused by the thawing of permafrost.  The permafrost in the soil had been holding the bank together at a steep angle, and the melting of the permafrost decreased the strength of the soil enough that the bank failed and deposited a bunch of sediment and boulders into the stream.

This sediment loading is very important in the greater context of the ecosystems of the Dry Valleys.  Some of the only life that exists in the Dry Valleys is stream algae, and lake microbes (unfortunately not a fish to be found...).  Any large increase in sediment load to a stream will have impacts on both of these communities.  The stream algae will be scoured and buried with new sediment added to the stream.  The water exiting the stream into the lake will be loaded with suspended sediment.  This means that the water in the lake within the vicinity of the stream inlet will be less transparent than usual due to the sediment in the water.  This then reduces the amount of sunlight (energy) that can enter the lake ecosystem.

So, they surveyed the ground surface of this thermokarst feature in 2012 using technology called a Terrestrial Lidar Scan (TLS).  This is a really cool piece of technology.  It is a ground surface survey that utilizes a unit mounted on a tripod that shoots a laser around in a 360 field of view.  The data that it collects is tens of millions of ground points that have an x,y,z coordinate in the global coordinate system.  The resolution of points is around 1 point per 0.5 cm which is insane.  Anyways this allows us to have a 3D elevation model of the true ground surface that we can do a variety of analysis on.  This same survey data in the same location has now been collected in 2012, 2013, 2014, and coming soon 2015 (that's me!).  I am using tools in a piece of software called Cloud Compare along with ArcGIS to compare the surveys from year to year.  Using this software I am able to estimate the volume of sediment that has been added to the stream from this feature.

On top of the TLS data, this year I will also be sampling the sediment in the stream.  We will be doing pebble counts (sounds as exciting as it really is...), and sieving of sediment.  This will give me an idea of what the size distribution of the sediment is of the bank that failed and we can see what the impact has been on the surface sediment size distribution of my stream.  For a baseline condition, I need to compare my impacted stream with a stream that hasn't seen this type of sediment loading.  Conveniently, my stream has a west branch (the impacted one) and an east branch (non-impacted).

Ultimately the goal is to quantify the impact of the thermokarst feature on the physical properties of the stream.  This will help show what the future implications could be on other streams if permafrost degradation is expected.

Well that is enough of the gory details of my research, back to my day to day.  Friday we had some new people join us at F6 camp.  They study soil microbes in the Dry Valleys and are known as the "worm herders" (great nickname).  They are from all over and are great to have around.  We helped out with one of their experiments where they pumped a bunch of water up to a tank and soaked one of their test plots where they study the microbes to study the impacts of moisture.  Here is a picture of the setup.

It was pretty cold, and a lot of waiting around waiting for water to soak into the soil.  We were pretty beat when we got back to camp that night.  When we got home two of the girls had made us all some curry with rice.  It was an awesome meal, and super nice to come home and have something made for us after a long day!

The past two days we went out to crescent stream to perform pebble counts, and set up some soil temperature monitors.  It has been cold, windy, and snowy.  These aren't ideal conditions to be reaching into the stream barehanded to measure the sediment size.  It was cold, but hey I finally felt like I was in Antarctica! 

Today it finally warmed up, and what a welcome sight the sun was!  Those of you in MN probably have no sympathy for me right now.  We spent the entire day working on the ground temperature sensors at Crescent Stream.  We set them up near the thermokarst feature I am studying.  We put one on the east bank and one on the west bank.  All of the bank degradation has been seen on the east bank, and we are curious to see if the orientation of the bank with respect to the suns orbit influences the temperature of the soil at different depths.  

Here is a cool picture of my stream going around a bend.  This curved section is part of the bank that failed in 2012!

We came home late again around 8:30 pm and luckily someone had made us burritos!  They were the perfect cap to a great day of work.  I think I am going to go on a walk tonight after I write this to just relax for a bit.  Here is the photo of the cribbage board I made that Natalie requested.  I don't remember if I explained where we got the board, but we found it on a hike.  It had fallen off of a piece of cargo that must of weighted 475 lbs and was headed to the Lake Hoare Camp.  It would have been more fitting if it said F6, but oh well.  I finally won my first game on this board last night!  I'm counting it a win even though I was teaching them how to play...  Down here I have learned you take what you can get haha.

I don't know what the plan is for tomorrow.  I will likely head back up to crescent stream and grab some soil samples to bring back to McMurdo and sieve.  Our plans have been pretty shaken up lately.  There has been a bunch of mechanical trouble with the helicopters, so they haven't had all of them running.  Also, the past two days of wind and snow grounded the helicopters.  Needless to say the helo schedules are backed up, and are messing with everyone's plans.  One of the guys here has been stuck here for three days, and he was shooting for an overnight trip.  My Professor and I were supposed to head to Miers Valley to install a sensor last week, but that got bumped.  We were supposed to go to Don Juan Pond tomorrow, which is the saltiest body of water in the world, but unfortunately it doesn't look like we will be headed there.  Also, the engineer that is flying out with all of the TLS equipment was supposed to fly out tomorrow, but we will see.  I am bummed because helo flights are so damn fun, but my professor seems stressed about getting all of the work done.  I guess we all have our priorities haha.

The idea of a plan out here is pretty comical to me.  Everyday Mike and I hash out a plan for the next couple of days, this plan undoubtedly changes multiple times a day.  Well time for me to enjoy the first nice weather we have had a for a while!