7 July, 2000
July 7, 2000
The lake is still rising - about 2-3 feet per day (1-1.5 inches per hour). It was sunny and warm today. Brilliant weather. There was quite a bit of run off coming off the glacier. I am sure that there was quite a bit of flow in Hidden Creek that feeds the lake. The ice continues to make low thudding sounds. It is still being compressed here.
I spent most of the day looking in the borehole with a video camera. The borehole camera is a small device about the size of a golf ball that includes a lens and a ring of red LEDs (light emitting diodes). It connects to a triaxial cable, the other end of which connects to a digital video camera and a 12V battery. The battery provides the voltage to power the LEDs. There is 200 meters of triaxial cable between the lens/LED system (which I will refer to as the camera) and the video. The camera is lowered into the hole, and the image can be viewed and recorded into the video camera.
As I mentioned in previous journal entries, we think that there is some kind of a drainage feature in our boreholes at a depth of about 115-120 meters. So, our interest is to try to observe this feature and if present, attempt to detect if there is any water flow in the feature. When we lowered the camera we observed a dramatic change in the quality of the water in the hole at 121 meters - it changed from cloudy to clear. This implied that the suspended fine-grained sediment from the upper portion of the borehole was being "siphoned off". We pulled out the camera and attached a string at the end of it, re-lowered the camera, and looked for any motion of the string. Sure enough, there was a slight bit of movement. We had observed a small amount of water flow englacially (water moving inside the glacier at a relatively deep spot).
I would like to add that I have a fellow teacher colleague beginning a similar project here in Alaska a few hundred miles away on the Matanuska glacier. His name is Marvin Geesting and I encourage you to check out his journal entries as well. You will likely see that his project has similarities, and also some differences. In his project, die tracers will be lowered into moulins (drainage holes in the ice). Observations will be made as to where these tracers reappear, samples will be taken, and their change in concentration with time will be measured. This will help them understand the geometry and flow characteristics of the subglacial hydrology. We would like to do the same thing. However, in our case we will not be releasing dyes. Releasing dyes to Hidden Creek Lake to trace its flow patterns as it drains presents a tactical obstacle. The lake would dilute the dye too much. Adding enough dye to overcome this problem is prohibitively expensive. Further, we are in a national park. Adding synthetic tracers to the lake and watching them emerge from the glacier at McCarthy might not go over very well with park visitors.
However, PI (Principal Investigator) Suzanne Anderson is a water chemist. She teaches at U.C. Santa Cruz. She is involved with this project to look for natural tracers that will show a connection between the water in Hidden Creek Lake and the discharge water during the flood. They sampled water from Hidden Creek (the stream that feeds into Hidden Creek Lake), from Hidden Creek Lake, and have been taking numerous samples at regular intervals from the Kennicott River where it emerges from the glacier. All of these samples will be analyzed for a number of chemical parameters to look for any relationship between the waters of Hidden Creek Lake and the outburst flood waters.
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