4 July, 2000

July 4, 2000

Some science……………. The objective of the drilling is to reach the bottom of the glacier. Beneath all temperate glaciers is a subglacial drainage network. The goal of the drilling is to tap this poorly understood hydrologic system. When this drainage network is tapped, water will rise in the borehole to a level indicative of the pressure conditions of this subglacial hydrologic regime. In this case, the goal is to understand where all of the water from Hidden Creek Lake goes, and how it gets there as it begins to drain. Specifically, the objective is to understand the nature of the hydraulic seal that separates the filling lake from the subglacial hydrology, and how the drainage network develops as the lake begins to drain. In drilling to the bed of the glacier near the lake, one of two things will happen. Either the water level in the borehole will rise to the same elevation as the surface of the lake, which will indicate the water is "connected" to the lake. Or, the water will rise to approximately 90% of the thickness of the ice, indicating that the borehole is connected to the hydrologic system that is beneath the main body of the glacier. Ideally, we would like to tap into the latter (the main hydrologic system of the glacier), and see the water level in the borehole transition to lake elevation as the ice is buoyed by the recharging lake. This is pretty complicated, but interesting plumbing.

We just got word from Joe Walder at the lake that the surface of the lake rose today at about half the rate that it did yesterday. The stream gauge on the incoming stream indicates that water is recharging the lake basin at the same rate as it has for the past few days. This means that initial leakage could be starting. Last year when this occurred the break out was only a day away……………… It may be an early outburst flood again this year.

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