Understanding the response of Alaska's ecosystems to a changing climate to support resource managers and sustainable communities

 

a group of people poses for a photo

Attendees from the 2019 CASC Network Meeting in Tuscon.

From the cool boreal forest of Alaska to the hot desert of Arizona– representatives from the CASC network traveled to Tucson, Arizona for the 2019 CASC Network Meeting last week.

people at a table

Ryan Toohey works with participants on an exercise connecting climate impacts across the landscape.

AK CASC’s Ryan Toohey, Jeremy Littell, and Malinda Chase will travel to communities participating in the Looking Forward, Looking Back workshop.

Update 07/27/2018

We were up in the basin on Monday and Tuesday to survey points, fly the drone and recover some of our instruments. Unfortunately, the two backup gages are covered by several meters of ice. We still hope to get them back by the end of the season. There is a lot of ice perched high up in the basin, probably related to the disintegration of the floating tongue, which produced a lot of freely moving ice.

Photo of glacial water in Suicide Basin field site.

Photo from field site visit on July 17th, 2018.

Site visit 07/17/2018

We visited Suicide Basin earlier tonight (4:00 until 7:30 pm). The water flow over the dam diminished during that time while the water level in the lake started dropping noticeably. The drop is also visible in the timelapse feature tracking.

Photo of the water level of Suicide Basin from July 16th, 2018 site visit.

Photo from field site visit on July 16th, 2018.

Site flyover 07/16/2018

Suicide Basin started spilling over this morning and the water elevation appears to have reached temporary steady state between 3:00 and 6:00 pm today.

We flew over the site this afternoon. Some of my photos below. Water level according to our imagery was at ~442 m, about 0.5 m higher than the lowest point in the dam.

orthoimage including elevation contours of Suicide Basin

Fig. 1. Orthoimage from 07/12/2018 including elevation contours. Lake level at 5:50 pm was approximately 438.5 m The lowest point of the dam has an elevation of 441.5 m.

Water level at 5:50 pm: ~438.5 m

Water level increase 3:30 pm – 5:50 pm: 9 cm (equivalent to 0.93 m / day)

Lowest point of dam: ~ 441.5 m

As of last night, there was a 3 m difference between the water level elevation and the elevation of the lowest point of the dam (Figures 1, 2). At the current rate of water level increase, the lake would start spilling over between Sunday evening and Monday morning. While the water level increase slowed down last night (cold, no rain), warm temperatures today and rain on Saturday/Sunday may reverse this trend again.

photo of the water level of Suicide Basin

Figure one from field site visit on July 10th, 2018.

Current situation

As of 6:00 pm today, the water level in Suicide Basin was still rising. According to our estimates, current water volumes in Suicide Basin are in the ballpark of the 2016 flood. Today at noon, the median of our Monte Carlo simulations yielded 0.0325 km3, while the volume of the 2016 flood was approximately 0.035 km3.

ice from a glacier in a basin

Photo from site visit on July 24th, 2019

We completed our post-drainage site visit on 24 July, roughly one week after completion of the lake drainage. We surveyed the basin with the drone, measured ice melt at the melt wires, and also installed a new melt wire up on Suicide Glacier. This new melt wire at 950 m above sea level complements the temperature sensor deployed next to Suicide Glacier and allows for a melt model calibration across the entire Suicide Basin watershed.    

View across the overflowing portion of the lake. The water runs along the glacier boundary towards Mendenhall Lake visible in the far distance.

View across the overflowing portion of the lake. The water runs along the glacier boundary towards Mendenhall Lake visible in the far distance. Photo by Christian Kienholz.

As smoke from distant wildfires clouds the skies above Southeast Alaska, Juneau residents have a much closer hazard on their minds. Warm weather sped up water collection in Suicide Basin, a glacier-dammed lake adjoining Mendenhall Glacier that has generated outburst floods regularly over the last decade. On Sunday, July 7th, the basin water level reached a point where it began to overtop the Mendenhall Glacier ice dam, flowing along the side of the glacier towards Mendenhall Lake. Almost one week later, on July 13th, the basin began draining beneath the glacier.

ice from a glacier in a basin

Photo from site visit on July 8th, 2019

The lake started overtopping the dam on Sunday 7 July in the morning and reached its maximum level shortly thereafter. The water level in the basin has been slowly dropping since due to erosion of the overflowing water at the ice dam. Subglacial drainage has not begun as of Monday afternoon. In 2018, the lake started draining subglacially within ~24 hours of dam overtopping. The timeline will be different this season, however, accurate predictions are not possible. We suspect subglacial drainage will happen within the next few days.

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