The probabilistic nature of the relation between water-input rate and outburst-flood occurrence suggests that the connections between englacial conduits, basal cavities and main meltwater channels may vary temporally. On the basis of these results, we suggest that outburst floods are triggered when rapid input of water to the glacier bed causes transient increase in water pressure, thereby destabilizing the linked-cavity system. of the Pacific Northwest, Canada, and Alaska including the Tlingit, Haida.
Statistical analysis shows that outburst floods usually occur during periods of atypically hot or rainy weather in summer or early autumn, and that the probability of an outburst increases with temperature (a proxy measure of ablation rate) or rainfall rate. Glaciers form when snowfall exceeds melt and the snow compacts into ice. The volume of stored water discharged during a typical outburst flood would form a layer several tens of millimeters thick over the bed of the entire glacier, though it is more likely that large linked cavities account for most of the storage.
Outburst floods from South Tahoma Glacier form by release of subglacially stored water. These heatwaves can lead to mass die-offs of fish in streams that become too warm for them. However, little or none of this sediment has yet passed out of the Tahoma Creek drainage basin. As climate change continues to worsen, heatwaves like one that killed hundreds of people as it rolled across the Pacific Northwest last summer have become more common and more extreme. The average denudation rate in the upper part of the Tahoma Creek drainage basin in the same period has been extraordinarily high: more than 20 millimeters per year, a value exceeded only rarely in basins affected by debris flows. Debris flows in Tahoma Creek valley have transported downstream about 10**7 m**3 of sediment since 1967, causing substantial aggradation and damage to roads and facilities in Mount Rainier National Park. It is believed that the water filters the longwave radiation sufficiently for the ice worms to hang out there during bright periods. Debris flows have been especially important agents of geomorphic change along Tahoma Creek, which drains South Tahoma Glacier. Ice worms are often sighted in the glacier meltwater pools, slush, and streams found in or on top of glacier ice, even during the day. This stagnant ice is a relic of advanced glacier positions achieved during the mid-nineteenth century Little Ice Age maximum and the readvance of the 1960's and 1970's. Nearly all of these flows began as glacial outburst floods, then transformed to debris flows by incorporating large masses of sediment in channel reaches where streams have incised proglacial sediments and stagnant glacier ice. 'Its happening,' scientist Scott Hotaling told a reporter for OPB as he gestured across Paradise Glacier high up on Mount Rainier in Washington. Debris flows have caused rapid geomorphic change in several glacierized drainages on Mount Rainier, Washington.
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