Satellites capture massive drainage of proglacial lake in remote Patagonia – SpaceRef

Only satellites were watching as the world’s fourth-largest proglacial lake suddenly drained in 2020. Researchers from Hokkaido University have now uncovered the event and analyzed the cause – the collapse of a sediment bulge at the lake’s outlet.

Proglacial lakes form when meltwater from retreating glaciers is trapped by ice or a moraine left behind by the same or another glacier. A warming climate is contributing to the recent global increase in the number and volume of these lakes, and they themselves are also helping glaciers melt even faster. However, these lakes can drain very quickly if the dams that contain them fail for any of a variety of reasons. Such a catastrophic event not only poses a direct safety risk to humans, but also affects downstream ecosystems due to the sudden inflow of a large amount of fresh water. It is therefore important to monitor proglacial lakes and study their interactions with their environment. Unfortunately, this is difficult due to their often remote location.

Hokkaido University glaciologist Shin Sugiyama and PhD student Shuntaro Hata were studying glacial fluctuations in Chilean Patagonia using satellite imagery when they found that the proglacial lake Lago Greve had shrunk significantly in the short period between April and July 2020. In their publication of their findings in the journal Communications Earth & Environment, they add further analysis of the available data, which confirms that the lake’s water level has dropped 18 meters, resulting in a loss of 3.7 cubic kilometers (or gigatons) of water corresponds to the largest loss of this type observed by a satellite to date. This enormous loss of water even measurably altered the Earth’s gravitational field, as recorded by GRACE satellites, although the quantitative data from these satellites does not match the actual amount of water released. Finally, careful analysis of satellite imagery and topographical data from before and after the event allowed the conclusion that the cause of the release was likely the intrusion of a sediment bulge near the lake’s outlet.

This study opens up many interesting aspects. On the one hand, it points the way for future research on glacier dynamics. Sugiyama explains, “These results provide detailed information on large-scale glacial lake outbursts, which occur very rarely, and are important for understanding glacial lake outburst-related disasters.” It also highlights the possibility and current limitations of using GRACE satellite data observation of such events. The researchers suggest: “The importance of GRACE measurements in studying such events would be increased if the calculation of gravitational field values ​​for localized events were adjusted.” better understand the lakes they form, because “the observed changes in water level of glacial lakes can be used to predict changes in glacial inflow into the lakes.”

Abrupt drainage of Lago Greve, a large proglacial lake in Chilean Patagonia, observed by satellite in 2020, Communications Earth And Environment