Science & Technology

Yukon-Kuskokswim in Colorful Transition: Remarkable Example of How Water and Ice Can Shape the Land

Could 29, 2021

One of the world’s largest deltas stands as a outstanding instance of how water and ice can form the land.

The Yukon-Kuskokswim Delta is one of the world’s largest deltas, and it stands as a outstanding instance of how water and ice can form the land. These pictures present the delta’s northern lobe, the place the Yukon River spills into the Bering Sea alongside the west coast of Alaska.

“The Yukon Delta is an exceptionally vivid panorama, whether or not seen from the floor, from the air, or from low-Earth orbit,” stated Gerald Frost, a scientist at ABR, Inc.—Environmental Analysis and Companies in Fairbanks, Alaska. The vivid panorama is captured in these pictures acquired with the Operational Land Imager (OLI) on Landsat 8 on Could 29, 2021. The photographs are composites, mixing natural-color imagery of water with a false-color picture of the land.

Whereas the picture could possibly be thought of a piece of artwork, there are some helpful elements to taking a look at the land this fashion. For instance, you possibly can simply distinguish areas of reside vegetation (inexperienced) from land that’s naked or incorporates lifeless vegetation (mild brown) from the community of sediment-rich rivers and ponded flood water (darkish brown). A sprinkling of thermokarst lakes are additionally half of the scene.

Could 29, 2021

On the whole, the inexperienced areas throughout the delta are tall willow shrublands. They’re particularly obvious on both facet of the river channels in the detailed picture above. The sunshine-brown areas are primarily moist sedge meadows; they seem brown as a result of a lot of it’s the lifeless stays of final 12 months’s development. Away from the delta (proper facet of the picture) the vegetation is shrub-tussock tundra.

“To me, one of the fascinating issues about the delta is that it’s a extremely transitional space, with some parts of Arctic tundra and some of boreal forest,” Frost stated.

The delta additionally transitions with the seasons. At the time of this picture, the signature of spring flooding is written throughout the delta. Melting snow and ice trigger the rivers to spill over their banks and by late Could, many of the marshes are crammed with floodwater, which seems as dark-brown ponds.

In keeping with Lawrence Vulis, a graduate scholar at the College of California, Irvine, the delta would have appeared rather more inundated instantly following the melting of snow and ice just a few weeks previous to this picture. Stream gauges and satellite tv for pc pictures counsel that the bulk of the flooding had already subsided. Nonetheless, the flooding was current sufficient that the lots of ponding remained on Could 29. As summer season advances, the floodwater will proceed to recede and the wetlands will proceed to inexperienced up with vegetation.

Additionally discover the colourful water the place the delta meets the Bering Sea. This can be a product of glacial runoff far upstream, which carries a big quantity of sediment towards the coast. This sediment can also be instrumental to the formation of tall “levees” on the sides of the channels, deposited there when floodwaters spill over their banks. These “levees” assist stands of tall willows—necessary habitat for moose.

“Curiously, tall shrubs have expanded so much on the delta in current many years, and the moose have adopted,” Frost stated. “At this time, the delta has one of the highest moose densities in the state of Alaska.”

The delta didn’t at all times look this fashion. Research have proven that the fashionable Yukon Delta is just some thousand years previous. It’s younger age “is unbelievable to consider,” Vulis stated. “We’re used to interested by comparatively historical landscapes, however fashionable river deltas have solely fashioned in the final 10,000 to eight,000 years since international sea stage has stabilized.”

The delta may fairly probably look completely different in the future. “The Yukon and different Arctic deltas are considered notably weak to local weather change,” Vulis famous, “because of the roles of permafrost and ice in shaping these deltas.”

NASA Earth Observatory pictures by Joshua Stevens, utilizing Landsat knowledge from the U.S. Geological Survey.

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