The Arctic’s Largest Delta
Editor’s note: This video explores the diverse landscapes and waterscapes of the Lena River Delta. The image was acquired on July 13, 2021, with the Operational Land Imager (OLI) on Landsat 8. Norman Kuring of NASA’s Ocean Biology group applied color-filtering techniques to draw out the fine details in the water, but the features are real. The following text is a transcript of the video.
From the Baikal Mountains in south-central Russia, the Lena River flows north for thousands of miles.
As the river nears the Laptev Sea, it branches out across broad, flat tundra.
This is the Lena River Delta.
It spans nearly 30,000 square kilometers—about the same size as the U.S. state of Maryland.
Located in northeastern Siberia, it is the Arctic’s largest delta.
In this image, water is colored brown in part by organic matter—leaves, soils, plant debris—dissolved in the water.
Suspended sediments in the river water also add to the palette.
The Landsat 8 satellite acquired these images in July 2021.
Spring floods, caused by the rapid melting of snow over permafrost, had recently come and gone.
Water pooled in depressions where permafrost had thawed.
About 30,000 lakes dot this tundra landscape.
Around the streams and lakes, the landscape is covered with moss, grass, sedge, and shrubs.
The region includes important habitat and nesting sites for migratory birds.
Mudflats and sandy areas are visible along the riverbanks and coastlines.
Many of these areas are rapidly eroding and taking permafrost along with it.
Some of the largest losses have occurred along a cliff on Sobo-Sise Island.
Erosion releases substantial amounts of carbon and nitrogen to the water.
This could affect the food web in Arctic waters and release greenhouse gases to the atmosphere.
At the Laptev Sea, the colors trace the freshwater and highlight otherwise invisible currents and eddies.
Sea ice in the Laptev Sea melted away earlier than usual in summer 2021.
Just a few patches remained at the time of this image.
Starting around October, streams and tributaries will begin to freeze again, and erosion will slow.
The delta will stay locked in ice until the cycle of thawing and flooding resumes in spring.
NASA image by Norman Kuring/NASA's Ocean Color Web, using Landsat data from the U.S. Geological Survey. Video by Kathryn Hansen.