Spanning six countries, the Mekong River is an important lifeline to nearly 60 million people across Southeast Asia. The fast-flowing river is a source of fish and helps transport sediments across the region, improving soil fertility for farmers. The sediments also give the river its signature muddy brown appearance. But for the past few months, the sediment loads have dropped and the Lower Mekong River has turned an unusual aquamarine color.
The color change was first reported in northern Thailand in November 2019, and has since spread along the Lower Mekong. The images above show the river near the town of Huay Xai in Laos. The left image shows the river under normal, sediment-laden conditions on January 27, 2015, compared to conditions on January 25, 2020. Both images were acquired by the Operational Land Imager (OLI) on Landsat 8.
The Mekong River Commission (MRC) stated that the water change is due to extremely shallow and slow-moving river flows. In turn, fine sediments have dropped out and created clearer water conditions.
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Image via NASA Earth Observatory