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Friday, Oct 07, 2022

NASA releases new pictures that reveal scale of decline in Lake Mead’s water levels

One of the largest reservoirs in the US, Lake Mead straddles Arizona and Nevada and is one of the primary sources of water for California, Arizona and Nevada.

NASA has released images that show the sharp decline in water levels in America's Lake Mead over the past 22 years. (Photos via NASA)

NASA has released images that show the sharp decline in water levels in America’s Lake Mead over the past 22 years. The report said that the water levels stand at a little over one-quarter of the total capacity, the lowest levels recorded since April 1937.

One of the largest reservoirs in the US, Lake Mead straddles Arizona and Nevada and is one of the primary sources of water for California, Arizona and Nevada. Its lowering water levels have triggered concerns of water shortage and sub-par snowpack levels in the winters.

The natural-coloured images that highlight the stark contrast in the depreciating water levels were taken from July 6, 2000, and July 3, 2022, respectively. The earlier image was acquired by Landsat 7, the most accurately calibrated Earth-observing satellite back then, while the latter was captured by the 2013- launched Landsat 8.

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An additional detailed image (middle) by Landsat 8 has been provided for bridging the gap between the two which dates back to July 8, 2021.

The images from 2021 and 2022 both lay emphasis on the broadening band of faded-coloured fringes which represent the mineralised areas along the lakeshore from where the water has dried up ever since the reservoir has been up to the brim. These pale outlines are what has been scientifically referred to as the “bathtub effect”.

According to NASA’s official website, this phenomenon is observed when the canyon walls which were otherwise inundated, get exposed to open air once the water level drops. The bare sandstone reacts with the calcium carbonate and other mineral salts in the water, thus settling on the surface to give off this white mark. The only time this effect is not apparent is when the water levels of the lake are maximum.

Local precipitation and groundwater contribute to up to 10% of water levels of Lake Mead while the majority of it pertains to the snowmelt in the Rocky Mountains via the Colorado River watershed that spans t through Lake Powell, Glen Canyon, and the Grand Canyon. , Managed by USBR, the Colorado River basin is revered as life support for providing electric power and water to approximately 40 million people from key cities of San Diego, Las Vegas, Phoenix, Los Angeles and about 4 to 5 million acre areas of farmland in the Southwest.

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Additionally, Lake Mead is an indispensable national recreation area that is a huge rage amongst boating enthusiasts. But with time, five out of six boating ramps/launches have now gone defunct according to the National Park Service, given the “declining water levels due to climate change and 20 years of ongoing drought” that continues to reshape the park’s shorelines.

First published on: 23-07-2022 at 02:46:15 pm
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