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October 9, 2024 - Sediment Fills Tennessee River after Hurricane Helene
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More than a week after Hurricane Helene dumped torrential rain across southern Appalachia, the rivers and lakes of East Tennessee were laden with post-hurricane sediment and debris. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this true-color image of the muddy rivers of the region on October 3, 2024.
The city of Knoxville, Tennessee can be seen as a spider-web-like grouping of gray pixels at the headwaters of the muddy Tennessee River, just west of center in this image. The French Broad and the Holston River converge to create the Tennessee River just north of the city. Asheville, North Carolina, another sprawling group of gray pixels, can be seen in the lower right corner (southeast).
The prominent reverse-s-shaped feature on the eastern side of the main line of rivers is Douglas Lake. Located in East Tennessee and spanning about 28,000 acres, it was formed when the Tennessee Valley Authority (TVA) build a dam on the French Broad River in the 1940s. The twisting, dark-colored French Broad can be seen to the east of Douglas Lake and pouring into it. The French Broad begins near the continental divide in North Carolina.
The Pigeon River and Nolichucky River also feed into to Douglas Lake; they both also rise in North Carolina. The French Broad, Nolichucky, and Pigeon Rivers all were flooded by the most extreme rainfall amounts from Hurricane Helene, and all carried debris from the storm into Douglas Lake. The Holston River, in contrast, begins in the foothills of the Smoky Mountains in East Tennessee. Although it also flooded, it was not impacted as much as the other three rivers. The Holston River runs roughly parallel and northwest of the French Broad and is not easily seen in this image. The Tennessee River, from Knoxville southward, appears not only sediment-laden but also swollen from high water along its entire course.
Hurricane Helene made landfall in the Big Bend region of Florida late on September 26, and quickly drove northward to reach Southern Appalachia. East Tennessee and western North Carolina were absolutely drenched with torrential rain from September 26-27, and lighter rain continued to fall on September 28. This followed a “predecessor event,” which had brought rain to the region for several days before the storm itself made impact. The predecessor rain filled rivers and streams and soaked into the ground, setting the stage for utter devastation when Helene dropped its load.
By September 28, 30 inches of rain from Helene had been recorded at Busick, North Carolina, a small town near Mount Mitchell, according to local news reports. Busick is located northeast of Asheville. The heavy rain, estimated at 15-30 inches across parts of eastern North Carolina, triggered flash flooding, landslides, power outages, and destruction of homes, businesses, and water supplies. It also caused multiple deaths across both states.
With the heaviest rain pouring across the Smoky Mountains near Asheville, the Pigeon, French Broad, and Nolichucky Rivers all flooded to record or near-record levels. Knox News put it this way, “The rivers ran uncontrolled and unmoored from their banks for miles, carrying away houses, roads, and bridges before converging and flowing into Douglas Lake”. Indeed, Douglas Lake has become a resting place for miles of debris washed into it from the storm. On October 4, local media reported that the TVA was installing a one-mile-long boom into the middle of Douglas Lake to help contain the debris within the lake. Removing that debris is a separate operation and will take place over the coming months.
Image Facts
Satellite:
Terra
Date Acquired: 10/5/2024
Resolutions:
1km (47.8 KB), 500m (125.8 KB), 250m (215 KB)
Bands Used: 1,4,3
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
More than a week after Hurricane Helene dumped torrential rain across southern Appalachia, the rivers and lakes of East Tennessee were laden with post-hurricane sediment and debris. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this true-color image of the muddy rivers of the region on October 3, 2024.
The city of Knoxville, Tennessee can be seen as a spider-web-like grouping of gray pixels at the headwaters of the muddy Tennessee River, just west of center in this image. The French Broad and the Holston River converge to create the Tennessee River just north of the city. Asheville, North Carolina, another sprawling group of gray pixels, can be seen in the lower right corner (southeast). The prominent reverse-s-shaped feature on the eastern side of the main line of rivers is Douglas Lake. Located in East Tennessee and spanning about 28,000 acres, it was formed when the Tennessee Valley Authority (TVA) build a dam on the French Broad River in the 1940s. The twisting, dark-colored French Broad can be seen to the east of Douglas Lake and pouring into it. The French Broad begins near the continental divide in North Carolina.
The Pigeon River and Nolichucky River also feed into to Douglas Lake; they both also rise in North Carolina. The French Broad, Nolichucky, and Pigeon Rivers all were flooded by the most extreme rainfall amounts from Hurricane Helene, and all carried debris from the storm into Douglas Lake. The Holston River, in contrast, begins in the foothills of the Smoky Mountains in East Tennessee. Although it also flooded, it was not impacted as much as the other three rivers. The Holston River runs roughly parallel and northwest of the French Broad and is not easily seen in this image. The Tennessee River, from Knoxville southward, appears not only sediment-laden but also swollen from high water along its entire course.
Hurricane Helene made landfall in the Big Bend region of Florida late on September 26, and quickly drove northward to reach Southern Appalachia. East Tennessee and western North Carolina were absolutely drenched with torrential rain from September 26-27, and lighter rain continued to fall on September 28. This followed a “predecessor event,” which had brought rain to the region for several days before the storm itself made impact. The predecessor rain filled rivers and streams and soaked into the ground, setting the stage for utter devastation when Helene dropped its load.
By September 28, 30 inches of rain from Helene had been recorded at Busick, North Carolina, a small town near Mount Mitchell, according to local news reports. Busick is located northeast of Asheville. The heavy rain, estimated at 15-30 inches across parts of eastern North Carolina, triggered flash flooding, landslides, power outages, and destruction of homes, businesses, and water supplies. It also caused multiple deaths across both states.
With the heaviest rain pouring across the Smoky Mountains near Asheville, the Pigeon, French Broad, and Nolichucky Rivers all flooded to record or near-record levels. Knox News put it this way, “The rivers ran uncontrolled and unmoored from their banks for miles, carrying away houses, roads, and bridges before converging and flowing into Douglas Lake”. Indeed, Douglas Lake has become a resting place for miles of debris washed into it from the storm. On October 4, local media reported that the TVA was installing a one-mile-long boom into the middle of Douglas Lake to help contain the debris within the lake. Removing that debris is a separate operation and will take place over the coming months.
Image Facts
Satellite:
Terra
Date Acquired: 10/5/2024
Resolutions:
1km (47.8 KB), 500m (125.8 KB), 250m (215 KB)
Bands Used: 1,4,3
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
