Satellite tv for pc imagery reveals that North Korea and China have reopened the Supung Dam’s floodgates on the Yalu River, releasing water as soon as extra. This motion seems to be a safety measure to manage the reservoir’s water degree, as elevated movement from the river’s higher reaches threatens to exceed the Supung Reservoir’s most capability.
I analyzed flood injury within the Yalu River basin, specializing in the Supung Dam and Sinuiju space, utilizing Artificial Aperture Radar (SAR) photographs from the European Area Company’s Sentinel-1 satellite tv for pc. These radar sensors can observe Earth in all climate situations, providing a definite benefit over optical satellite tv for pc photographs which might be affected by darkness, clouds, or time of day. By evaluating SAR photographs earlier than and after heavy rains, I examined the flood scenario utilizing publicly out there information. This evaluation showcases the advantages, limitations, and distinctive traits of SAR imagery in assessing environmental adjustments and catastrophe impacts.
After heavy rains on July 28 and 29, satellite tv for pc photographs captured a number of cases of the 420-meter-long floodgates being totally opened for a couple of week till Aug. 4. On account of cloudy and poor climate situations, the scenario on the Supung Dam was not observable till Aug. 7, when satellite tv for pc imagery indicated that the water launch had halted. On Aug. 15, the dam was discovered to have partially launched water by opening a few of its floodgates.
The partial launch of water from the Supung Reservoir seemingly goals to manage its degree because the Yalu River swells with elevated movement from upstream North Korean provinces. In adjoining Liaoning province, flooding has submerged a small dam, making a 6-kilometer diversion channel. This waterway fashioned when Supung Reservoir overflow adopted a low-lying valley, bypassing the Supung Dam and rejoining the Yalu River downstream. The speedy movement by this new channel might have broken or destroyed Chinese language villages and amenities beforehand positioned within the valley. As a result of flooding, the small Chinese language dam is presently not seen on satellite tv for pc imagery.
I examined the scenario across the Supung Dam earlier than and after the heavy rains utilizing SAR imagery. From the radar satellite tv for pc photographs, I can verify that the width of the Yalu River has elevated because the water degree has risen. The SAR photographs additionally present that a part of the tail-shaped land on the riverbank has been submerged the place the water flowing down alongside Gugok Stream from the inside of North Pyongan province meets the Yalu River.
The above SAR photographs present the Yalu River basin round Sinuiju earlier than and after heavy rains. Radar satellite tv for pc photographs are proven in black and white, with areas that replicate much less to the satellite tv for pc sensor, such because the Yalu River water or Sinuiju airport, showing in black. On the island of Wihwa, which was break up into a number of elements by the heavy rains, the muddy streams created by the speedy currents are clearly seen as skinny black traces. I’ve indicated the place the place Kim Jong Un visited by prepare on July 28.
SAR photographs are produced by satellites firing radar waves on the floor and recording the energy of the electromagnetic beams mirrored from the floor and detected by the satellite tv for pc’s sensors. The information could be downloaded freed from cost from the European Area Company’s (ESA) net browser (Copernicus Browser) after registration. The imaging cycle is comparatively lengthy at 12-day intervals. SAR satellite tv for pc photographs present floor options in black and white and have the benefit that they are often acquired no matter climate situations, even at evening when it’s cloudy or overcast. Optical satellite tv for pc photographs, that are extensively used, can characterize pure colors as we see them with our eyes, however are depending on daylight and affected by climate situations. SAR information characterize the tough and clean states of the floor, so some professional data is required to know the satellite tv for pc photographs. Tough surfaces seem brilliant on account of excessive reflectivity, whereas clean surfaces corresponding to lake water seem darkish on account of low reflectivity. As proven within the picture above, the Supung Reservoir and Yalu River water seem darkish on account of low floor reflectivity.
The historical past of SAR satellites dates again to the Seventies, making it so long as that of optical satellites. SAR information has been much less utilized as a result of it requires specialised methods to know and course of floor situations and has some difficult points. Consequently, SAR information has been utilized in a extra restricted manner, typically as an adjunct to optical imagery relatively than independently. Analysts who interpret and analyze satellite tv for pc imagery usually keep away from SAR photographs due to the restricted data they produce and their inconveniences. Nevertheless, the photographs are undoubtedly an vital asset of Earth statement satellites.
South Korea’s army efficiently launched and orbited the SAR sensor-equipped Reconnaissance Satellite tv for pc 2 on April 8 this yr. The army plans to launch three extra SAR satellites sooner or later, with the objective of working a complete of 4 SAR reconnaissance satellites. That is anticipated to vastly improve the nation’s surveillance and reconnaissance capabilities over North Korea and contribute considerably to the event of satellite-related industries in South Korea in an period of rising house competitors within the worldwide area.
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