Sunday, 19 May 2019

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66,000 hectares of land lost to Padma since 1967: NASA

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Health Desk--15 Sep’18: Bangladesh has lost over 66,000 hectares (256 square miles) of land—roughly the area of Chicago, one of the biggest cities in the US—to Padma River erosion since 1967.

That is according to an August 2018 report published by the NASA Earth Observatory, the arm of the US space agency that is focused on the planet we live in, UNB reported.

The extreme erosion patterns of the Padma are known to have two main causes. First, it is a natural, free-flowing river with little bank protection, other than some occasional sandbags to protect buildings. Second, the bank sits on a large sand bed that can be eroded quickly.

The NASA report, "The Shape of Erosion", compares natural-color satellite images showing the changes to the shape and width of the Padma since 1988.

Each "twist and zigzag" is said to tell a different geologic story about the river. The images were acquired by NASA's Landsat satellites: the Thematic Mapper on Landsat 5, the Enhanced Thematic Mapper Plus on Landsat 7, and the Operational Land Imager on Landsat 8.

Scientists, however, measure erosion on the Padma River by noting differences in its width, depth, shape, and overall appearance on satellite images.