To what extent have humans had a positive impact along the river
Severn?

please i really need it.

river ecosystems result from human alterations both outside river corridors, such as timber harvesting and urbanization, and within river corridors, including flow regulation, river engineering, and removal of large-wood debris and beaver dams.

Explanation:

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the only other powers were germany russia and uk and they were too busy fighting each other wearing each other down   that the us was becoming strong and they were becoming weaker