Which mechanism accelerates stream incision when base level drops through an alluvial terrace?

💡 Explanation

When the base level of a stream drops, knicking occurs because the altered slope locally increases stream power, causing focused erosion and headward migration as the steeper gradient propagates upstream. Therefore knicking action accelerates incision, rather than aggradation, avulsion, or glacial outburst which involve different geomorphic processes occurring at different scales and under different controls.

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