Definition of downcut in US English:

downcut

verb

[no object]Geology
  • (of a river) erode downward through its bed.

    • ‘After two winters, Canon Creek has downcut approximately 3 feet and has a deeper, more defined channel.’
    • ‘Once a channel starts to downcut, it usually does not stop until it has caused a lot more erosion.’

Pronunciation

downcut

/ˈdounˌkət/