downward vs upslope

downward

adj
  • Moving, sloping or oriented downward. 

  • Located at a lower level. 

adv
  • At a lower level. 

  • Southward. 

  • Toward a lower level, whether in physical space, in a hierarchy, or in amount or value. 

upslope

adj
  • in a direction up a slope 

adv
  • up a slope 

noun
  • an upward slope 

How often have the words downward and upslope occurred in a corpus of books? (source: Google Ngram Viewer )