Channels incision determines the “local base level” and the nature of valley hillslopes. Local base can also describe the surface created by connecting channel long profiles. Here, we’ll just describe two metrics for a single basin and its corresponding channel and ridgeline long profiles:Hillslope relief is the vertical distance between the ridgeline of a watershed and a sloping line drawing through channel heads of low-order streams (usually 1st order) in the watershed.
Channel relief is the vertical distance between the same sloping line and the elevation of the trunk channel. There is flexibility in where along the trunk channel the measurements can be taken, however, both should be collected at the same location.
Clark et al. (2005b) GSA Today 15
Whipple and Tucker (1999) Journal of Geophysical Research 104
Burbank and Anderson (2012, p. 245, Fig. 8.1)