Crossing divides

Divide mobility and changes in flow network configuration are hot topics these winter days. How mobile are drainage divides, what controls their mobility, which are the involved time scales, and how do shifting divides affect other metrics derived from digital elevation models?

One of the issues addressed by some studies is which metrics are useful to characterize divide movements (Forte and Whipple, 2018, Scherler and Schwanghart, 2019). For example, there are chi maps which allow us to map spatial imbalances in drainage network configuration. However, whether these imbalances actually translate into divide movements, or whether these movements will occur in some distant future remains unclear. Gilbert metrics in turn quantify cross-divide differences in hillslope gradient (or other similar metrics) and thus may provide a more suitable proxy for processes that actually act along or close to divides. To this end, it may often be useful to look at both types…