Debris-flow dominated landscapes: morphologic proxies for long-term uplift and erosion rates?

Fluvial channel steepness and hilltop curvature are commonly used as proxies for erosion rate in equilibrium landscapes, but they become less reliable in rocky steeplands dominated by debris flows. We explore an alternative metric—Adf, the drainage area at which valleys transition from slope-invariant to fluvial power-law slope-area scaling—and show that it correlates with erosion rates in several regions. Combining field data with a landform evolution model, we demonstrate that Adf provides insight into where debris-flow processes dominate, and we constrain a physically meaningful debris-flow incision law that offers new insight into how steep landscapes evolve under varying climatic and tectonic conditions.