Decoding the role of tectonics, incision and lithology on drainage divide migration in the Mt. Alpi region, southern Apennines, Italy

The proclivity of river networks to progressively carve mountain surfaces and preserve markers of landscape adjustments has made analyses of fluvial systems fundamental for understanding the topographic development of orogens. However, the transient nature of uplift and erosion has posed a challenge for inferring the roles that tectonics and/or climate have played on generating topographic relief. The Mt. Alpi region in the southern Apennines has a heterogeneous distribution of elevated topography, erosionally-resistant lithology and uplift, making the area optimal for conducting topographic and river analyses to better understand the landscape development of a transient orogen. Stream length-gradient, normalized channel steepness, stream convexity and first-order channel gradient indices from 10 m digital elevation data from the region exhibit stream profile inconsistencies along the current drainage divide and a dominance of high values subparallel but inboard of the primary chain axis irrespective of known transient landscape factors, suggesting that the current river network may be in a state of transition. The location of these stream profile anomalies both near the modern drainage divide and subparallel to an isolated swath of high topography away from catchment boundaries is thought to be the topographic expression of an imminent drainage divide migration driven primarily by the ~ northeast-vergent extension of the western chain axis.