Plan-form evolution of drainage basins in response to tectonic changes:
Insights from experimental and numerical landscapes
Abstract
Spatial gradients in rock uplift control the relief and slope
distribution in uplifted terrains. Relief and slopes, in turn, promote
channelization and fluvial incision. Consequently, the geometry of
drainage basins is linked to the spatial pattern of uplift. When the
uplift pattern changes basin geometry is expected to change via
migrating water divides. However, the relations between drainage pattern
and changing uplift patterns remain elusive. The current study
investigates the plan-view evolution of drainage basins and the
reorganization of drainage networks in response to changes in the
spatial pattern of uplift, focusing on basin interactions that produce
globally observed geometrical scaling relations. We combine landscape
evolution experiment and simulations to explore a double-stage scenario:
emergence of a fluvial network under block uplift conditions, followed
by tilting that forces drainage reorganization. We find that the
globally observed basin spacing ratio and Hack’s parameters emerge early
in basin formation and are maintained by differential basin growth. In
response to tilting, main divide migration induces basins’ size changes.
However, basins’ scaling relations are mostly preserved within a narrow
range of values, assisted by incorporation and disconnection of basins
to and from the migrating main divide. Lastly, owing to similarities in
landscape dynamics and response rate to uplift pattern changes between
experiment and simulations, we conclude that the stream power incision
model can represent fluvial erosion processes operating in experimental
settings.