Preprints
https://doi.org/10.5194/esurf-2021-11
https://doi.org/10.5194/esurf-2021-11

  24 Feb 2021

24 Feb 2021

Review status: a revised version of this preprint is currently under review for the journal ESurf.

The rate and extent of windgap migration regulated by tributary confluences and avulsions

Eitan Shelef1 and Liran Goren2 Eitan Shelef and Liran Goren
  • 1Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA, 15217
  • 2Department of Earth and Environmental Sciences, Ben-Gurion University of the Negev, Israel, 84105

Abstract. The location of drainage divides sets the distribution of discharge, erosion, and sediment flux between neighboring basins, and may shift through time in response to changing tectonic and climatic conditions. Major divides commonly coincide with ridgelines, where the drainage area is small and increases gradually downstream. In such settings, divide migration is attributed to slope imbalance across the divide that induces erosion rate gradients. However, in tectonically affected region, low-relief divides, windgaps, abound in elongated valleys, whose drainage area distribution is set by the topology of large, potentially avulsing side-tributaries. In this geometry, distinct dynamics and rate of along-valley windgap migration is expected, but this process remains largely unexplored. Inspired by field observations, we investigate along-valley windgap migration by simulating the evolution of synthetic and natural landscapes, and show that confluences with large side tributaries influence migration rate and extent. Such confluences facilitate stable windgap locations that deviate from intuitive expectations based on symmetry considerations. Avulsions of side tributaries can perturb stable windgap positions and avulsion frequency governs the velocity of windgap migration. Overall, our results suggest that tributaries and their avulsions may play a critical role in setting the rate and extent of windgap migration along valleys and thus the time scale of landscape adjustment to tectonic or climatic changes across some of the most tectonically affected regions of Earth, where windgaps are common.

Eitan Shelef and Liran Goren

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esurf-2021-11', Helen Beeson, 25 Mar 2021
    • AC1: 'Reply on RC1', Eitan Shelef, 07 May 2021
  • RC2: 'Comment on esurf-2021-11', Fiona Clubb, 01 Apr 2021
    • AC2: 'Reply on RC2', Eitan Shelef, 07 May 2021

Eitan Shelef and Liran Goren

Eitan Shelef and Liran Goren

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Short summary
Drainage basins are bounded by water divides (divides) that define their shape and extent. Divides commonly coincide with high ridges, but in places that experienced much tectonic deformation, divides sometimes cross elongated valleys. Inspired by field observations and using simulations of landscape evolution, we study how side channels that drain to elongated valleys induce pulses of divide migration, affecting the distribution of water and erosion products across mountain ranges.