Incision of alluvial channels in response to a continuous base level fall: Field characterization, modeling, and validation along the Dead Sea

L. Ben Moshe, I. Haviv, Y. Enzel*, E. Zilberman, A. Matmon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

61 Scopus citations

Abstract

The dramatic lake level drop of the Dead Sea during the twentieth century (∼ 30 m) provides a field-scale experiment in transport-limited incision of gravel-bed channels in response to quasi-continuous base level fall at approximately constant rate. We apply a one-dimensional numerical incision model based on a linear diffusion equation to seven ephemeral channels draining into the Dead Sea. The model inputs include the measured twentieth century lake level curve, annual shoreline location (i.e., annual channel lengthening following the lake level drop), reconstructed longitudinal profiles of each of the channels based on mapped and surveyed terraces, and the current profiles of the active channels. The model parameters included the diffusion coefficient and the upstream-derived sediment flux. Both were first calibrated using a set of longitudinal profiles of known ages and then validated using additional sets of longitudinal profiles. The maximum at-station total incision observed at each of the studied channels was significantly less then the total lake level drop and varied in response to both drainage area and lake bathymetry. The model applied predicted degradation rates and the pattern of degradation with high accuracy. This suggests that sediment flux in the modeled channels is indeed linearly dependent on slope. Further support for this linear dependency is provided by a linear correlation between the diffusion coefficient and the mean annual rain volume over each basin (a proxy for discharge). The model presented could be a valuable tool for planning in rapid base level fall environments where incision may risk infrastructure.

Original languageAmerican English
Pages (from-to)524-536
Number of pages13
JournalGeomorphology
Volume93
Issue number3-4
DOIs
StatePublished - 15 Jan 2008

Bibliographical note

Funding Information:
We are grateful to the following participants of the “Field Methods in Quaternary Research” class (with YE), Y. Bartov, A. Sagy, G. Kuperman, I. Tarshish that created the basis to this study. We thank Dr. B. Z. Begin for fruitful discussions and constructive advice. Several anonymous reviewers helped in improving this manuscript. Initial stages of this work were generously supported by the Dead Sea Research Center (Neve Zohar, Israel). Additional funds were provided by grant 2002-159 of US-Israel Bi-National Science Foundation.

Keywords

  • Base level
  • Channel
  • Dead Sea
  • Diffusion
  • Incision
  • Longitudinal profile
  • Modeling
  • Sediment flux

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