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Knickpoints Along the Upper Indus River, Pakistan: An Exploratory Survey of Geomorphic Processes
Swiss Journal of Geosciences
  • Muhammad F. Ahmed
  • J. David Rogers, Missouri University of Science and Technology
  • Elamin H. Ismail
Abstract

This article summarizes an exploratory study carried out to investigate the significance of various geomorphic features on the formation of observed knickpoints along the upper Indus River in northern Pakistan. These features include bedrock lithology, active faults, sediment flux from tributary channels, and landslide dams which have blocked the main channel. The knickpoints and their related geomorphic parameters (channel profile, concavity, drainage area and normalized steepness index, etc.) were extracted from Advanced Spaceborne Thermal Emission and Reflection (ASTER) Global Digital Elevation Models (GDEMs) with 30 m resolution using ArcGIS, River Tools, and Matlab software. A total of 251 major and minor knickpoints were extracted from the longitudinal profile along a ~ 750 km reach upstream of Tarbela Reservoir. The identified knickpoints and their respective normalized steepness index (ksn values) were compared with bedrock lithology, mapped faults, regional landslide/rockslide inventory, and the locations of historic landslide dams. The analyses revealed that the knickpoints do not correlate with the bedrock lithology except where major unit boundaries coexist with mapped faults, especially in reaches criss-crossed by active thrust faults in the Nanga Parbat Haramosh (NPHM) region. Neither did the river's major confluences exhibit any notable knickpoints, but the correlations between knickpoints, mapped landslides, and historic rockslide avalanche dams accounted for approximately 75% of the observed knickpoints, a surprising finding. These observations suggest that more detailed studies aided by high resolution data should be undertaken to further explore the characteristics of knickpoints triggered by tectonic uplift, local fault offset, bedrock erodibility, and landslide/rockslide dams.

Department(s)
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
  • DEM,
  • Indus River,
  • Knickpoint,
  • Landslide dam,
  • Lithology,
  • Longitudinal profile
Geographic Coverage
Pakistan
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2018 Swiss Geological Society, All rights reserved.
Publication Date
4-1-2018
Citation Information
Muhammad F. Ahmed, J. David Rogers and Elamin H. Ismail. "Knickpoints Along the Upper Indus River, Pakistan: An Exploratory Survey of Geomorphic Processes" Swiss Journal of Geosciences Vol. 111 Iss. 2018-01-02 (2018) p. 191 - 204 ISSN: 1661-8726; 1661-8734
Available at: http://works.bepress.com/j-rogers/88/