Geomorphic and lithologic control on bedrock channels in drainage basins of the Western Arabian Peninsula
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ORIGINAL PAPER
Geomorphic and lithologic control on bedrock channels in drainage basins of the Western Arabian Peninsula Ali P. Yunus 1
Received: 22 May 2015 / Accepted: 18 September 2015 # Saudi Society for Geosciences 2016
Abstract Hypsometric curves, their integrals and channel profiles have long been used as effective indicators of stages in topographic evolution. This work presents the geomorphic and lithologic aspects of the drainage basins in the Western Arabian Peninsula by analysing basin hypsometry and channel longitudinal profile steepness and concavity indices in order to understand the erosion regimes. A total of 36 drainage basins in the region were analysed in a geographic information system (GIS) environment with a 30-m ASTER Global Digital Elevation Model. Hypsometric curves display shapes resembling from S-shaped to concave curves. Hypsometric integral (HI) shows generally low values in the study area and varies between 0.13 and 0.5, with a mean of 0.27. From the main set of 36 drainage basins defined, three sets of subbasins were derived for each Strahler order ranging from 4 to 6. Their HI varied between 0.08 and 0.66 with an average HI of 0.33. Then, the HI for each basin order was plotted against the distance from the central location of each basin from south to north. Results reveal that basin hypsometry is independent of spatial variation and spatial scale. Also no clear relations Highlights (1) Comprehensive geomorphological research on the steep drainage basins in the arid terrain. (2) Main channel steepness and concavity indices were derived for 36 basins. (3) Analysis of HI and longitudinal profile throws light on the effect of lithology on erosion. Electronic supplementary material The online version of this article (doi:10.1007/s12517-015-2179-7) contains supplementary material, which is available to authorized users. * Ali P. Yunus [email protected] 1
Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha 5-1-5, 277-8563 Tokyo, Japan
were found between HI and basin area and shape. Further, HI and hypsometric curves were analysed in terms of lithological control on landforms. Results indicate that basin hypsometry is sensitive to lithological variation in the study area. At the largest scale, the HI values can be divided into two populations. More evenly distributed erosion in crystalline rocks and relatively uneven erosion in volcanic rocks are suggested from the results. Channel longitudinal profile steepness and concavity indices provide the distribution of anomalously steep channels and also reflect variations in the locus and rate of differential erosion. High steepness and low concavity in a basin underlain by volcanic rocks and a reverse trend in crystalline rocks confirm the observation from the results of basin hypsometric analysis. Keywords Red Sea margin . Basin hypsometry . Steepness index . Erosion . Drainage basins
Introduction River responses to different climatic, lithologic and tectonic settings are fundamental to understand the evolut
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