Reworking of basin fill deposits along a tributary of the upper Yellow River: Implications for changes to landscape connectivity |
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| Authors: | Tami Nicoll Gary Brierley |
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| Institution: | School of Environment, University of Auckland, Auckland, New Zealand |
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| Abstract: | Recent emphasis on sediment connectivity in the literature highlights the need for quantitative baseline studies on the patterns and distribution of sediment stores to facilitate understanding of how sediment moves through the landscape at various temporal and spatial scales. This study evaluates the distribution and make‐up of sediment stores within the dramatically incised landscapes of the upper Yellow River, where basin fill deposits up to 1200 m in depth have been extensively reworked following incision by the Yellow River. Field and GIS analyses highlight the discontinuous distribution of sediment stores in Garang catchment, a 236 km2 tributary of the upper Yellow River. Volumetric estimates of sediment storage were obtained through a combination of field mapping, GPR transects, and GIS analyses. Sediment stores cover 20% of the Garang catchment, with an estimated volume of 474.0 × 106 m3, and inferred residence times from OSL and 14C dating of 103–104 years. Fans and terraces reworked from basin fill deposits, and associated cut and fill terrace features, are the dominant forms of sediment storage (~90% of total). A space‐for‐time argument is used to assess stages of basin infilling and subsequent landscape responses to incision, outlining a dramatic example of changes to sediment dynamics and connectivity relationships within the upper Yellow River. Sediments within the upper catchment lie above the regional basin fill level, offering a glimpse of pre‐incisional conditions. This contrasts markedly with the enduring influence of basin incisional history seen within the middle catchment, and the contemporary landscapes of the lower catchment where nearly all available sediment has been excavated from the basin and the landscape effectively operates under post‐incisional conditions. The need to contextualise catchment‐scale studies in terms of landscape history is emphasised. Copyright © 2017 John Wiley & Sons, Ltd. |
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| Keywords: | sediment storage sediment reworking sediment connectivity incision landscape evolution |
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