Schmandt, B. and Gaeuman, D. and Stewart, R. and Hansen, S. M. and Tsai, V. C. and Smith, J. (2017) Seismic array constraints on reach-scale bedload transport. Geology, 45 (4). pp. 299-302. ISSN 0091-7613. http://resolver.caltech.edu/CaltechAUTHORS:20170124-083754227
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Measurements and mechanical models of heterogeneous bedload transport in rivers remain basic challenges for studies of landscape evolution and watershed management. A 700 m reach of the Trinity River (northern California, USA), a large gravel-bed river, was instrumented with an array of 76 seismographs during a dam-controlled ﬂood and gravel augmentation to investigate the potential for out-of-stream monitoring. The temporal response to gravel augmentation during constant discharge provides strong evidence of seismic sensitivity to bedload transport and aids in identification of the seismic frequencies most sensitive to bedload in the study area. Following gravel augmentations, the seismic array reveals a period of enhanced transport that spans most or all of the reach for ∼7–10 h. Neither the duration nor the downstream extent of enhanced transport would have been constrained without the seismic array. Sensitivity to along-stream transport variations is further demonstrated by seismic amplitudes that decrease between the upper and lower halves of the reach consistent with decreased bedload ﬂux constrained by time-lapse bathymetry. Insight into the magnitude of impact energy that reaches the bed is also gained from the seismic array. Observed peak seismic power is ∼1%–5% of that predicted by a model of saltation over exposed bedrock. Our results suggest that dissipation of impact energy due to cover effects needs to be considered to seismically constrain bedload transport rates, and that noninvasive constraints from seismology can be used to test and refine mechanical models of bedload transport.
|Additional Information:||© 2017 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Manuscript received 26 September 2016; Revised manuscript received 27 November 2016; Manuscript accepted 4 December 2016. Seismic data will be openly available through the Incorporated Research Institutions for Seismology Data Management Center (http://ds.iris.edu/ds/nodes/dmc/) beginning in May 2017. Trinity River Restoration Program water and sediment transport data are openly available (http://www.trrp.net). J. Turowski and T. Batholomaus provided helpful reviews. Support from National Science Foundation grant 1554908 (to Schmandt) and grant 1453263 (to Tsai) is acknowledged.|
|Official Citation:||Seismic array constraints on reach-scale bedload transport B. Schmandt, D. Gaeuman, R. Stewart, S.M. Hansen, V.C. Tsai, J. Smith Geology Apr 2017, 45 (4) 299-302; DOI: 10.1130/G38639.1|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||26 Jan 2017 00:43|
|Last Modified:||08 Mar 2017 17:23|
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