Seismologically determined bedload flux during the typhoon season
Abstract
Continuous seismic records near river channels can be used to quantify the energy induced by river sediment transport. During the 2011 typhoon season, we deployed a seismic array along the Chishan River in the mountain area of southern Taiwan, where there is strong variability in water discharge and high sedimentation rates. We observe hysteresis in the high-frequency (5–15 Hz) seismic noise level relative to the associated hydrological parameters. In addition, our seismic noise analysis reveals an asymmetry and a high coherence in noise cross-correlation functions for several station pairs during the typhoon passage, which corresponds to sediment particles and turbulent flows impacting along the riverbed where the river bends sharply. Based on spectral characteristics of the seismic records, we also detected 20 landslide/debris flow events, which we use to estimate the sediment supply. Comparison of sediment flux between seismologically determined bedload and derived suspended load indicates temporal changes in the sediment flux ratio, which imply a complex transition process from the bedload regime to the suspension regime between typhoon passage and off-typhoon periods. Our study demonstrates the possibility of seismologically monitoring river bedload transport, thus providing valuable additional information for studying fluvial bedrock erosion and mountain landscape evolution.
Additional Information
© 2015 Nature Publishing Group. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Received 14 September 2014; Accepted 13 January 2015; Published 5 February 2015. This research has been supported by the National Science Council of the Republic of China (NSC 99-2627-M-002-015). The authors acknowledge the Central Geological Survey (CGS) and Water Resource Agency (WRA), Taiwan, for providing the fluvial data, and the Central Weather Bureau (CWB) and Academia Sinica, Taiwan, for providing the broadband seismic data. The meteorological data was provided by the CWB. The software package GMT (Generic Mapping Tools, http://gmt.soest.hawaii.edu/) was used in making some the figures in this paper. Author contributions: W.A.C. performed the river seismic noise analysis and the inversion of bedload flux. Y.M.W. and L.Z. helped to co-ordinate the deployment of seismic array. W.A.C. and C.H.C. deployed and maintained the seismic array. V.C.T. assisted in implementing the seismic impact forward model. All of the authors contributed to the data acquisition and interpretation, and the writing of this paper.Attached Files
Published - srep08261.pdf
Supplemental Material - srep08261-s1.pdf
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Additional details
- PMCID
- PMC4317699
- Eprint ID
- 55660
- Resolver ID
- CaltechAUTHORS:20150310-084646630
- NSC 99-2627-M-002-015
- National Science Council (Taipei)
- Created
-
2015-03-10Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Seismological Laboratory