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Open AccessArticle

Sediment-Mass Accumulation Rate and Variability in the East China Sea Detected by GRACE

Department of Civil Engineering, National Chiao Tung University, 1001 Ta Hsueh Rd., Hsinchu 300, Taiwan
Department of Earth Sciences, National Taiwan Normal University, 88, Sec. 4, Tingzhou Rd., Taipei City 116, Taiwan
Department of Real Estate and Built Environment, National Taipei University, 151, Daxue Rd., Taipei City 237, Taiwan
School of Engineering, Faculty of Engineering and Built Environment, University of Newcastle, Callaghan 2308, Australia
Author to whom correspondence should be addressed.
Academic Editors: Xiaofeng Li and Prasad S. Thenkabail
Remote Sens. 2016, 8(9), 777;
Received: 17 June 2016 / Revised: 30 August 2016 / Accepted: 9 September 2016 / Published: 20 September 2016
The East China Sea (ECS) is a region with shallow continental shelves and a mixed oceanic circulation system allowing sediments to deposit on its inner shelf, particularly near the estuary of the Yangtze River. The seasonal northward-flowing Taiwan Warm Current and southward-flowing China Coastal Current trap sediments from the Yangtze River, which are accumulated over time at rates of up to a few mm/year in equivalent water height. Here, we use the Gravity Recovery and Climate Experiment (GRACE) gravity products from three data centres to determine sediment mass accumulation rates (MARs) and variability on the ECS inner shelf. We restore the atmospheric and oceanic effects to avoid model contaminations on gravity signals associated with sediment masses. We apply destriping and spatial filters to improve the gravity signals from GRACE and use the Global Land Data Assimilation System to reduce land leakage. The GRACE-derived MARs over April 2002–March 2015 on the ECS inner shelf are about 6 mm/year and have magnitudes and spatial patterns consistent with those from sediment-core measurements. The GRACE-derived monthly sediment depositions show variations at time scales ranging from six months to more than two years. Typically, a positive mass balance of sediment deposition occurs in late fall to early winter when the southward coastal currents prevail. A negative mass balance happens in summer when the coastal currents are northward. We identify quasi-biennial sediment variations, which are likely to be caused by quasi-biennial variations in rain and erosion in the Yangtze River basin. We briefly explain the mechanisms of such frequency-dependent variations in the GRACE-derived ECS sediment deposition. There is no clear perturbation on sediment deposition over the ECS inner shelf induced by the Three Gorges Dam. The limitations of GRACE in resolving sediment deposition are its low spatial resolution (about 250 km) and possible contaminations by land hydrological and oceanic signals. Potential GRACE-derived sediment depositions in six major estuaries are presented. View Full-Text
Keywords: East China Sea; GRACE; mass accumulation rate; sediment deposition; Yangtze River East China Sea; GRACE; mass accumulation rate; sediment deposition; Yangtze River
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Liu, Y.-C.; Hwang, C.; Han, J.; Kao, R.; Wu, C.-R.; Shih, H.-C.; Tangdamrongsub, N. Sediment-Mass Accumulation Rate and Variability in the East China Sea Detected by GRACE. Remote Sens. 2016, 8, 777.

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