Predicting sediment flux from continental shelf islands, southeastern China
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Predicting sediment flux from continental shelf islands, southeastern China* LI Gaocong1, XIA Xiaoming2, JIA Jianjun3, WANG Yaping3, CAI Tinglu2, GAO Shu3, ** 1
Department of Marine Technology, Guangdong Ocean University, Zhanjiang 524088, China
2
Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China
3
State Key Laboratory for Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
Received Dec. 25, 2019; accepted in principle Feb. 23, 2020; accepted for publication Apr. 21, 2020 © Chinese Society for Oceanology and Limnology, Science Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Continental shelf islands are contributors of terrestrial sediment supply to shelf regions, and the sediment flux from these islands shall be quantified. We calculated the sediment flux of continental shelf islands in the southeastern China using two empirical equations under two preconditions. The first, the sediment load/yield of the islands has the same pattern as the adjacent small, mountainous rivers along the coastline; and the second, each of the islands was treated as a single catchment. The results show that the sediment supply from these islands reached an order of magnitude of 1 Mt/a, which is comparable to the supply from the local smaller rivers. A sensitivity analysis indicates that this value represents the lower limit of estimate; if the accurate amount of sub-catchments of any island is considered, then this value will be enhanced slightly. This study demonstrates that the sediment supply from continental shelf islands to oceans is an important factor affecting the regional sedimentation and, therefore, should be paid with attention. Keyword: continental shelf islands; sediment flux; local rivers; shelf mud deposits; East and South China Seas
1 INTRODUCTION Continental shelf islands are widely distributed in global shallow marine environments. Compared with oceanic islands, generated by submarine volcanic activities, these islands are closely correlated with adjacent continents in geographical and geological settings (Whittaker, 1998; Stankowski and Johnson, 2014). Sediment supply to continental shelves is commonly considered to be dominated by two dominant sources, i.e., riverine and shelf-derived sediments (Nittrouer and Wright, 1994; Gao et al., 2011; Jia et al., 2018). However, shallow marine islands, which can also contribute to the deposits, have been often ignored (Li et al., 2018). In order to quantify the sediment flux from continental shelf islands, long-term hydrologic and sediment observation data is needed. However, it is not available for us to establish empirical equations for the sediment flux calculation of continental shelf islands. One indirect method is to integrate islandwide sediment flux into the continent river-derived
sediment flux because they are linked closely in both geographical and geological settings, especially before influenced by intense human activities. Traditionally, two distinct methods are use
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