Sustained increase in suspended sediments near global river deltas over the past two decades

Xuejiao Hou; Danghan Xie; Lian Feng; Fang Shen; Jaap H Nienhuis

doi:10.1038/s41467-024-47598-6

Sustained increase in suspended sediments near global river deltas over the past two decades

Nat Commun. 2024 Apr 18;15(1):3319. doi: 10.1038/s41467-024-47598-6.

Authors

Xuejiao Hou^{1

2}, Danghan Xie^{2

3}, Lian Feng⁴, Fang Shen⁵, Jaap H Nienhuis⁶

Affiliations

¹ School of Geospatial Engineering and Science, Sun Yat-Sen University, Guangzhou, China.
² Department of Physical Geography, Utrecht University, Utrecht, the Netherlands.
³ Department of Earth and Environment, Boston University, Boston, MA, USA.
⁴ School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China. fengl@sustech.edu.cn.
⁵ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China.
⁶ Department of Physical Geography, Utrecht University, Utrecht, the Netherlands. j.h.nienhuis@uu.nl.

Abstract

River sediments play a critical role in sustaining deltaic wetlands. Therefore, concerns are raised about wetlands' fate due to the decline of river sediment supply to many deltas. However, the dynamics and drivers of suspended sediment near deltaic coasts are not comprehensively assessed, and its response to river sediment supply changes remains unclear. Here we examine patterns of coastal suspended sediment concentration (SSC) and river sediment plume area (RPA) for 349 deltas worldwide using satellite images from 2000 to 2020. We find a global increase in SSC and RPA, averaging +0.46% and +0.48% yr^-1, respectively, with over 59.0% of deltas exhibiting an increase in both SSC and RPA. SSC and RPA increases are prevalent across all continents, except for Asia. The relationship between river sediment supply and coastal SSCs varies between deltas, with as much as 45.2% of the deltas showing opposing trends between river sediments and coastal SSCs. This is likely because of the impacts of tides, waves, salinity, and delta morphology. Our observed increase in SSCs near river delta paints a rare promising picture for wetland resilience against sea-level rise, yet whether this increase will persist remains uncertain.