Multi-Year Winter Variations in Suspended Sediment Flux through the Bohai Strait

Abstract

The Bohai Strait is the only channel that allows material exchanges between the Bohai Sea and the Yellow Sea. It is also the only channel for the transportation of materials from the Yellow River to the Yellow Sea and the East China Sea. The supply of suspended sediment from the Bohai Sea plays a decisive role in the evolution of the mud area in the northern Yellow Sea and even the muddy area in the southern Yellow Sea. Previous studies have demonstrated that sediment exchange through the Bohai Strait occurs mainly in winter, but due to the lack of long-term observational data, changes in the sediment flux over multiple years have not been studied. In this paper, based on L1B data from the MODIS (Moderate Resolution Imaging Spectroradiometer) -Aqua satellite, an interannual time series of the suspended sediment concentration (SSC) at each depth layers in the Bohai Strait in winter was established through 16 cruises that benefited from the complete vertical mixing water in the strait in winter. The numerical model FVCOM, (Finite-Volume Community Ocean Model) which is forced by the hourly averaged wind field, reflected the effect of winter gales. With the model simulated winter current from 2002 to the present and the SSC at each layer, multi-year winter suspended sediment flux data were obtained for the Bohai Strait. This study found that in the winter, the suspended sediment output from the Bohai Sea to the Yellow Sea through the southern part of the Bohai Strait, while the suspended sediment input from the Yellow Sea to the Bohai Sea is through the northern part. In terms of long-term changes, the net flux ranged between 1.22 to 2.70 million tons in winter and showed a weak downward trend. The output flux and input flux both showed an upward trend, but the increase rate of the input flux was 51,100 tons/year, which was higher than the increase of the output flux rate (46,100 tons/year). These changes were mainly controlled by the increasing strength of east component of winter wind. And the weak decrease in net flux is controlled by the difference of output and input flux.

Winter and summer sedimentary dynamic process observations in the sea area off Qinhuangdao in the Bohai Sea, China

“…Consequently, in recent decades, the high SSC in the Bohai Sea has been widely studied, especially Mao et al (2018) and Zhao et al (2022) considered the entire Bohai Sea. Since the majority of previous studies have concentrated on the resuspension, transportation and final destination of Huanghe River-derived sediment and its seasonal variability, most researchers have focused on specific areas such as the Huanghe Estuary (Li et al, 2010;Qiao et al, 2010;Yang et al, 2011;Wang et al, 2014;Liu et al, 2020a), the Bohai Strait (Duan et al, 2020b;Liu et al, 2020b;Wang et al, 2020), and the Bohai Bay (Qiao et al, 2011), and paid minimal academic attention to other sea areas, such as the exceptional low SSC area off Qinhuangdao (Figure 1B).…”

Monitoring Suspended Sediment Concentration in the Yellow River Estuary and Its Vicinity Waters on the Basis of SDGSAT-1 Multispectral Imager

“…Extensive prior research has established remote sensing technology as an effective means of measuring water quality parameters [4,5]. Several satellite sensors, including the Coastal Zone Color Scanner (CZCS), Sea-viewing Wide Field of View Sensor (Sea-WIFS), Moderate Resolution Imaging Spectroradiometer (MODIS), Hyperspectral Imager for the Coastal Ocean (HICO), and Coastal Zone Imager (CZI), are currently utilized for the inversion of suspended sediment concentration (SSC) in water color remote sensing [8][9][10][11][12][13][14]. However, the spatial resolution of these marine color sensors is relatively low, which makes it difficult to achieve fine-scale monitoring of water quality parameters.…”