Mapping Dynamic Turbidity Maximum Zone of the Yellow River Estuary from 38 Years of Landsat Imagery

Abstract

Turbidity maximum zone (TMZ) plays a crucial role in estuarine ecosystems, exerting effects on erosion, environment evolution and socioeconomic activities in the coastal area. However, the long-term understanding of the TMZ in large river estuary such as the Yellow River estuary is still lacking. In this study, we focus on the TMZ distribution, variation and regulation mechanisms in the Yellow River estuary from different time scales. Based on time series Landsat images during the period 1984 to 2021 and Google Earth Engine (GEE), we proposed a TMZ extracting method in the Yellow River estuary to generate 322 TMZ maps. The overall accuracy of our algorithm reached 97.4%. The results show that there are clear decadal and seasonal TMZ variations during the 38-year period in the Yellow River estuary. Morphology, currents and wind speeds combined with seawater stratification have direct effects on TMZ at different time scales, while the direct impacts of tides and fluvial output of the Yellow River on TMZ are limited. In this article, the highly robust method provides a cost-effective alternative to accurately map the TMZ in global large river estuaries and systematically reveals the spatiotemporal evolution of TMZ, shedding light on the response mechanism of coastal geomorphology, marine ecological environment and biogeochemical cycle.

High Spatiotemporal Resolution River Networks Mapping on Catchment Scale Using Satellite Remote Sensing Imagery and DEM Data

“…The upper reaches of the Yellow River are dominated by mountains, whereas the middle and lower reaches are dominated by plains and hills (Figures 1a–1c), forming the youngest delta in China (Wang et al., 2022). Nearly 90% of the sediment originates from the middle reaches, and 60% of the river runoff originates from the upper reaches (Chang et al., 2022; Wang et al., 2017; Zhu et al., 2021).…”

High Spatiotemporal Resolution River Networks Mapping on Catchment Scale Using Satellite Remote Sensing Imagery and DEM Data

“…The upper reaches of the Yellow River are dominated by mountains, whereas the middle and lower reaches are dominated by plains and hills (Figure 1a-c), forming the youngest delta in China . Nearly 90% of the sediment originates from the middle reaches, and 60% of the river runoff originates from the upper reaches (Wang et al, 2017;Zhu et al, 2021;Chang et al, 2022).…”

Quantification of sedimentation in the Yellow River estuary based on GIS remote sensing technology

“…But during the decade under review, the marine hydrodynamics around the mouth of the Yellow River almost dramatically changed its sedimentation. For the current, they are a low-speed repeated flow transportation effect, forming a whirlpool around the sand spit south of the Yellow River estuary, so the influence of the current is long-term, a large amount of sediment will accumulate in the port south of the Yellow River estuary, and a few will be transported to the northwest [9]. In the Yellow River Delta, the waves caused by the wind mainly follow the wind speed change, and the waves are also one of the reasons for promoting the sediment deposition of the mouth of the Yellow River, which makes the degree of siltation lower than before, and then the sediment inflows the Bohai Sea and even the Pacific Ocean with the tide [4].…”