A Study on Remote Sensing Monitoring of Nearshore Turbidity in Hong Kong Based on Sentinel-2

Meng Qian; Huang Jue

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Meng Qian，Huang Jue. A Study on Remote Sensing Monitoring of Nearshore Turbidity in Hong Kong Based on Sentinel-2[J]. Haiyang Xuebao，2025, 47(x)：1–13

Citation:

Meng Qian，Huang Jue. A Study on Remote Sensing Monitoring of Nearshore Turbidity in Hong Kong Based on Sentinel-2[J]. Haiyang Xuebao，2025, 47(x)：1–13

Citation:

Meng Qian，Huang Jue. A Study on Remote Sensing Monitoring of Nearshore Turbidity in Hong Kong Based on Sentinel-2[J]. Haiyang Xuebao，2025, 47(x)：1–13

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A Study on Remote Sensing Monitoring of Nearshore Turbidity in Hong Kong Based on Sentinel-2

Meng Qian,
Huang Jue^,

College of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao 266590, China

Received Date: 2024-10-29
Accepted Date: 2025-01-22

Available Online: 2025-02-21

Abstract

Abstract

Turbidity is a reliable indicator for assessing water quality conditions. Turbidity monitoring can effectively reflect the health status of water bodies and guarantee the sustainable development of ecosystems and the safe utilization of water resources. In this study, Sentinel-2 MSI images from 2016 to 2023 were employed in the construction of a quantitative inversion model based on measured data. The temporal and spatial distribution characteristics and variation rules of water turbidity in the Hong Kong coastal waters over the past eight years were analyzed, and the main influencing factors were explored. In comparison to the traditional empirical model, random forest (RF) model, gradient boosted decision tree (GBDT) model, and K Nearest Neighbor (KNN) model, the RF-based turbidity inversion model had the highest accuracy (R² = 0.708, RMSE = 1.774 NTU, MAE = 1.439 NTU). The results demonstrate that the annual average turbidity of the water body fluctuates between 4.02 and 4.16 NTU, exhibiting a downward trend over the past eight years (-0.0243 NTU/a). Additionally, the spatial distribution is high in the north-west and low in the south-east. The seasonal average water turbidity, in descending order, was as follows: winter (4.54 NTU), autumn (4.03 NTU), spring (3.86 NTU) and summer (3.76 NTU). Utilizing meteorological data and investment data on sewage treatment in Hong Kong, we analyzed the factors affecting the spatial and temporal distribution of turbidity in terms of the natural environment and human activities. Turbidity in Hong Kong's offshore waters exhibits a negative correlation with inlet runoff and air temperature. Additionally, it is influenced by the anthropogenic factor of sewage treatment in Hong Kong. Furthermore, there is a significant correlation between precipitation and wind speed during the period of tropical cyclone activity and the change in turbidity in the water column.
- Hong Kong offshore waters,
- turbidity,
- Sentinel-2,
- remote sensing retrieval,
- spatial and temporal distribution

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References(33)

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