Automatic detection of suspected sewage discharge from coastal outfalls based on Sentinel-2 imagery

Wang, Yuxin; He, Xianqiang; Bai, Yan; Tan, Yew Seong; Zhu, Bozhong; Wang, Difeng; Ou, Mengyuan; Gong, Fang; Zhu, Qiankun; Huang, Haiqing

doi:10.1016/j.scitotenv.2022.158374

Cited by 10 publications

(2 citation statements)

References 43 publications

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“…Remote sensing technology has been widely applied to coastal monitoring due to its ability to perform large-scale synchronous observations [ 19 ] and low monitoring costs [ 20 , 21 , 22 ]. For example, it can be used to monitor the coastline [ 23 , 24 ], tidal flats [ 25 , 26 ], and nearshore water bodies [ 27 , 28 , 29 ]. However, there has been less attention paid to monitoring aquaculture ponds, which have been not the focus of researchers, but rather an indirect target of their studies.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Evolution of Aquaculture along the Bohai Sea Coastline and Implications for Eco-Coastal Vegetation Restoration Based on Remote Sensing

Wang,

Liu

2024

Plants

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The expansion and intensification of coastal aquaculture around the Bohai Sea in China has reduced the tidal flats and damaged the coastal vegetation environment. However, there are few studies on the relationship between the evolution of coastal aquaculture and the variability of coastal vegetation, which limits our understanding of the impact of human activities on the coastal ecosystem. In this study, based on remote sensing technology, we firstly used a combination of a neural network classifier and manual correction to monitor the long-term dynamic changes in aquaculture in the Bohai Sea from 1984 to 2022. We then analyzed its evolution, as well as the relationship between the evolution of coastal aquaculture and the variability of coastal vegetation, in detail. Our study had three main conclusions. Firstly, the aquaculture along the coast of the Bohai Sea showed an expanding trend from 1984 to 2022, with an increase of 538%. Secondly, the spatiotemporal changes in the aquaculture centroids in different provinces and cities varied. The centroid of aquaculture in Liaoning Province was mainly distributed in the Liaodong Peninsula, and moved northwest; that in Hebei Province was distributed in the northeast and moved with no apparent pattern; the centroid of aquaculture in Tianjin was mainly distributed in the southeast and moved westward; and the centroid of aquaculture in Shandong Province was mainly distributed in the northwest and moved in a northwesterly direction. Finally, the expansion of aquaculture of the Bohai Sea has increased the regional NDVI and length of the corresponding coastline, and has made coastlines move toward the sea. Our results provide reliable data support and reference for ecologically managing aquaculture and coastal environmental protection in the Bohai Sea.

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Section: Introductionmentioning

confidence: 99%

Dynamic Evolution of Aquaculture along the Bohai Sea Coastline and Implications for Eco-Coastal Vegetation Restoration Based on Remote Sensing

Wang,

Liu

2024

Plants

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“…Even though these satellites were primarily designed for land applications, their freely available higher-resolution data motivated the scientific community to investigate their potential for coastal applications. To date, several studies have reported their successful use in coastal and estuarine environments, i.e., Caballero et al (2018b;2019;2022); Caballero and Stumpf (2020); Cao and Tzortziou (2021); Haro et al (2022); Maimouni et al (2022); Sebastia-Frasquet et al (2019); Wang et al (2022); Zhang et al ( 2021), among others. Caballero et al (2019) showed that the spectral bands of Sentinel-2 and Sentinel-3 in the red-edge and NIR regions allow turbidity detection in optically shallow waters.…”

Section: Introductionmentioning

confidence: 99%

Monitoring turbidity in a highly variable estuary using Sentinel 2-A/B for ecosystem management applications

et al. 2023

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The Guadalquivir estuary (southern Spain) occasionally experiences medium to high turbidity, reaching above 700 Formazin Nephelometric Unit (FNU) during extreme events, thus negatively influencing its nursery function and the estuarine community structure. Although several turbidity algorithms are available to monitor water quality, they are mainly developed for mapping turbidity ranges of 0-100 FNU. Thus, their use in a highly turbid region may not give accurate results, which is crucial for estuarine ecosystem management. To fill this gap, we developed a multi-conditional turbidity algorithm that can retrieve turbidity from 0 to 600 FNU using the Sentinel-2 red and red-edge bands. Four major steps are implemented: atmospheric and sun glint correction of the Level-1C Sentinel-2 data, spectral analysis for different water turbidity levels, regression modelling between in situ turbidity and remote sensing reflectance (Rrs) for algorithm development, and validation of the best-suited model. When turbidity was < 85 FNU, the Rrs increased firstly in the red wavelength (665 nm), but it saturated beyond a certain turbidity threshold (> 250 FNU). At this time, Rrs started to increase in the red-edge wavelength (704 nm). Considering this spectral behavior, our algorithm is designed to automatically select the most sensitive turbidity vs. Rrs, thus avoiding the saturation effects of the red bands at high turbidity levels. The model showed good agreement between the satellite derived turbidity and the in situ measurements with a correlation coefficient of 0.97, RMSE of 15.93 FNU, and a bias of 13.34 FNU. Turbidity maps derived using this algorithm can be used for routine turbidity monitoring and assessment of potential anthropogenic actions (e.g., dredging activities), thus helping the decision-makers and relevant stakeholders to protect coastal resources and human health.

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A Critical Review of Remote Sensing Methods for Inland Water Quality Monitoring: Progress, Limitations, and Future Perspectives

Raghul,

Porchelvan

2024

Water Air Soil Pollut

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Automatic detection of suspected sewage discharge from coastal outfalls based on Sentinel-2 imagery

Cited by 10 publications

References 43 publications

Dynamic Evolution of Aquaculture along the Bohai Sea Coastline and Implications for Eco-Coastal Vegetation Restoration Based on Remote Sensing

Dynamic Evolution of Aquaculture along the Bohai Sea Coastline and Implications for Eco-Coastal Vegetation Restoration Based on Remote Sensing

Monitoring turbidity in a highly variable estuary using Sentinel 2-A/B for ecosystem management applications

A Critical Review of Remote Sensing Methods for Inland Water Quality Monitoring: Progress, Limitations, and Future Perspectives

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