Monitoring coastline variations in the Pearl River Estuary from 1978 to 2018 by integrating Canny edge detection and Otsu methods using long time series Landsat dataset

CATENA ◽  
2022 ◽  
Vol 209 ◽  
pp. 105840
Author(s):  
Xinyi Hu ◽  
Yunpeng Wang
2020 ◽  
Author(s):  
xiaowen luo ◽  
Hui Gao ◽  
Ziyin Wu ◽  
Shoujun Li ◽  
Jihong Shang ◽  
...  

Abstract Due to the influence of human activity and changes in natural conditions, the Pearl River Estuary (PRE) has emerged as a large-scale area of land subsidence, which represents a serious threat to the quality of human life and sustainable socio-economic development. In response to the problems associated with the lack of man-made targets of traditional time-series Interferometric Synthetic Aperture Radar (InSAR) in estuaries and other coastal areas, a distributed scatterers (DS) InSAR method based on a spatially adaptive filter and an eigendecomposition algorithm to estimating the optimal phase of statistically homogeneous DS was applied to obtain subsidence data using 67 scenes Sentinel-1A SAR images covering the PRE. The temporal and spatial distribution characteristics of land subsidence were analyzed. The results suggest that land subsidence in the PRE was widespread and unevenly distributed with large differences between 2015 and 2018. The northwest and southeast are the main subsidence areas, with a maximum sedimentation rate greater than 25 mm/year.


Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 435
Author(s):  
Fenfen Liu ◽  
Tonghui Zhang ◽  
Haibin Ye ◽  
Shilin Tang

The Hong Kong-Zhuhai-Macau Bridge crosses the Pearl River Estuary and is the largest bridge and tunnel project in the world. During the construction period of this project, the excessive suspended sediment was found in the construction region. The suspended sediment generated by sand excavation in the upstream was assumed to have a significant impact on the suspended sediment in the tunnel region. In this study, we assessed the impact of upstream sand excavation on the suspended sediment in the Hong Kong-Zhuhai-Macau Bridge construction area using Landsat OLI, ETM+, and TM data. Regional suspended sediment algorithms were developed for Landsat using a symbolic regression method based on data from in situ measurements in the study area from 2003 to 2014. A band shift was conducted on the remote sensing reflectance data from Landsat ETM+ and OLI to produce a time series of the suspended sediment concentrations that was internally consistent with that of the Landsat TM data. The suspended sediment distribution was extracted and used to compare under two different conditions, with and without sand excavation. The correlations of the time series of the suspended sediment concentrations in different regions in the surrounding waters, including the correlations between the construction regions and the sand excavation regions, were calculated. Our results indicated that the sand excavation north of the Pearl River Estuary had a limited impact on the surface suspended sediment concentrations in the Hong Kong-Zhuhai-Macau Bridge tunnel area.


2019 ◽  
Vol 29 (4) ◽  
pp. 861-875
Author(s):  
Zeyu Zeng ◽  
William W. L. Cheung ◽  
Shiyu Li ◽  
Jiatang Hu ◽  
Ying Wang

2021 ◽  
Vol 9 (2) ◽  
pp. 131
Author(s):  
Dongliang Wang ◽  
Lijun Yao ◽  
Jing Yu ◽  
Pimao Chen

The Pearl River Estuary (PRE) is one of the major fishing grounds for the squid Uroteuthis chinensis. Taking that into consideration, this study analyzes the environmental effects on the spatiotemporal variability of U. chinensis in the PRE, on the basis of the Generalized Additive Model (GAM) and Clustering Fishing Tactics (CFT), using satellite and in situ observations. Results show that 63.1% of the total variation in U. chinensis Catch Per Unit Effort (CPUE) in the PRE could be explained by looking into outside factors. The most important one was the interaction of sea surface temperature (SST) and month, with a contribution of 26.7%, followed by the interaction effect of depth and month, fishermen’s fishing tactics, sea surface salinity (SSS), chlorophyll a concentration (Chl a), and year, with contributions of 12.8%, 8.5%, 7.7%, 4.0%, and 3.1%, respectively. In summary, U. chinensis in the PRE was mainly distributed over areas with an SST of 22–29 °C, SSS of 32.5–34‰, Chl a of 0–0.3 mg × m−3, and water depth of 40–140 m. The distribution of U. chinensis in the PRE was affected by the western Guangdong coastal current, distribution of marine primary productivity, and variation of habitat conditions. Lower stock of U. chinensis in the PRE was connected with La Niña in 2008.


Harmful Algae ◽  
2012 ◽  
Vol 13 ◽  
pp. 10-19 ◽  
Author(s):  
Ping-Ping Shen ◽  
Ya-Nan Li ◽  
Yu-Zao Qi ◽  
Lv-Ping Zhang ◽  
Ye-Hui Tan ◽  
...  

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