Journal of Tropical Oceanography ›› 2025, Vol. 44 ›› Issue (5): 140-153.doi: 10.11978/2024218CSTR: 32234.14.2024218

• Marine geomorphology • Previous Articles     Next Articles

Study on remote sensing monitoring and time series change of shallow sea topography of typical islands and reefs in the South China Sea*

CHEN Yuchen1(), FU Dongyang1(), TAO Bangyi2, LI Jizhe2, ZHU Yixian2, LIU Bei1, LIN Ye1, CHAI Xia1   

  1. 1. College of Electronics and Information Engineering, Guangdong Ocean University, Zhanjiang 524088, China
    2. State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China
  • Received:2024-11-26 Revised:2025-01-25 Online:2025-09-10 Published:2025-10-14
  • Contact: FU Dongyang
  • Supported by:
    National Key Research and Development Program of China(2022YFC3103101); Guangdong Provincial Laboratory of Southern Ocean Science and Engineering (Guangzhou) Major Project Team(GML2021GD0809); National Natural Science Foundation of China(42206187); Key Research Project of Guangdong Provincial Department of Education(2023ZDZX4009)

Abstract:

The Nansha Islands, located in the southern part of the South China Sea, hold significant strategic importance for China’s maritime rights and interests, development strategy, and national security due to its geographical location. It is of great significance to national strategy to carry out research on water depth monitoring and topographic changes of Nansha Islands and reefs. In this study, combined with Sentinel-2 and ICESat-2 (ice, cloud, land elevation satellite-2) data, an active-passive fusion remote sensing sounding algorithm was used to invert the shallow sea topography of the Bai Jiao and Beizi Dao areas in the Nansha Islands. This method enables time series analysis to reveal long-term trends and short-term fluctuations in water depth and reef terrain, providing new insights into the impacts of human activities and natural factors on reef topography changes. The research results are as follows: 1) A high-precision water depth inversion model was validated, showing excellent performance in the study area (R2 > 0.9, MAE < 0.4 m, RMSE < 0.7 m). 2) From 2018 to 2024, both Bai Jiao and Beizi experienced varying degrees of terrain and spatial structure changes. Due to reclamation projects, the land area of Bai Jiao increased, whereas Beizi Dao’s changes were influenced by natural factors, exhibiting dynamic variations. 3) The topographic changes of Bai Jiao were mainly driven by human factors, including land reclamation and resource exploitation, while Beizi Dao’s changes mainly resulted from natural factors such as monsoons, typhoons, seawater erosion, and sediment deposition. This study demonstrates the effectiveness of active-passive fusion bathymetry, providing a valuable reference for efficient water depth and terrain detection of typical reefs in China. Moreover, it offers crucial technical support for long-term spatiotemporal monitoring of shallow sea terrain in areas such as the Nansha Islands.

Key words: South China Sea islands and reefs, Sentinel-2, ICESat-2, bathymetric inversion, spatiotemporal monitoring

CLC Number: 

  • P737.13