Tracking the dynamics of tidal wetlands with time-series satellite images in the Yangtze River Estuary, China

ABSTRACT

Tidal wetlands provide a variety of ecosystem services to coastal communities but suffer severe losses due to anthropogenic activities in the Yangtze River Estuary (YRE). However, the detailed dynamics of tidal wetlands have not been well studied with sufficient spatiotemporal resolution. Here, we proposed a rapid classification method that integrates the COntinuous monitoring of Land Disturbance (COLD) algorithm and Median Composite (MC) based on the dense Landsat time series to track the dynamic processes of tidal wetlands in the YRE from 1990 to 2020. The results showed that the COLD-MC demonstrated remarkable effectiveness in detecting the change of tidal wetlands and excellent overall accuracy and kappa coefficient ranging from 90% to 96% and 0.89–0.95, respectively. The overall accuracy of change detection was 97% with an absolute error of 0.4 years. We found that the total area of tidal wetlands experienced a net loss of 59.75 km² in the YRE, but the gain and loss of the study period were 1556.07 and 1615.82 km², respectively. Land reclamation, sediment reduction, and Spartina alterniflora invasion pose significant threats to tidal wetlands. Sustainable management could be implemented through the establishment of nature reserves and ecological sediment enhancement engineering projects.

KEYWORDS:

• Tidal wetlands
• landsat time-series
• COLD-MC
• dynamic equilibrium
• land reclamation
• sediment starvation

Acknowledgment

This research was funded by the National Natural Science Foundation of China (Grant No. 42301540), the Open Research Fund of State Key Laboratory of Estuarine and Coastal Research (Grant number SKLEC-KF202307), the Natural Science Foundation of Fujian Province (Grant No. 2022J05024), the Education Department of Fujian Province (Grant No. JAT210027), and the Natural Science Foundation for Distinguished Young Scholars of Fujian Province, China (Grant No. 2021J06014).

Data availability statement

The data presented in this study are available on request from the corresponding author.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded by the National Natural Science Foundation of China (grant number 42301540), the Open Research Fund of State Key Laboratory of Estuarine and Coastal Research (grant number SKLEC-KF202307), the Natural Science Foundation of Fujian Province (grant number 2022J05024), the Education Department of Fujian Province (grant number JAT210027), and the Natural Science Foundation for Distinguished Young Scholars of Fujian Province, China (grant number 2021J06014).