Tide2Topo: A new method for mapping intertidal topography accurately in complex estuaries and bays with time-series Sentinel-2 images

Chunpeng Chen, Ce Zhang*, Bo Tian, Wenting Wu, Yunxuan Zhou

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

9 Citations (Scopus)

Abstract

Intertidal zones serve as a critical transition between land and ocean and are periodically inundated by tides. They are extremely important to coastal communities as it provides diverse habitats and buffers against marine hazards. However, the reduced river sediment together with sea level rise and coastal reclamation have caused the widespread loss of intertidal areas. Reliable, high-resolution, and up-to-date intertidal topography maps are key information for coastal vulnerability assessment and restoration. Existing approaches to intertidal topography reconstruction involve significant ground surveys, with limited spatial coverage, accuracy, and efficiency, thus, restricting their potential to generalize globally. To address these issues, we propose a pixel-based approach to construct intertidal topography from dense Sentinel-2 satellite time-series and limited ground truth surveys, named as Tide2Topo. Tide2Topo differs conceptually from the widely used waterline method since it considers tidal inundation frequency as a topographic indicator rather than instantaneous waterlines. Therefore, Tide2Topo does not involve manual selection of images at different tide levels. The relationship between intertidal inundation frequency and elevation is calibrated using linear and polynomial models based on a few transect measurements instead of tidal height, preventing errors introduced by inaccurate tidal data. The proposed Tide2Topo was applied and validated in the UK and China over several complicated estuaries and bays with extensive muddy flats or sandy beaches. The results demonstrated that the topography derived from intertidal inundation frequency compared to LiDAR or UAV photogrammetric observations has a root mean square error ranging from 16 to 38 cm. The large errors were found in the tidal channel areas where the inundation frequency calculation was prone to uncertainty. Dense Sentinel-2 time-series observations ensure finer sampling of the tidal cycle, thereby not only eliminating errors caused by spatial interpolation but also maintaining the accuracy of elevation estimations at pixel level. Tide2Topo is a robust, portable and rapid method that is well suited to large-scale intertidal topography reconstruction. Future work could use Sentinel-1 SAR as an alternative data source for Tide2Topo, realizing seasonal or annual monitoring of intertidal geomorphological changes.

Original languageEnglish
Pages (from-to)55-72
Number of pages18
JournalISPRS Journal of Photogrammetry and Remote Sensing
Volume200
DOIs
Publication statusPublished - 1 Jun 2023

Bibliographical note

Funding Information:
This work was supported by the Natural Environment Research Council [grant number NE/T004002/1 ]. The research was partially funded by the project “Coping with Deltas in Transition” within the Programme of Strategic Scientific Alliances between China and the Netherlands (PSA), financed by the Ministry of Science and Technology of the People’s Republic of China (MOST) [grant number 2016YFE0133700], and also sponsored by the China Scholarship Council (CSC).

Publisher Copyright:
© 2023 The Author(s)

Keywords

  • Intertidal topography
  • Sentinel-2
  • Tide inundation
  • Time-series

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