Bathymetric maps from multi-temporal analysis of Sentinel-2 data: the case study of Limassol, Cyprus

Abstract

Abstract. During the last years, various methods and techniques have been used to estimate the seafloor topography with high accuracy. The topography is considered an important component for marine applications since several activities and infrastructures are being carried out at the bottom, column and surface of the sea. In this, study, freely and open distributed optical satellite images were used to obtain bathymetric data for shallow waters, (until 30 m below sea level) based on timeseries analysis of multispectral Sentinel-2 datasets. The ratio transform algorithm was implemented for twelve (12) monthly images covering thus a whole year. The different generated Digital Terrain Models (DTMs) were compared with high resolution LIDAR measurements. The results showed that bathymetry can be obtained from satellite data within a Root Mean Square Error (RMSE) ranging from 1.39 up to 2.56 m while more accurate results were generated during the summer period.

Towards Routine Mapping of Shallow Bathymetry in Environments with Variable Turbidity: Contribution of Sentinel-2A/B Satellites Mission

“…The multi-scene compositing approach addressed limitations inherent in conventional methods and reduced the impact of turbidity, performing better than the standard "pick the best scene" method that relies on a single image (Figures 3 and 4c vs. Figure 4a in Cape Lookout; and Figure 10e vs. Figure 10a,c in Saint Joseph Bay). The final corrected SDB produced robust depths up to the limit of the lidar surveys, with typical errors ≤0.4 m. These excellent results from Sentinel-2 compared favorably with those produced in relatively low turbidity water in south Florida [22,44], and in regions with transparent waters [10,18,20,30]. Whereas some researchers suggested there is still work to be performed regarding the identification of the optimal period throughout the year where bathymetric errors are minimized [18,29], others asked for novel strategies to allow seabed mapping without the laborious analysis per image and the visual inspection of the "clearest scene" [19].…”

“…The final corrected SDB produced robust depths up to the limit of the lidar surveys, with typical errors ≤0.4 m. These excellent results from Sentinel-2 compared favorably with those produced in relatively low turbidity water in south Florida [22,44], and in regions with transparent waters [10,18,20,30]. Whereas some researchers suggested there is still work to be performed regarding the identification of the optimal period throughout the year where bathymetric errors are minimized [18,29], others asked for novel strategies to allow seabed mapping without the laborious analysis per image and the visual inspection of the "clearest scene" [19]. Recent studies have already indicated the potential of multi-scene approaches in order to select the optimal scene or eliminate noise over clear waters [16,17,19,20].…”

“…These This paper proposes the first multiple-image technique with Sentinel-2A and Sentinel-2B that allows semi-automated SDB estimation in areas of variable turbidity. Although some recent works have already obtained accurate results with Sentinel-2 and similar satellites, they were implemented in regions with transparent waters [18][19][20]29,30]. We focus on application of the log ratio model [31] because it was designed to support routine mapping in areas with extremely limited calibration data.…”

“…There have been previous studies inspecting water quality issues on SDB [11][12][13][14][15]. Recent studies have already indicated the potential of multi-scene approaches in order to eliminate noise over clear waters [16][17][18][19][20]. The impact of turbidity on SDB is not random and often appears as a false shoal [21,22].…”

Preface: Earth surveillance and space-based monitoring of the environment: integrated approaches

“…A summary of each paper is given in the following. Gomes and Almeida (2019) employed Apatite fissiontrack (AFT) analyses to Southern Brazil and Uruguay samples, aiming to understand the low temperature history of the Dom Feliciano Belt Segment. Twenty-four samples were dated, and confined track lengths of twenty samples were measured.…”