Table 1 Details of the data sources used to generate a digital bathymetric elevation model for the Adam’s Bridge.

ICESat-2 ATL03

• Ground tracks: 584, 653, 1026, 1095, 81, 150, and 523.

• Preferred acquisitions: January to May (low turbid period) and mostly night-time acquisitions.

• Refraction-corrected photons returned from the seafloor were used to compute the bathymetry.

• Elevations from the bare earth returned photons were used to estimate the digital elevation model for the land part.

• ICESat-2 Approximately 0.2 million ICESat-2 photons representing the seafloor’s depths and terrain elevations were collected as a part of data collection.

https://nsidc.org/data/icesat-2 or https://openaltimetry.earthdatacloud.nasa.gov/data/

Sentinel-3A/B

• Correspondingly, for the exact dates acquired by the ICESat-2, within +/− 24 hours, Level-2 OLCI data products from the Sentinel-3 A/B mission were used to retrieve K_d(490).

• Kd(490) data is used to assess the turbid load in the study area. Only those acquisitions of ICESat-2 were considered while K_d(490) < 0.12 m⁻¹, i.e., clear water conditions.

https://sentinels.copernicus.eu

Sounding depths from Electronic Navigational Charts (ENCs)

To increase the density of points representing the seafloor’s depth in the study area, sounding depths were digitized from the following ENCs datasets

ENC No: IN2262AB at Scale: 300000

ENC No: IN3316AA at Scale: 150000

ENC No: IN53016M at Scale: 37500

Chart No: 3016 at Scale: 37500

Chart No: 3040 at Scale: 50000

These charts are issued by hydrographic offices, as per the International Hydrographic Organisation’s (IHO) standards, specifications, and symbol sets.

https://hydrobharat.gov.inhttps://iho.int

Forest And Buildings removed Copernicus DEM (FABDEM)

Towards densification of elevation points for the extent of the area having the land part (like Rameshwaram and Talai Mannar Islands), elevation values from FABDEM were used.

https://data.bris.ac.uk