Storm surge-induced soil salinization and its impact on agriculture in the coastal area of the Indian Sundarban

The low-lying coastal areas of the Indian Sundarban always face numerous hazards. The saline water intrusion through embankment breaching during storm surges is one of the major challenges for agriculture and livelihood. The present study focused on assessing soil salinity dynamics with storm surges and their impact on agriculture. The study was conducted in the Namkhana block of the Indian Sundarban. A total of 154 soil samples were collected from 77 sampling points at depths of 0–10 and 30–40 cm and the intensity of salinity, considering electrical conductivity (EC), pH, and sodium content was measured. The flood inundation maps of tropical cyclones Amphan (2020) and Yaas (2021) were prepared from Sentinel 1A data. The different topographical zones (i.e., proximal to coast/estuary, proximal to creeks, and central) in both flooded and non-flooded areas are considered to assess the salinity. The Rice growth vegetation index (RGVI) and Normalized difference vegetation index (NDVI) were calculated for the pre-flood and post-flood phases. The results show that the flooded and proximal to creeks or coast areas tend to have very high salinity. The salinity has increased downwards in all topographical zones. The maximum salinity for the flooded area is found at 40 cm depth. The study revealed that there was a significant change in cropland by the cyclone-induced flood and soil salinity. The study can help identify salt-affected areas, cropland damage assessment, and design suitable land use and cropping practices in the future.