Exploring the Seasonal Variability of the Ecosystem Quality in the Sagar Islands of the Indian Sundarbans

Abstract

The natural ecosystem of Sagar Island in the Indian Sundarbans determines coastal resilience by affecting seasonal transformations. The study tracks ecosystem quality patterns through geo-environmental indices including VCI, TCI, VHI, WCI, SCI, and SAVCI based on remote sensing data. EDAS model processing produces Ecosystem Quality Index (EQI) measurements throughout pre-monsoon and post-monsoon seasons from 2014 to 2023. A joint application of simple moving averages combined with Mann–Kendall tests confirms ecosystem quality declined constantly until it hit its maximum decline in 2018 due to cyclonic events. The data indicates that pre-monsoon period EQI values decline as environmental stress improves during the post-monsoon season. The study reveals an ecosystem sensitive zone (ESZ) combining all modeling output, about 27.37% of the area is highly sensitive, and 9.01% of the area is under a very highly sensitive zone of the island. The study found that ecosystem quality on Sagar Island declines significantly during pre-monsoon seasons, with 2018 being the worst year due to cyclones. A decade-long negative trend was confirmed, with over 36% of the island classified as ecologically sensitive. These findings prove that efficient management systems should unite improved water resource control measures with mangrove restoration projects to overcome climate change impacts. Knowledge obtained through investigations enables sustainable management of sensitive coastal environments across different time intervals.