Abstract:
Mangroves are among the most productive coastal ecosystems in the world, comprising unique plant
species that play important ecological roles, provide ecosystem services, and deliver socioeconomic
benefits. However, they are highly vulnerable to a range of natural and anthropogenic threats, leading
to significant degradation of their cover and ecological stability. Although precise data on ecosystem
distribution is essential for conservation, a significant knowledge gap exists in Northern Sri Lanka,
where mangrove dynamics remain insufficiently documented. This study assessed the status and
temporal dynamics of mangroves along the coasts of the Jaffna Lagoon using Geographic Information
System (GIS) and Remote Sensing (RS) techniques, focusing on 2002, 2013, and 2024 to represent
approximately two decades of changes. The above selected low tidal cloud-free imageries (30×30 m
resolution) were processed after the pre-processing analysis of the atmospheric and radiometric
corrections. An unsupervised classification was performed using the ISODATA clustering method in
ArcGIS Pro 3.4.0, supported by Global Positioning System (GPS)-based validation. The accuracy
evaluation ranges for the overall Kappa Coefficient exceeded 87%. Results revealed a non-linear trend
in mangrove cover, with a slight decline from 1,420 ha in 2002 to 1,396 ha in 2013 (~1.72%), followed
by a substantial increase to 1,683 ha in 2024, representing an overall gain of approximately 18.5%.
Spatial analysis identified Kavutharimunai (~555.8 ha) and Pooneryn-Nallur (~530.1 ha) as key
mangrove hotspots in 2024. In addition, Mandaitivu exhibited notable expansion (~61%) between 2002
and 2024. The initial decline (2002-2013) is attributed to anthropogenic pressures, including
aquaculture expansion, coastal development projects, and post-conflict resettlement, as well as natural
factors. The post-2013 recovery likely reflects the combined effects of government-led restoration
initiatives, policy enforcement, and natural regeneration. These findings provide a valuable baseline for
sustainable mangrove management and conservation planning in Jaffna Lagoon, Northern Sri Lanka.
