Land Use and Land Cover Dynamics and Environmental Impacts in Garanduwa Lagoon, Weligama, Sri Lanka (2013–2023)

Abstract

Garanduwa Lagoon, located within the Weligama Divisional Secretariat in southern Sri Lanka, is one of the remaining ancient mangrove ecosystems and holds significant ecological and cultural value within the locality. However, increasing human activities and unplanned land use changes have threatened the sustainability of the lagoon ecosystem, yet limited research has been conducted to monitor these changes over time. This study examines land use and land cover changes within a 1 km buffer around the lagoon from 2013 to 2023. Landsat satellite imagery from both years were analyzed using GIS and supervised classification to map and quantify land cover changes. Furthermore, a community survey was conducted among 120 participants residing within the 1 km buffer area surrounding the lagoon. The survey aimed to identify the drivers of land use change and evaluate their associated impacts. The results show a noticeable expansion of commercial land (50% increase) due to tourism expansion. The community survey points to the perceived drivers of change as unregulated tourism development (37%), mangrove removal (29%), and rapid urbanization (21%). Respondents also highlighted key impacts, including overfishing, agricultural runoff, land reclamation, and widespread pollution. They particularly emphasized the dumping of solid waste and plastics into the lagoon. Weak law enforcement, the absence of clear conservation boundaries, and limited community engagement emerged as major governance gaps. These findings underscore an urgent need for integrated land use planning, stronger regulations, and locally led conservation. Without timely action, the lagoon’s ecological health and the livelihoods and cultural heritage it supports face serious and potentially irreversible degradation.