RAS question
Pallikaranai Marsh in Chennai, a Ramsar Site, faces which primary threat?
Correct answer: (B) Urban encroachment and solid waste dumping.
Pallikaranai Marsh in Chennai is primarily threatened by urban encroachment, solid waste dumping, sewage discharge and related urban pressures.
Explanation
Pallikaranai Marsh is one of Chennai’s last remaining natural wetlands, with a Ramsar Site area of 1,247.5 hectares and a Ramsar designation year of 2022. The Ramsar-hosted management plan supports the answer because it traces the marsh’s degradation to urban pressures: construction of institutions, the Perungudi dump-yard, a sewage treatment plant, IT corridors and residential complexes reduced and fragmented it. Unplanned urbanisation, destructive reclamation and dumping of solid and liquid waste cut the marsh to about one-tenth of its original extent. The threat is therefore not a natural hazard but sustained urban intrusion, waste disposal and sewage-linked pollution.
Why the other options are wrong
- (A) Earthquake damage does not match the stated threat pattern, and the question data notes that Chennai is not in a major earthquake zone.
- (C) Glacier retreat cannot explain degradation at Pallikaranai Marsh because the question data itself notes that Chennai has no glaciers.
- (D) Desert expansion is not the relevant pressure on this site, since the question data identifies Chennai as coastal rather than desert terrain.
Concept
This tests Environment & Ecology through Ramsar wetlands and anthropogenic degradation of an urban wetland. For RAS preparation, read it as a site-status-plus-threat question, not merely a location fact.