On Factors Influencing Ground Subsidence: A Case Study of Munroe Island

Abstract

Munrothuruthu (‘Munroe Island’) is a place renowned for continuous settlement, in the Kollam district of Kerala. The Indian Ocean earthquake and Tsunami of 2004 triggered this major problem. The island is located at confluence of the Ashtamudi Lake and the Kallada River. Low lying regions of the island are facing progressive settlement which has become pronounced since the occurrence of Tsunami. The area has been affected by upward seepage of saline water during High Tide events, denoting the axial lowering of land mass. The salinity intrusion of Ashtamudi Lake in island has become recurrent phenomena in the region resulting in several environmental issues. The island is on the verge of sinking and settlement is rapid with time. The foundation on the site has settled and few residents have abandoned their dwelling units. This desk study and walk over survey analyses the geological processes, their risk and damage perceived in past few years. It attempts to improve understanding of changes in island, causes and implications, with comparison to reported land subsidence worldwide. This paper deals with the settlement issues observed at the site. Some recommendations are proposed in the paper to overcome and manage the existing issues and difficulties in the island