Spatial changes of estuary in Ernakulam district, Southern India for last seven decades, using multi-temporal satellite data

•Spatio-temporal Changes of a prominent Ramsar Wetland of South India were studied.•Toposheets and satellite imageries spanning a few decades were used for the study.•Visual interpretation and digitization is most apt for this mixed wetland system.•Industrialisation, urban sprawl and avoidable encroachments devour the wetlands.•Urgently required management options for the sustenance of the wetland is proposed.

The study area, located in the western side of Kerala State, South India, is a part of Vembanad-Kol wetlands – the largest estuary in India's western coastal wetland system and one of the Ramsar Sites of Kerala. Major portion of this estuary comes under the Ernakulam district which includes the Cochin City – the business and Industrial hub of Kerala, which has seen fast urbanization since independence (1947). Recently, this region is subjected to a characteristic fast urban sprawl, whereas, the estuarine zone is subjected to tremendous land use/land cover changes (LULC). Periodic monitoring of the estuary is essential for the formulation of viable management options for the sustainable utilization of this vital environmental resource. Remote sensing coupled with GIS applications has proved to be a useful tool in monitoring wetland changes. In the present study, the changes this estuarine region have undergone from 1944 to 2009 have been monitored with the help of multi-temporal satellite data. Estuarine areas were mapped with the help of Landsat MSS (1973), Landsat ETM (1990) and IRS LISS-III (1998 and 2009) using visual interpretation and digitization techniques in ArcGIS 9.3 Environment. The study shows a progressive decrease in the estuarine area, the reasons of which are identified chronologically.