Mapping, inventory and change detection of wetlands of Tavanur grama panchayath

Abstract

A wetland is a distinct ecosystem that is flooded by water (Keddy, 2010). It is distinguished by the characteristic aquatic vegetation (Ramsar convention, 2010). Wetlands Play a critical role in climate change, biodiversity, hydrology and human well-being (Ramsar, 2001). Worldwide, wetlands are in peril now. Wetlands are either being polluted, drained or filled for development also wetlands are being destroyed and LULC pattern altered. Wetland classification maps, inventory and spatio-temporal change information is very important for ecological protection and local government decisions. Use of high resolution remote sensing data along with GIS and GPS is very effective for mapping and change detection of wetlands. No proper documentation on wetland mapping, its inventory, change detection and water dynamics of Tavanur Panchayat. Hence the study was undertaken. LULC mapping and change dynamics between 2008 and 2018 were done by supervised classification and visual interpretation technique. The accuracy of mapping checked by Confusion matrix (error matrix) and Change detection analysis was carried out by PCC method Wetlands of Tavanur Panchayath in 2008 and 2018 were classified and mapped by visual interpretation technique also the water dynamics of Tavanur Panchayath were studied by analysing Depth to water table, Water table contour map, Water table fluctuation map and areal extend of surface water body. The percentage change in land use was found highest for aquaculture (100%) followed by fallow land (56.06%) and paddy converted to coconut (-36.15%). Paddy land experienced the highest transition among the different LULC classes. No appreciable transition was found in the case of river, pond, road and well. Thavanur kayal, Ayankalam kayal, Maravancheri kayal, Varo kayal, Ayankalam aqua culture, Mathur aquaculture and some farm ponds are the main wetlands of Tavanur Panchayath. Marshy type is the common type of wetland in Thavanur other than Aquaculture pond and river. Total area of wetland was estimated 414.17 ha (16.37 %) in 2008 and 409.52 ha (16.87 %) in 2018, it decreased by 4.65 ha only. By studying the water table fluctuation of this Panchayath Kadakassery north , Vallancheri kadavu and Kanjirakutty areas were the most vulnerable areas with a water table fluctuation of 4.92 - 5.44m and Athallur and Kadakassery (centre)regions were less xii vulnerable with fluctuation of 0.08-1.31m only. The area of surface water body increased from 112.97 ha to 192.83 ha during 2008-2013 and from 192.83 ha to 212.92 ha during 2013- 2018. For mapping wetlands of Tavanur Panchayat, visual interpretation technique was found more accurate than supervised classification. The study found that there were not much conspicuous changes in the land use pattern of Tavanur Panchayat during the last decade. Wetlands were found slowly disappearing in Tavanur. Hence an urgent need to make aware of the importance and preservation of these wetlands to prevent further degradation. The analysis of water dynamics showed that water is available for cultivation in the area except in the month of March and April