Management of Coral Reefs in Gulf of Mannar using Remote Sensing and GIS Techniques with Reference to Coastal Geomorphology and Land Use Fluvio-Marine Landforms Deltaic plain Deltaic plains are predominantly controlled by fluvial processes. In the study area deltaic plain is considered to be of Pleistocene to Recent age (Loveson 1993). The areas around the river courses of Vaippar, Gundar, Palar and Kottakkarai Rivers, had vast deltas, but at present they are found to be inactive. The deltaic plains are marked by flat and vast areas, having vegetation cover. Number of tanks has been noticed on the deltaic plains. The total area has been estimated to be about 221.69 kmē. Fluvial Landforms Flood plain Well-established rivers usually have their floors covered with alluvium, in which the normal flow channel is covered. The surface of low relief on the alluvium from the banks of the low-water channel to the base of the valley walls is called the flood plain of a river. Flood plain and their major morphologic subdivisions are primarily deposited landforms. Floodplains have been very clearly observed along the riverbanks of Kallar, Vaippar and Gundar Rivers in study region. These flood plains are inactive, which is covered with thick vegetation. The total estimated area of flood plain in study region is 24.43 kmē. Natural levee Land forms in deltaic regions include natural levees bordering river channel and backed by lowering of the swamp or flooded depression in the lower parts of the river valleys (Bird 1984).The over bank deposits are located more or less parallel to the riverbank. Generally, the levees are mainly seen adjoining the meandering course of the rivers. A natural levee has been observed in the Gundar River basin. The width of these levees encountered ranges from 2 to 3 km. and covers an area of 1.10 kmē. Flood basin Flood basin occupying the shallow reaches of the flood plain consists of mostly gray brown sandy and silty clay and clay. Kottakkarai River surface has a flood basin with an area of 26.83 kmē. Aeolian Landforms Sand dune complex Almost entire coastal plains in the study area are covered by sand dune (Figure 4). The area in between swale system and shoreline is marked by dune complex. The area covered by dune complex has been estimated to be about 469.10 kmē. However, extensive spread is observed around Rameswaram Island, Mandapam, Mangudi, Bharathinagar, Valinokkam, Thunamariyur, Terku Nerippaiyur and Tuticorin areas. In other places the areal spread is less. Numereous dunes have been observed the places like Tuticorin, Taruvaikkulam, Sippikkulam, Terku Narippaiyur, Bharathinager near Keellakkarai, Valinokkam, Mandapam and Rameswaram are situated on the dune complex. Aeolian process is dominating in this zone and its intensity can be seen in the migrating dunes in Tuticorin itself. Thruvaikkulam and the other above-mentioned areas also exhibit features similar to those in Tuticorin area.  Figure 4 Sand dunes at south of Rameswaram Island Teri dune complex In the coastal plains between south of Vaippar River and Tuticorin near Maravanmadam seven patches of teri dune complexes have been observed with a thick cover of vegetation. In the area north of Panaiyur, oval shaped teri dunes with sparse vegetation have been observed. The areal extent of this dune has been calculated to be 6.27 kmē. Another two teri dunes have been observed near Kumarapuram. They cover an area of 2.67 kmē. Near Pandiyapuram, rounded dune complex has been observed with thick vegetation. The area of this dune has been estimated to be 4.27 kmē. Near Milavittam small rounded patches of teri dune complex covering an area of 2 kmē has been observed. Two other teri dune complexes have been observed near Maravanmatam area with thick vegetation. They cover an area of 3.08 kmē. All teri dune complexes in this area are trending in the northeast to southeast direction. Biogenic Landform Back swamp Back swamps occur in marshy areas along the coast; they particularly occur at the edge of the tropical or sub-tropical seas, in bays lagoons and estuarine regions (Gerlech 1973). Small back swamp areas have been observed in the areas near the mouth of Korampallam odai around Tuticorin coast and west of Rameswaram Island. They cover a total area of 1.87 kmē. These swamps are covered by mangrove vegetation. |