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IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002 
REMOTE SENSING AND GIS TECHNIQUES FOR MAPPING COASTAL 
GEOMORPHOLOGY IN GULF OF MANNAR, SOUTHWEST COAST OF BAY O 
BENGAL 
M. Thanikachalam and S. Ramachandran 
Institute for Ocean Management, Anna University, Chennai-600 025, India 
aisuwariyaa @yahoo.com, ramachandran sun hotmail.com 
KEY WORDS: Remote Sensing, GIS, Coastal Geomorphology, Coastal Landforms, Coral reef, Beach Ridges and Spit 
ABSTRACT: 
Coastal geomorphology map could help in various coastal zone management planning. Coastal geomorphology map of Gulf of 
Mannar form Dhanushkodi to Tuticorin was prepared data on 1: 50,000 scale using IRS LISS-III satellite data and Survey of India 
(SOI) topographic sheets and validated by ground truth. Various coastal landform units have been identified and delineated based on 
the remote sensing data. The landforms are grouped in to marine, fluvio-marine, fluvial, aeolian and biogenic landforms. Most of the 
landform units such as spits, beach ridges, beaches, strand line, back swamp, mud flat etc indicate that the coast is prograding 
towards the seaward side. 
1. INTRODUCTION 
The coastal geomorphological maps portray the forms of the 
surface, the nature and processes of the surface materials and 
indicate the kind of magnitude of the processes involved. 
Coastal geomorphological mapping allows an improved 
understanding of coastal land use planning, harbor area 
management, coastal resource and coastal zone management 
etc. A detailed coastal geomorphological map is one of the 
principal means of studying morphology, genesis, distribution 
and age of forms, to interpret the geomorphic history of any 
evolved landscape. The synoptic coverage and high precision of 
remotely sensed data, coupled with marked coast-effectiveness 
and time efficiency of the data acquisition and analysis 
procedures have made satellite based coastal gepmorphological 
mapping an extremely effective tool for coastal management in 
the recent time. 
About two thirds of the world’s population lives within 60 km 
of the coastline. This proportion is increasing as people seek 
better standards of living and move away from inland and 
upland. As a result of increasing stress along the coastal area, 
anthropogenic impacts on coastal zone have become severe. 
Coastal resources like coral reef, seaweeds and sea grass and 
mangrove etc. have been degraded due to various 
developmental activities and population pressure. In the state of 
Tamil Nadu, between the year 1988 and 1998, 25.56km? of 
coral reefs and 2.16km? of seaweeds were lost in Gulf of 
Mannar (Thanikachalam and Ramachandran 2002). Between 
the year 1986 and 1993, 0.36km? area of mangrove in 
Pichavaram was lost and nearly 2500km? of the mangrove were 
lost in entire India between 1986 and 1994 (Krishnamoorthy 
391 
1995). Apart from the anthropogenic activities, natural causes 
also play an important roll in coastal environment changes. In 
Gulf of Mannar coast, between the year 1969 and 1998, 4.34 
km? and 23.49kn? of mainland coast and 4.16km? and 3.31km? 
of island coast were eroded and accreted due to the combined 
action of anthropogenic and natural agents (Thanikachalam 
2000). In this present study, coastal landforms and coastal 
geomorphic classification of Gulf of Mannar coast has been 
attempted using remote sensing and GIS techniques. 
2. STUDY AREA 
The study area (Figure 1), Gulf of Mannar, extending from 
Tuticorin to Rameswaram island in the SW-NE direction, lies 
between 78? 5' & 79?30' E longitudes and 847^ & 9915" N 
latitudes, to a length of about 140 km. There are 21 islands, 
situated at an average distance of about 8 km from the coast and 
running almost parallel to the coastline. This area is endowed 
with a combination of ecosystems including , mangroves, 
seagrass, seaweeds and corals reefs. Different types of reef 
formations have also been observed in Gulf of Mannar viz. 
fringing reef, patch reef and coral pinnacles. The coast of Gulf 
of Mannar is mostly underling by Quaternary to Recent 
formation. The west of this coastal area is bound by heavy 
crystalline metamorphic rocks of Pre Cambrian and having 
breath of 10-100 km (Ramasamy 1997). Being a gradient coast 
it has developed well fabricated network of. deltas, backwater, 
creeks, protruding deltas, estuaries, back swamps and coral reef 
etc.