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Vulnerability assessment of Bangaram Atoll of Lakshadweep Archipelago to environmental impacts: Issues and Challenges

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Disaster Management: Issues and Challenges
Edited by Mrs. B. Eswari, Dr. Yasodharan Suresh and Rajib Bhaduri
Published by Semmodhani Pathippagam A3, abhirami Nivas, no.43 Valmiki Street East Tambaram
Chennai 600059 (ISBN 978-93-81006-75-7 ) (2014) pp: 283-291.
ISBN: 978-93-81006-75-7
VULNERABILITY ASSESSMENT OF BANGARAM ATOLL OF
LAKSHADWEEP ARCHIPELAGO TO ENVIRONMENTAL IMPACTS
Hidayathulla R.M. and Harilal C.C.
Division of Environmental Sciences, Department of Botany, University of Calicut,
Malappuram District, Kerala 673 635
Corresponding author: hidhuakader@gmail.com; ccharilal22@gmail.com
ABSTRACT
Lakshadweep is the tiniest Union Territory of India. This island group, located in the Arabian
Sea, is scattered between 8° and 12° 13’ North latitudes and 71° - 74° East longitudes. This
archipelago consists of 27 islands (10 inhabited and 17 uninhabited), 3 coral reefs and 6
submerged sandbanks. The islands altogether cover an area of 32 sq. km.
The Bangaram atoll lie between 10°45’ and 11°0’North latitudes and 72°15’ and 72°30’East
longitudes. It has an extensive lagoon (46.25 sq. km in size), in which falls two islands
(Bangaram and Thinnakara) and three islets north east of Thinnakara (Parali I, II and II).
These islands and islets, though protected by the atoll are seemed to have been subjected to
natural pressures over decades, resulting in drastic erosion and inundation.
In the present study, an attempt has been carried out assess the extent of changes associated
with the islands falling in Bangaram atoll. A base map of the island for the year 1968 has
been prepared from SoI toposheet using ArcGis (10.1). Similarly Digital Globe satellite
image of Bangaram atoll for the year 2011 has also been obtained and thematic maps were
prepared. The area and extent of land confining to the islands and islets of Bangaram atoll
were then worked out for the years 1968 and 2011and were then compared to assess the
extent of changes associated with these islands for a period of more than 4 decades.
Results of the present study indicated that the islands and islets falling in Bangaram atoll has
been subjected to erosion and thereby decrease in their aerial extent over a period of four
decades. Parli I, which occupied an area of 3.31Ha in 1968, has been subjected to complete
erosion (100%) followed by inundation. Apart from Parli I, percentage change in the extent
of islands / islets were higher with Parli II (65.51%) followed by Bangaram (9.66%), Parli III
(1.39%) and Thinnakkara (0.44%) respectively. The results are indicative of the urgent
management measures to be adopted for the conservation of these island systems.
INTRODUCTION
Lakshadweep is an island group located in the Arabian Sea. It is scattered between 8° and 12°
13’ North latitudes and 71° - 74° East longitudes. The islands of Lakshadweep are
geographically isolated and segregated at 200 to 500 Kms away from the coastal city of
Cochin in Kerala. This archipelago consists of 27 islands (10 inhabited and 17 uninhabited), 3
coral reefs and 6 submerged sandbanks. The inhabited islands include Agathi, Amini,
Androth, Bitra, Chethlat, Kadmath, Kalpeni, Kavaratti, Kiltan and Minicoy. Uninhabited
islands include Viringli, Cheriyam, Kodithala, Tilakkam (i, ii and iii) Pitti (i and ii),
Bangaram, Thinnakara, Parali (i, ii and iii), Kalpitti, Suheli (Valiyakara and Cheriyakara) and
Pitti (Bird Island). The islands, both inhabited and uninhabited, cover an area of 32 sq. km.
Except for Androth, which is the biggest island, all the islands have a lagoon. Bitra is
the smallest island with a large and magnificent lagoon. Among the uninhabited islands,
Suheli is a coconut growing and fishing centre. Pitti or the bird island is a small reef with a
sand bank visited by thousands of birds for nesting. It is designated as a bird sanctuary. The
islands range in area from one ha. to nearly 440 ha. The oceanic islands have a continental
shelf of about 4336 sq.km, the lagoon area of about 4200 sq.km, territorial area of 20,000
sq.km and the EEZ of 4,00,000 sq.km accounting for 20% of the Indian EEZ. Lakshadweep
is one of the world's most spectacular tropical island ecosystems.
The marine ecosystems of Lakshadweep are extremely diverse, attributed to
geomorphologic and climatic variations along the coast. The precious heritage of ecology and
culture is supported by the extremely fragile ecosystems. The major components are the coral
reefs, lagoons, seagrasses, seaweeds, algae and mangroves. These delicate ecosystems are
inhabited by a wide variety of fishes, turtles, octopus, crabs, molluscs, sponges, echinoderms,
other invertebrates, reptiles, dolphins and whales. Common Sea birds are Tarataihi (Sterna
fuscata) and Karifetu (Anous folidus) the former being the state bird. Most of the birds nest
on an Island called Pitty- a bird Sanctuary. The flora of Lakshadweep is also diverse.
Coconut is the only commercial crop.
The islands and the reefs support the livelihood of people, providing food, income,
employment, shelter and protection. However, the economic development of the islands over
the years brought in its wake, several anthropogenic vulnerabilities to the islands. It is evident
from various studies that the coastal environments confining to the islands of Lakshadweep
archipelago has been subjected to pressures of varied type and coastal erosion is the prime
among them. The extent of coastal erosion in most of the inhabited islands of Lakshadweep
has either been assessed or undergoing assessment. However studies are limited in the area of
coastal erosion associated with uninhabited islands. Due to lack of such scientific studies,
there was little attention on the coastal environments of such uninhabited islands, which are
facing several environmental issues. The present study has been carried out to assess the
extent of coastal erosion and thereby geomorphological changes associated with the islands
of Bangaram atoll like Bangaram, Tinnakkara and and Parli (Parli I, II and III islets).
Study Area
Bangaram atoll is located in the Arabian Sea, about 459 kms away from Cochin,
Kerala. The atoll lie between 10°45’ and 11°0’North latitudes and 72°15’ and 72°30’East
longitudes. It has an extensive lagoon (46.25 sq. km in size), in which falls Bangaram and
Thinnakara islands and three islets north east of Thinnakara, ie. Parali I, II and II, as depicted
in plate 1. These islands and islets, though protected by the atoll are seemed to have been
subjected to natural pressures over decades, resulting in drastic erosion and inundation. The
gravity of the environmental issues associated with these islands have also been increased
due to tourism and other allied activities.
Plate 1. Imagery of Bangaram atoll
MATERIALS AND METHODS
In the present study, an attempt has been carried out to assess the shoreline changes and
changes in the extent of area associated with the islands falling in Bangaram atoll over a
period of 43 years. Base maps of the islands for the year 1968 have been prepared from SoI
toposheet no. 49B/5 using ArcGis (10.1). Similarly Digital Globe satellite images of the
islands falling in the atoll for the year 2011 has also been obtained and thematic maps are
prepared. The extent of land area confining to the islands and islets of Bangaram atoll are
then worked out for the years 1968 and 2011and are then compared to assess the magnitude
of changes over a period of more than 4 decades. All data used in this study are geo-
referenced using the ground control points and real world coordinates collected from Google
Earth. The spheroid used was World Geodetic System 1984 (WGS84).
RESULTS AND DISCUSSION
The present study has been carried out to assess the shoreline changes and changes in the
extent of area associated with the islands falling in Bangaram atoll over a period of more than
four decades. For fulfilling this objective, the shorelines of all islands / islets falling in
Bangaram atoll for the years 1968 and 2011are vectorised on screen considering the
vegetation lines as shoreline. The maps so produced for the atoll for the years 1968 and 2011
are depicted in plates 2 and 3 respectively. The areas of each islands / islets were calculated
separately for the years 1968 and 2011along with the percentage change in land area and are
depicted in Table 1. Field level observations and GPS surveys were carried out to assess the
veracity of information contained in the primary data.
Plate 2. Shoreline map of the atoll for the year 1968
Plate 3. Shoreline map of the atoll (2011)
Table 1 . Changes in the extent of islands falling in Bangaram atoll
Island / Islet
Year
Total area
(Ha)
Percentage of
change
Nature of
change
Bangaram
1968
64.45
9.66%
Decrease
2011
58.24
Thinnakara
1968
46.41
0.44%
Decrease
2011
46.21
Parali I
1968
3.32
100%
Decrease
2011
0
(Washed out )
Parali II
1968
2.87
65.51%
Decrease
2011
.99
Parali III
1968
3.61
1.39%
Decrease
2011
3.56
Being oceanic, small, geographically isolated and exposed, environmental
disturbances associated with the island are many. Such disturbances are mostly from storms,
cyclones and heavy rains. The low lying nature of islands makes them vulnerable to sea level
rise due to potential global warming and climate change. The islands frequently face the risk
of inundation of sea water due to tidal and wave actions attributed by storm surges.
Lakshadweep is influenced by south-west monsoon winds. During southwest
monsoon, the maximum height of waves is 5m and in non-monsoon season, it falls to about
1.4 m. Data from the Meteorological Department indicate mean wind speed in Lakshadweep
in May-September ranging between 6.10 - 9.25 knots in Minicoy and 7.35 - 12.54 knots in
Amini. Average annual rain fall is about 1640 mm (Minicoy) and 1504mm (Amini).
A few of the cyclonic depressions and storms which occur in the south Arabian Sea
during April to June affect the weather over territory every year. Thunderstorms mostly
occur in the months of April to June and October and November. Apart from these, there are
outbreaks of major storms and cyclones in the Islands. Such major incidents in the form of
calamities are reported in 1847, 1891, 1922, 1963, 1977, 2004 and 2011. Apart from direct
damages to vegetation and property, the hitting of waves during such occasions results in
drastic coastal erosion and degradation. Reports state that the UT of Lakshadweep has been
subjected to more than 27 such major events during last 115 years, ending in 2011.
Along with natural disasters, the islands of Lakshadweep are recently been subjected
to several anthropogenic pressures, which are adversely affecting its ecology. The main
attribute in this category is tourism. Apart from tourism, Lakshadweep is on the trade route
between Africa, Arabia and west coast of India (Malabar). There has been a dramatic increase
in passenger and cargo traffic in recent times. Since major vessels could not enter shallow
lagoons, passengers are being transported through small mechanized boats. Studies proved
that the use of such facilities epitomized the degradation of island ecosystem.
In addition to tourism and transportation, other activities like dredging of navigational
channels, unsustainable fishing practices, coastal development and souvenir collection had
resulted in the quality of environment pertaining to the island. Such activities together with
coral mining have resulted in severe impacts on the ecology of the coral environments of the
island (Ajaya Kumar, et al., 1989; Banidhar, et al., 2005; Anu, et al., 2007; Muralidharan and
Praveen Kumar, 2001; National Task Force, 2005).
Results of the present study is also indicative that the islands / islets falling in Bangaram atoll
have been subjected to erosion and thereby decrease in their aerial extent over a period of
four decades. Parli I, which occupied an area of 3.31Ha in 1968, has been subjected to
complete erosion (100%) followed by inundation. Apart from Parli I, percentage change in
the extent of islands / islets were higher with Parli II (65.51%) followed by Bangaram
(9.66%), Parli III (1.39%) and Thinnakkara (0.44%) respectively.
Though the islands/ islets are falling in the same atoll, the magnitude of changes associated
with them varied considerably, which is evident from their percentage change in extent from
0.44% to 100%. This is indicative of the diversity in the nature and magnitude of geological
processes associated with these islands / islets. The changes in the pattern of waves, tides,
currents etc., brought about by changing geological and environmental conditions might have
attributed to the shoreline erosion and thereby decrease in the extent of landed areas. Also it
can be inferred that the changes in the geological processes like erosion / accretion associated
with these islands / islets have also differed considerably owing to their relative position,
shape and proximity to the reef, resulting in the differences in their aerial extent. However
total erosion and inundation of Parli I, an islet of the atoll has to be looked at a different
perspective as it is an indicative of drastic coastal erosion associated with the islands / islets
falling in the atoll. Also the results are indicative of the urgent management measures to be
adopted for the conservation and management of these island groups.
SUMMARY AND CONCLUSION
Lakshadweep is an island group located in the Arabian Sea. Bangaram atoll is part of
Lakshadweep group of islands and is uninhabited. The natural disasters associated with the
islands group are many. Coastal erosion and thereby decrease in the extent of landmass is one
among the major disasters associated with the island.
In the present study, an attempt has been carried out to assess the extent of coastal erosion
and thereby changes in the extent of landmass associated with the islands like Bangaram and
Thinnakara and islets like Parli 1, 2 and 3 of Bangaram atoll. A base map of the island for the
year 1968 has been prepared from SoI toposheet using ArcGis (10.1). Similarly Digital Globe
satellite image of Bangaram atoll for the year 2011 has also been obtained and thematic maps
were prepared. The area and extent of land confining to the islands and islets of Bangaram
atoll were then worked out for the years 1968 and 2011and were then compared to assess the
extent of changes associated with these islands for a period of more than 4 decades.
Results of the present study indicated that the islands and islets falling in Bangaram atoll has
been subjected to erosion and thereby decrease in their aerial extent over a period of four
decades. Parli I, which occupied an area of 3.31Ha in 1968, has been subjected to complete
erosion (100%) followed by inundation. Apart from Parli I, percentage change in the extent
of islands / islets were higher with Parli II (65.51%) followed by Bangaram (9.66%), Parli III
(1.39%) and Thinnakkara (0.44%) respectively. The results are indicative of the urgent
management measures to be adopted for the conservation of these island systems.
REFERENCES
Ajay Kumar Varma R., Unnikrishnan K. R. , Ramachandran K. K. (1989), “ Geophysical and
hydrogeochemical studies for the assessment of groundwater potential in the Union Territory
of Lakshadweep, India, Centre for Earth Science Studies, Trivandrum.
Anu, G., Kumar, N.C., Jayalaxmi, K.V. and Nair, S. M., (2007). Monitoring heavy metal
portioning in reef corals of Lakshadweep Archipelago, Indian Ocean, Environmental
monitoring assessment”, Vol. Nos. 1-3, pp: 195 208.
Benidhar Deshmukh, Anjali Bahuguna, Shailesh Nayak, V. K. Dhargalkar and T.G. Jagtap
(2005). “ Eco- geomorphological zonation of Bangaram Reef , Lakshaweep”, Journal of the
Indian Society of Remote sensing, Vol. 33, No.1.
Muralidharan, M.P. and Praveen Kumar (2001) , “ Geology and geomorphology of Kavaratti
Island ,UT of Lakshadweep” Geological Survey of India special publication, No.56, pp: 9-
13.
National Task Force (2005) “A Special Study of Lakshadweep Islands to assess Vulnerability
to Various Hazards and suggest Mitigation / Prevention Measures”. A project report.
***
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This paper focuses on the partitioning of trace metals in five selected coral species from Lakshadweep Archipelago, which remains as one of the least studied areas in the Indian Ocean. Based on the morphological features, selected coral species are classified as massive (Porites andrewsi), ramose or branching (Lobophyllia corymbosa, Acropora formosa and Psammocora contigua) and foliaceous (Montipora digitata). Relating trace metal concentrations with morphological features in skeleton, highest concentrations of all the trace metals (except Zn) were reported for the ramose type corals. In tissue, all the metals (essential as well as non essential) showed highest concentrations within the branching type corals. Irrespective of their growth characteristics/pattern, all species except P. contigua displayed higher concentrations of Pb, Ni, Mn and Cd within their skeleton compared to tissue which may exemplify a regulatory mechanism to avoid the build up of the concentrations of these metals in their bio-part, strikingly toxic metals like Cd and Pb. The concentrations of trace metals in the skeleton and tissues of these coral species were subjected to 3 way ANOVA based on non standardized original data and the results showed significant differences between metals and between species leading to high skeleton/ tissue -- species interaction as well as skeleton/tissue – metal interaction. The significant values of student's t calculated are depicted in the form of Trellis diagrams.
Geophysical and hydrogeochemical studies for the assessment of groundwater potential in the Union Territory of Lakshadweep
  • Ajay Kumar Varma
  • R Unnikrishnan
  • K R Ramachandran
Ajay Kumar Varma R., Unnikrishnan K. R., Ramachandran K. K. (1989), " Geophysical and hydrogeochemical studies for the assessment of groundwater potential in the Union Territory of Lakshadweep, India", Centre for Earth Science Studies, Trivandrum.
Geology and geomorphology of Kavaratti Island
  • M P Muralidharan
  • Praveen Kumar
Muralidharan, M.P. and Praveen Kumar (2001), " Geology and geomorphology of Kavaratti Island,UT of Lakshadweep" Geological Survey of India special publication, No.56, pp: 9-13.