Environmental Engineering Reference
In-Depth Information
Physical Features
St. Martin's is located about 9 km south of the Cox's Bazar-Teknaf peninsular tip
and about 8 km west of the northwest coast of Myanmar at the mouth of the river
Naf. The island lies between 92°18
N
latitudes and forms the southernmost part of Bangladesh. It is almost fl at and is
3.6 m above the mean sea level. The island has an area of only about 8 km
2
and is
aligned NNW and SSE. The main island is dumbbell in shape and is divided in fi ve
different physiographic areas—Uttar Para, Golachipa, Madhya Para, Dakhin Para,
and Cheradia (UNDP
2010
).
While within the tropical belt, the weather of the St. Martin's Island is heavily
infl uenced by the subtropical monsoonal climate that prevails over Bangladesh.
Lying in a north-south direction, the island has a wider northern section and a nar-
rower elongated southern section with a constriction between where the sand dunes
of the western and eastern shores have almost joined. This narrow neck is gradually
being eroded from both sides. The site is a sedimentary continental island consisting
of continental base rocks which coral communities have colonised. The base rock is
Girujan Clay shale (Pliocene), and grey to bluish grey inter-bedded with subordinate
sandstone (UNDP
2010
). The soil type of the island consists mainly of alluvial
sands mixed with marine calcareous deposits. The surface water temperature around
St. Martin's ranges between 18 and 31 °C, while coastal water salinity fl uctuates
between 26 and 35 ppt (Tomascik
1997
). The turbidity of inshore water ranges from
1.5 to 8.0 m depending on the sea condition and tide cycle (UNDP
2010
) (Fig .
1
).
′
and 92°21
′
E longitudes and 20°34
′
and 20°39
′
Ecosystem Assortments
Rocky Land Habitat
The rocky land area covers about 1 km
2
and is the last remaining habitat for rare
species such as the water monitor (
Varanus salvator
), Bengal cobra (
Naja kaouthia
),
bush birds, water birds and garden lizards, as well as native herbs, shrubs and climbers
(Kamal
2008
). The rocky ground and shallow water pools provide an excellent
terrestrial microhabitat, especially during winter.
Sand Dunes and Beaches
The main shoreline habitats are sandy beaches and dunes, with the main sediments
being alluvial sands. The sandy beaches of the site are supposedly the best nesting
sites in Bangladesh for globally threatened marine turtles (Kamal
2008
).
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