The coastline of Pakistan extends 1,050 km (650 mi), 250 km
falling in Sind province and 800 km in Balochistan. It borders the
productive NE Arabian Sea famous for its upwelling phenomenon. Its
Exclusive Economic Zone (EEZ) covers an area of 196,600 sq.km. and
the territorial waters cover an area of 24,000 km2. The continental
shelf of the Sindh coast extends to a distance of 150 km whereas
that of Balochistan only measures 15-40 km. The prevailing ocean
current direction is clockwise during the southwest monsoon season
and anti-clockwise during the northeast monsoon season. The
salinity value is generally 36 ppt. Tides are neither very high nor
very low, but intermediate; the mean average height is about 10-11
feet. Tides are higher on the eastern side and their velocity is
generally between 1-2 knots but may increase to 4 knots in narrow
creeks.
The Makran Coast Range forms a narrow strip of mountains along
about 75 percent of the total coast length, or about 800 km (500
mi). These steep mountains rise to an elevation of up to 1,500 m
(5,000 ft). Most of the coast is underdeveloped, with deserted
beaches and only a few fishing villages.
The coast is rugged and tectonic in origin as evidenced by the
uplifted terraces, headlands and fluted beds. The mud volcanoes
present along the shores further support this. The coastline is
mostly bare desert with unique landforms such as sandy beaches, mud
flats, rocky cliffs, headlands, bays, deltas, etc. Brief
descriptions of these are given in the following section.
Habitat Types along Pakistan's Coastline:
Beaches
Sandy beaches are common along Balochistan's shores but rare in
Sindh. Well-known beaches in Pakistan include Somniani, Hingol
River, Ormara, Pasni, and Gawadar in Balochistan, and Clifton and
Hawks Bay in Sindh.
Cliffs and Headlands
Rocky shores and cliffs are prevalent in Balochistan. They are
generally composed of conglomerates of soft mudstone and sandstone,
which are highly susceptible to erosion. Headlands are prominent in
Jiwani, Pisukan, Gawadar Rasjaddi and Ormara, and are intervened by
low-lying places comprised of alluvial deposits. Irregular cliffs
present at Ras Malan are a result of tectonic activity. Several
deep-seated faults are also evident. The Sindh coast on the other
hand, is very poor in rocky shores. Buleji, Manora Rocky Ledge,
Cape Monze, and a few other small sites are present in the extreme
western part of the province. The steep cliffs at Cape Monze are a
trajectory of Mor and Kirthar Ranges, and are composed of hard
limestone.
Bays and lagoons
Bays and lagoons are protected bodies of water surrounded by
land having an opening into the sea. In bays, the opening is wide,
whereas in lagoons it is very narrow. There are no bays or lagoons
along the Sindh coast, but several along the Balochistan coast,
such as Gawadar Bay, Ormara Bay and Somniani Bay. Sandy coasts in a
curvilinear pattern fringe the first three mentioned bays, which
are slowly being destroyed by erosion. There are only two lagoons
in the country, both of which are also located in Balochistan.
These are the lagoons of Kalmat Khor and Miani Hor, which harbor
dense mangrove vegetation on the insides.
Mud Flats
Mud flats are gently sloping, unconsolidated inter-tidal parts
of estuaries, and are always occupied by marsh vegetation. Tidal
flats are the same except that they lack vegetation. The entire
Indus Delta and most of the Sindh coast is comprised of mud flats
with mangrove vegetation. Mud flats are nonexistent in Balochistan
except in Gawadar Bay, Kalmat Khor and Miani Hor lagoons.
Mud Volcanoes
Mud volcanoes are conical hills or mountains with a crater on
top through which they gently emit liquid, mud and gas. They are
commonly associated with petroleum deposits, hence their presence
indicates high petroleum potential along the Makran coast. Mud
volcanoes generally emit muddy and saline water, but occasionally
large masses of rock are violently blown hundreds of feet into the
air. The gases that are discharged include methane, ethane and
traces of unsaturated hydrocarbons. Mud volcanoes are a common
occurrence in Balochistan but are not found in Sindh.
Estuaries
Estuaries are coastal embankments that receive substantial
freshwater runoff from land, and experience open tidal circulation
with the ocean. In other words, estuaries are the mouths of rivers
opening into the sea. There are three major estuaries in Pakistan,
the largest one being the Indus estuary on the Sindh coast. The
other two are the Hingol and Dasht estuaries both located in
Balochistan.
Deltas
Deltas are an accumulation of sediments at the mouths of rivers
where they empty into basins. Deltas consist of three major parts:
the delta plain, delta front and prodelta. There are several small
deltas at the mouths of seasonal rivers in Balochistan. However,
one of the largest deltas in the world, the Indus Delta, is located
at the mouth of the Indus River and covers almost the entire coast
of Sindh. It forms a remarkably uniform landform with large
extensive mud flats being intervened by narrow creeks, which are
remnants of old, Indus tributaries. The western part of the delta
between Phitti Creek and Karachi Harbor is now abandoned, although
at one time the Indus River used to flow close to Karachi.