The island as seen from the sky

Salcette Island is a large island off the coast of Maharashtra, India in the Arabian Sea. The metropolis of Mumbai (formerly Bombay), and the city of Thane lies on this island.

Location

The island is located at the mouth of River Ulhas, which empties out at the northeast region of the island. The river empties out into two creeks, the Thane Creek which forms the eastern seaboard and the Vasai Creek, which forms the northern seaboard. Both creeks empty out into the Arabian Sea. The coordinates are approximately 20° N and 72° E. The city district, Mumbai surbuban district and part of Thane district are the Maharashtra districts to occupy this island. The capitals of the latter two are also on this island.

History

The actual island today is much larger than it originally was. Before 1782, the area was an archipelago consisting of many isles. Salcette Island was one of them. The islands were part of the kingdom of Ashoka and then various Hindu rulers of the Silhara dynasty until 1343, when it was annexed by the kingdom of Gujerat.

In 1534 the Portuguese took the islands from Bahadur Shah of Gujarat. The islets remained in their hands until 1661, when it ceded as the dowry of Catherine de Braganza to Charles II of England. He, in turn leased it to the British East India Company in 1668 for £10 per annum. The company found the deep harbour at Bombay eminently apposite, and the population rose from 10,000 in 1661 to 60,000 by 1675. In 1687, the East India Company transferred their headquarters there from Surat.

In 1784, the Hornby Vellard was the first of the engineering projects aimed at amalgamating the isles. The isles were hilly and the waters between them were shallow. William Hornby, then Governor of Bombay, initiated the project in 1782 despite opposition from the directors of the East India Company. The cost of the vellard was estimated at Rs. 100,000.

From 1817 the city was reshaped with large civil engineering projects merging the islands into one single mass of around 435 km² by 1845. This was done by razing the hills and using the debris to fill the shallows.

Seven islands of Bombay (Mahim, Bombay, Mazagaon, Parel, Colaba, Little Colaba (Old Woman's Island) & Sion) were merged to form Old Bombay. This land body was then merged with the northern islands of Salcette and Trombay to form a monolithic island which was christened Salcette Island. The area north of Old Bombay formed the region of Greater Bombay. The southern part of the island is a peninsula.

Geography

The island is still hilly in many places. The highest point on the island is around 450 m. in the Borivali National Park in the northern reaches of the island. The park is the world's only National Park to be accommodated within city limits.

Geology

The island is located at the confluence of a number of fault lines. This makes the area earthquake prone, up to a magnitude of 6. The island is mostly composed of black basalt rock. Since it is along the sea coast, it also has a sandy belt on its western coast. The southern region of Old Bombay is mostly at sea level. However, the parts which were erstwhile shallows are below sea level. Many parts of the city are hilly.

Other Natural formations

Lakes

There are three major lakes on the island Powai Lake, Tulsi Lake and Vihar Lake. The latter two lakes supply part of the city's water requirements. Numerous other smaller ponds and lakes are also present in the Thane region.

Rivers

There are three rivers on this island, over the years these rivers have been reduced to a brook. The Mithi (Mahim) River, Oshiwara River and Dahisar River empty out into the Arabian Sea. Mithi River originates from the Powai Lake.

Creeks

The coast of the island is inundated by numerous saline creeks. The Mahim creek separates the city from the suburbs in the west, and the Sion Creek in the east. Further north on the western coast, the Oshiwara river empties into the Malad (or Marvé) Creek and the Dahisar River into the Gorai Creek. The eastern waterfront too, has many small creeks.

Wetlands

The small southern part of the eastern waterfront of the island forms the Bombay harbour. North of this region lie vast amounts of protected wetlands, home to migratory birds. The northern, north western part of the island and parts of Mahim River also have government protected marshlands. These swampy regions form massive and dense mangrove forests.

Bays

The western coast has numerous bays. The most well known is Back Bay, of which Marine Drive is a part of. Other well known bays are Mahim Bay and Worli Bay.