List of rivers of Bangladesh

[5] The number differs widely due to lack of research on the counts and the fact that these rivers change flow in time and season.

There is an including tributaries flow through the country constituting a waterway of total length around 24,145 kilometres (15,003 mi).

Taking the Karatoya as the central dividing water-channel of the district, the other rivers may be classified into the eastern and the Western systems.

Evidences show that the rivers Karatoya and Nagar have changed their courses in the past, while the Jamuna, lying on the eastern boundary of the district, is in fact a new channel of the Brahmaputra.

By the time of Rennell's mapping, this course had been abandoned in favour of a shorter route down what is still called the old Brahmaputra river past Mymensingh.

Later the Ganges drifted to the east and the Padma grew mighty, taking all the drainage of northern and upper Bengal.

The Jamuna, nowhere less than 4 miles wide during rain, runs in the west and the equally important Meghna encloses the district on the east.

They are connected by the old channel of the Brahmaputra running through the centre of the district in a south-easterly direction from above Bahadurabad up to Bhairab Bazar.

In the Sadar subdivision, however, the general slope of the country is from west to east, and the main rivers fall into the Hurasagar, a tributary of the Jamuna.

During the rainy season these moribund rivers act as excellent drainage channels draining off a large volume of water and have a considerable current.

Tangail District is flanked on the west by the mighty river Jamuna, which is nowhere less than 4 miles wide during the rainy season.

The Dhaleshwari, first an old channel of the Ganges and then of the Brahmaputra, cuts across the south-western corner of the district on its powerful sweep to join the Meghna near Narayanganj.

The old Brahmaputra's most important offshoot is the Jhinai; striking off near Jamalpur it rejoins the Jamuna north of Sarishabari, while another branch flows past Gopalpur.

During the last 150 years or so, this diversion of the old Brahmaputra to its present Jamuna channel has considerably prompted the geographers and geologists to enquire deep into it.

With the help of Major James Rennell's maps (1764 to 1773) and of the Revenue Survey it is possible to reconstruct the history of the Bengal Delta and its river systems.

At the end of the 18th century, probably as a result of the great Tista floods in 1787, the Brahmaputra changed its course and joined the Padma at Goulundo.

Whatever might have been the cause, by 1830, the diversion of old Brahmaputra was complete, ushering in a gradual but radical change in the river system of the Tangail district.