Shitalakshya River is a distributary of the Brahmaputra. In its initial stages it flows in a southwest direction and then east of the city of Narayanganj in central Bangladesh until it merges with the Dhaleswari near Kalagachhiya. A portion of its upper course is known as Banar River. The river is about 110km long and at it widest, near Narayanganj, it is 300m across. Its flow, measured at Demra, has reached 2600cuft/s. It remains navigable year round. The river flows through Gazipur district forming its border with Narsingdi for some distance and then through Narayanganj District.The river's maximum depth is 70ft and average depth is 33ft.Change in course of riversThe Shitalakhya is a branch of the Brahmaputra which has changed its course at least twice in the Bangladesh region in the fairly recent past, indirectly affecting the flow of water in the Shitalakhya. In the 21st century, the main flow of the Brahmaputra waters is through the Jamuna channel. Earlier, after tracing a curve round the Garo Hills on the west, it took a sharp turn in the south-east direction near Dewanganj, and then passing by Jamalpur and Mymensingh, threw off the Shitalakhya branch and flowed through the eastern part of Dhaka district and fell into the Dhaleshwari. The Shitalakhya ran almost parallel to the Brahmaputra and after passing by Narayanganj joined the Dhaleswari. The course of the Brahmaputra through Dhaka district was deserted by the 18th century when it flowed further east and joined the Meghna near Bhairab. Towards the end of the 18th century the Jamuna channel increased its importance and around 1850 it became the main channel of the Brahmaputra.