The Surma River rises as Barak on the southern slope of the Naga-Manipur basin. The Barak is divided into two branches within the Cachar district of Assam in India. Surma, Sylhet, the North Branch, flows west and southwest of the city. In addition, Sylhet, the north and west of Sunamganj town, and flows from there to the southwest and then south Madnar where kushiyara, the other branch of the Barak. Receives several rivers and streams south of the plateau of Meghalaya. From east to west Lubha, Hari (Kushi) are Goyain response (Cheng Khal), piyain, Bogapani, Jadukata, and Shomeshwari Kangsar.
The Surma is susceptible to flooding in the monsoon. The flood season is usually from the last week of May to mid-October, the average flow rate during this period about 30,000 CUSEC. Between 1950 and 1958, the maximum and minimum flow CUSEC recorded 53 008 (15 August 1958) and 487 CUSEC (March 21, 1954), respectively. Bifurcates into the Surma Southern Mohanganj, and shortly after receiving the Kangsar and south of the mogra., Is in the western English Channel as Dhanu in its upper reaches, known Baulai in the middle and bottom Ghorautra. It joins the Meghna near Kuliarchar. The southern branch of the Barak, as Kushiyara, Manu gets the northern city of Maulvi Bazar and a channel is divided into North Bibiyana, and one in the south, they took the original name of the river of Barak. The Bibiyana renamed kalni, ajmiriganj under the course and closes near the Surma. The Barak (West) receives khowai and the hills of Tripura and falls into the Surma in Madnar.
The way the rivers change their names really confusing. To make matters worse, there seems no general agreement about the course of the river by a single name, do not identify the entire course of the river various names throughout its history have. The Surma Ajmiriganj is often called the Meghna below. The thing would be easy, but the fact that Madnar down for about 26 km (distance), one of the two channels of the Surma-Meghna is known as dhaleshwari. North Dhaleshwari is switching behavior of the courses. The change takes place south of Austagram, where the two channels and is known as Dhaleshwari. To avoid confusion, the main channel of the Dhanu Ajmiriganj to the confluence-Ghorautra known as Surma. This confluence is located 5 km east of Kuliarchar. Downstream from where the river is known as the Meghna. Most of the system is in the Surma basin Haor, where the derivative is defined clearly. In the Piedmont region to jaintiapur Durgapur, the network of rivers and canals overflow in the rainy season, and large expanses of water that connect with the Haor rivers. In the basin of Haor also loosened the rivers overflow and flood the Haor in the first part of the rainy season and for most of the water as soon as the monsoon rains.
The average depth of the river is 282 feet (86 m) and a maximum depth of 550 feet (170 m).