The Gorai is a very old river. Its early name was Gauri. The famous geographer and astronomer Ptolemy noticed about five estuarine mouths of the Ganges. One of those, the 'Kambari Khan', was perhaps the Gorai. The course of the Gorai- is wide, long and meandering. From its originating point at Kamarkhali, it is navigable by boats in the monsoon, but in the dry season it becomes non-navigable. In the downstream it is navigable throughout the year. Maximum recorded flow at Kamarkhali is 7,932 cumec. The breadth of the river increases as it flows down and at the end it is about 3 km.
The Gorai is one of the longest rivers in Bangladesh and its basin is also very wide and extensive. It flows through Kushtia, Jessore, Faridpur, Khulna, Pirojpur and Barguna districts. Agriculture and irrigation in these areas are very much dependent on the Gorai-Madhumati. Kumarkhali, Janipur, Sheuria, Ganeshpur, Khulumbari, Langalbandh, Shachilapur, Nacole, Lohagara, Pangsha, Baliakandi, Boalmari, Kashiani, Bhatiapara, Nazirpur, Kachua, Pirojpur, Sarankhola, Mathb
aria, Patharghata and Morrelganj are the important places on the banks of the Gorai.
The Gorai takes off from the Ganges at Calabria, north of kushtia town and 19 km downstream from hardinge bridge. South of Kushtia its first offshoot, the Kaliganga branches off to join the kumar near shailkupa. This river has been dammed by one of the primary canals of the ganges-kobadak irrigation project (G-K Project) and the lower half of the course is now almost a dry bed. The main river bifurcates and rejoins several times as it flows southeast to Mohammadpur Upazila in Magura district. From here it changes its name to Madhumati. The Kumar, the nabaganga and the Chitra join it through several channels south of Mollahat Upazila. There it changes its name to Baleshwar, which in turn changes to Haringhata from the Bog forest outpost of the Sundarbans. The Gorai-Madhumati has a flood discharge of nearly 7,000 cumec but in winter its flow goes down to five cumec.
All the rivers between the Khulna-Ichamati, Ganges, Gorai-Madhumati and the bay of Bengal are connected by cross-channels, which are especially numerous in the Sundarbans. They are of great importance for inland navigation in the delta.