Kumar River an old river originates from the Mathabhanga river at Hatboalia in Chuadanga district. Rennell depicted this river in his atlas prepared in 1764. The river was not much active at that time. Though the river overflows in monsoon, it turns almost dry in the lean period. The river was locally called as Kalobeel (Black coloured beel).
The Kumar flows southeast from its origin keeping its course parallel to the nabaganga. Near Magura, the river meets with the Nabaganga and the joint flow keeping the name Nabaganga flows further south. Once upon a time, the Kumar received its major flow from the Kaliganga, Chhaku, Hanu, Muchikhali etc on its course. These are all offshoots of the gorai. The origin of the Kumar has been disconnected from the Nabaganga after commissioning of the ganges-kobadak (G-K) irrigation project. As a result, the Kumar is now turned into a narrow channel. The only source of the river is excess water from the G-K project and local rainwater.
Originating from Hatboalia, the Kumar crosses about 25-km course and further advances along the border of Jhenaidaha district. There after it enters Shailkupa upazila and meets with the Nabaganga near Magura district town. The total length of the river is about 144 km.
The total catchment of the Kumar lies inside the G-K project. The river is not navigable, as it has no independent source of its own. Navigation is possible only 3 or 4 months during the monsoon season. In general, the river shows no erosional tendency, but near Faridpur town and Nagarkanda upazila town, it shows a little bank erosion. The river sometimes overflows the lower parts of Shailkupa upazila whenever the rainfall is very high and it damages the crops. The average width of the river from origin to Garaganj is about 107 metres and the later part is about 230 metres. On its total Catchment area, the Kumar follows a meander course.
Alamdanga, Harinakunda, Shailkupa, Sreepur, Magura are some important places on the banks of the Kumar. A little far from Shailkupa upazila, in Manahardi, an ancient mosque was built during the period of Emperor Akbar, and in Kabirpur a remnant of a Nilkuthi still stands on the bank of the river. It is to be mentioned that the river is locally known as the shitalakshya in Nagarkanda town. [Masud Hasan Chowdhury]
See map in ganges-padma river system.