Its source lies in the Hindukush Mountains, from where it is fed by the glacial waters throughout the year and flows through the Kalam Valley in a narrow gorge with a rushing speed up to Madyan and lower plain areas of Swat Valley up to Chakdara for 160 km. In the extreme south of the valley, the river enters to a narrow gorge and joins the Panjkora River, at Qalangi, and finally empties into Kabul River, near Charsadda. It is diverted near Batkhela for irrigation and power generation purposes.