Sone River of central India is the Second largest of the Ganges' southern tributaries after Yamuna River. It originates near Amarkantak in Madhya Pradesh, just east of the headwater of the Narmada River, and flows north-northwest through Madhya Pradesh state before turning sharply eastward where it encounters the southwest-northeast-Kaimur Range. The Sone parallels the Kaimur hills, flowing east-northeast through Uttar Pradesh, Jharkhand and Bihar states to join the Ganges just west of Patna. Geologically, the lower valley of the Son is an extension of the Narmada Valley, and the Kaimur Range an extension of the Vindhya Range. Dehri on sone and Sonbhadra are the major cities situated on Sone River.
(Source: http://economictimes.indiatimes.com/topic/Dehri-on-Sone accessed on 25.09.2017)
The Sone river (784 km long) is one of the largest rivers of India. Its main tributaries are the Rihand and the North Koel. The Sone has a steep gradient (35–55 cm per km) with quick runoff and ephemeral regimes, becoming a roaring river with the rain-waters in the catchment area but turning quickly into a fordable stream. The Sone, being wide and shallow, leaves disconnected pools of water in the remaining part of the year. The channel of the Sone is very wide (about 5 km at Dehri on sone) but the floodplain is narrow, only 3 to 5 km wide. In the past, the Son has been notorious for changing course, as it is traceable from several old beds near its east bank. In modern times this tendency has been checked with the anicut at Dehri, and now more so with the Indrapuri Barrage.
After passing the steep escarpments of the Kaimur range, it flows straight across the plain to the Ganges. For much of this distance it is over two miles wide, and at one point, opposite Tilothu three miles wide. In the dry weather there is vast expanse of sand, with a stream not more than a hundred yards wide, and the hot west winds pile up the sand on the east bank, making natural embankments. After heavy rain in the hills even this wide bed cannot carry the waters of the Son and disastrous floods in Shahabad, Gaya, and Patna are not uncommon.
The first dam on the Son was built in 1873–74 at Dehri. Later the Indrapuri Barrage was constructed, 8 km upstream, and commissioned in 1968. The Bansagar Dam in Madhya Pradesh was commissioned in 2008.
(Source: wikipedia accessed on 10.01.2017)