crossing the Son River. Sone River is called 'सोन / सोने' in Hindi, but called 'शोण' in Sanskrit, a rare instance of an Indian river having masculine name. Damodara and Brahmaputra also have masculine name. This river is mentioned as SoNai in
Sangam Tamil literature Kuṟuntokai as early as 2nd century CE. The Sone originates near
Pendra in
Chhattisgarh, just east of the headwater of the
Narmada River, and flows north-northwest through
Shahdol district in
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.
Arwal,
Daudnagar,
Deori,
Rohtasgarh,
Dehri,
Sonbhadra and
Maner are some of the major cities situated on Sone River. The Sone river which is long, is one of the longest Indian rivers. Its chief tributaries are the
Rihand,
Kanhar and the
North Koel. The Son has a steep
gradient (35–55 cm per km) with quick
run-off and
ephemeral regimes, becoming a roaring river with the rain-waters in the
catchment area but turning quickly into a fordable stream. The Son, being wide and shallow, leaves disconnected pools of water in the remaining parts of the year. The channel of the Son is very wide (about 5 km at
Dehri) but the
floodplain is narrow, only wide. The meeting point with
North Koel the width of Sone River is . In the past, the Son has been notorious for changing course. As it is traceable from several old beds near its east bank, the river changed its course more than 5 times. In modern times this tendency has been checked with the
anicut at Dehri, and now more so with the
Indrapuri Barrage. In Bihar, this river forms the border line between the
Bhojpuri- and
Magahi-speaking regions.
Sir John Houlton, the British administrator, described the Son as follows, "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 a 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." ==Dams==