Son River
• Son River, also spelled Sone, originates in Madhya Pradesh, and is a major tributary of the Ganges (Ganga) River.
• After passing through Manpur, it flows north before turning northeast. After a 487-mile (784-km) journey through the Kaimur Range, the river joins the Ganges above Patna.
• The Son Valley is almost a geological continuation of the Narmada River valley to the southwest. It is mostly forested and has a sparse population.
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• The Kaimur Range to the north and the Chota Nagpur plateau to the south form the valley's boundaries.
• The Son is unimportant for navigation, and the river's flow is seasonal. On some of its tributaries, dams have been built.
• Son River is the largest of Ganga's southern tributaries, beginning near Amarkantak in Madhya Pradesh near the Narmada River's source and flowing north-northwest through Madhya Pradesh before turning sharply eastward where it meets the Kaimur Range, which runs southwest-northeast.
• The Son flows east-northeast through Uttar Pradesh, Jharkhand, and Bihar before joining the Ganga just above Patna, paralleling the Kaimur hills.
• Rihand and the North Koel are the two main tributaries of the Son River.
• The Son has a steep gradient (35–55 cm per km) and ephemeral regimes, becoming a raging river with rainwater in the catchment area but quickly turning into a fordable stream.
• The Rihand River flows through the Indian states of Chhattisgarh and Uttar Pradesh and is a tributary of the Son River. It rises in the Matiranga hills of Chhattisgarh. Rihand meets Son in Uttar Pradesh's Sonbhadra.