The starting point of a river is called a source. A smaller river that flows into a larger river is a tributary.
The starting point of godavari river is trimbakeshwar , near nasik , maharashtra
river mouth
glaciers
The starting point of the Sindh River is the Mansar Lake in the Udhampur district of Jammu and Kashmir, India.
kishtawar
bangladesh
The Missouri River and the Mississippi River are at the starting point of the Lewis and Clark expedition.
mostly from glaciers and mountains
mostly from glaciers and mountains
head watersIt is called the source.
The mouth of the river is NOT called the start. The mouth is the end of a river. The headwaters refers to the starting point(s). The starting point is called the source.