12.2.12. Straight Rivers In the straight reaches of a river, its section has the shape of a trough and maximum velocity of flow occurs in the middle of the section. It is very difficult to find the straight reach of an alluvial river over large lengths. Alluvial rivers seldom run straight through a distance greater than ten times the river width (1). Even in the apparent straight reaches, the line of maximum depth - commonly known as talweg – moves back and forth from one khadir (permanent bank) to another khadir.
