What is River profile?

The longitudinal profile or long profile of a river is a section showing its slope from source to mouth;

Initially it is irregular, with rapids and waterfalls in the upper reaches, but later it becomes much smoother. The section then takes the form of a curve, much flattened towards the mouth, with the concavity upwards. A river is constantly engaged in the processes of Aggradation, and Degradation and if these two processes are balanced the river is said to be graded or to have achieved its profile of equilibrium, a condition that in practice is seldom attained.