To calculate average velocity from velocity profiles at different lateral positions in a channel, the mean of the discrete velocity points can be used if they are evenly spaced. For unevenly spaced points, a weighted average may be necessary. The average velocity can also be determined by the change in position over time if the starting and ending times are known. The discussion highlights the need for clarity regarding the attachment with point velocities at various depths and lateral positions. Understanding the cross-section's dimensions, including wall locations, is crucial for accurate calculations.