RELATION BETWEEN MEAN AND MAXIMUM VELOCITIES IN A NATURAL RIVER

The cross-sectional mean velocity is an important variable in open-cha nnel hydraulics, whereas the maximum velocity in a channel cross secti on is mentioned very little. However, the maximum velocity in a channe l cross section might be as important as the cross-sectional mean velo city. This is because the measurable maximum velocity can be considere d as a ''signal,'' from which one can know the range of the velocity i n a channel cross section. This study explored the relation between th e cross-sectional mean and maximum velocities in a natural river by us ing velocity data collected from the Mississippi River. The relation o f the maximum velocity to the cross-sectional mean velocity on differe nt straight reaches in the Mississippi River is perfectly linear. The relation of the maximum velocity to the cross-sectional mean velocity on different river bends is still linear and changes with the r(c)/B v alue slightly. The conclusions are preliminary because of the limited amount of data.