Dear Vinay,

Please check this useful PDF attachment.

Good luck

I know of no specific size classification of bars to suggest, as the size would depend to some degree on stream type and size, gradient, sinuosity, sediment supply, geology, valley form, etc.  There are various types of bar features that relate to their channel position (point, side, traverse, in-channel bars), and function.  There are also differing features in tidal and delta systems.  In a gully or other actively degrading system, the bars are often limited, while in braided streams and aggrading systems can effect most of the channel and sometimes the valley surface.  Clean water systems such as below dams, may have truncated or abandoned bars from erosion and degradation.  The types of bar substrates are sometimes described from a particle size analysis, but if you are just interested in sand bars, this may not be as helpful.  .