Shields formula

The Shields formula is a formula for the stability calculation of granular material (sand, gravel) in running water.

The stability of granular material in flow can be determined by the Shields formula or the Izbash formula. The first is more suitable for fine grain material (such as sand and gravel), while the Izbash formula is more suitable for larger stone. The Shields formula was developed by Albert F. Shields (1908-1974). In fact, the Shields method determines whether or not the soil material will move. The Shields parameter thus determines whether or not there is a beginning of movement.^{[1] [2]}