Modified Parker (1990) Bedload Equation

The modified Parker bedload equation incorporates the method of critical stress calculation of Shvidchenko (2000). The general form of the modified equation is the same as the original one:

where

and the normalized dimensionless bed shear stress is defied as

where

and is the reference stress corresponding to a small reference transport rate , which is related to the Shvidchenko’s (2000) critical stress as

The value of critical stress is defined as:

a is the particle mobility factor,

b is the mixture mobility factor,

is the mixture geometric standard deviation (for bed surface):

is the hiding function,

and e is the hiding parameter,

The suggested applicability of the modified Parker equation is for uniform/graded coarse sand and gravel.