Numerical computations on sediment transport models base on threshold sediment motions of shield’s graphic due to simulation of the groyne placement analysis

The numerical model of sediment transport modelling is the computer program was constructed composed of 2-D flow by Navier-Stoke equation, sediment transport equations and bad deformations equations. In solving of sediment transport and bad deformations equation, required threshold of sediment that is the critical stress of motion parameters of each subgrade gradations, but the critical stress motion parameters was calculated from searched on the Shield's diagram, that’s always consideration of each process computations, while in the computer program, implementation of sediment transport done repeatedly so that the usage of Shield’s diagram in the computer program will be difficulty because to applied of Shield’s diagram can be do manually. Therefore, to usage of graphs on the computer program mush be abandoned and needs an effort to modify the Shield's diagram into mathematical equations. This paper describes of manually process of the Shield's diagram become a mathematical equation that can be applied easily in computer programming.