Numerical model for short-term fate of dumped material from barge is developed by using MAC method.
　The model is formulated to vertically two-dimensionan is performed to the relation with time increment, grid interval, the wieigh and the number of marker, settling velocity, rebound on the bottom, the effect of environmental flow, etc.
　The following properties are conclusively confirmed; material dispersion and induced flow are qualititatively reproduced, the falling velocity as the group of the material is greater than that of each particle, grid interval has strong influence to resulting solution, and the total weight of marker decides the flow and dispersion.
　Several suggestions which shoudl be solved in advance are described for the application of the model to practical problems.