The research studies the effect of change of the Tigris River's surface stage on groundwater movement by building a three-dimension model using GMS model for a catchment area in Baghdad city. The model is built and calibrated by using the information of 16 wells for the year 2015 . Three scenarios of river elevation stage are used when the stage elevation is maximum, average and minimum. The movement of groundwater according to the results was from the north-west to the Tigris River location. Also, the results show the velocity of groundwater in case of the minimum water surface level stage is greater than the other cases because of the high hydraulic gradient. The velocity of groundwater in layer one for all cases is very slow because of the low permeability.