Abstract: To improve the accuracy, numerical stability and computational efficiency of the existing 2D numerical models of flood propagation and inundation, this paper presents a full hydrodynamic model based on the GPU acceleration techniques (GAST). The model is applied to reproduce a flood event with a return period of 100 years that occurred in Morpeth town, UK. Two grid resolutions of 5 m and 2 m are used in the model and the MIKE21 FM model to investigate different inundation patterns. It is found that the GAST model can achieve an error range of only 0.96% - 4.36% in its calculations of the inundated area and its run-time is 2.17 h and 9.00 h for the 5m and 2m resolutions respectively. It improves computational accuracy and efficiency by 1.07 - 19.55 times and 3.40 - 11.78 times respectively relative to the MIKE21 FM. And this superiority becomes more prominent as the number of grids increases. Thus the GAST model is an ideal tool for modelling flood propagation and inundation.