  We introduce a GPU-accelerated simulation tool, named Modeling on Shallow
Flows with Efficient Simulation for Two-Phase Debris Flows (MoSES_2PDF), of
which the input and output data can be linked to the GIS system for engineering
application. MoSES_2PDF is developed based on the CUDA structure so that it can
well run with different NVIDIA GPU cards, once the CUDA vers. 9.2 (or higher)
is installed. The performance of the MoSES_2PDF is evaluated, and it is found
that the present GPU-CUDA implementation can enhance efficiency by up to 230
folds, depending on the PC/workstations, models of GPU card, and the mesh
numbers in the computation domain. Two numerical examples are illustrated with
two distinct initial inflow conditions, which are included in two modes of
MoSES_2PDF, respectively. In the numerical example of a large-scale event, the
2009 Hsiaolin event, the results computed by two distinct NVIDIA GPU cards
(RTX-2080-Ti and Tesla-V100) are found to be identical but only tiny deviation
is figured out in comparison with the results computed by the conventional
single-core CPU-code. It is speculated to be caused by the different structures
in the source codes and some float/double operations. In addition to the
illustration in the GIS system, the computed results by MoSES\_2PDF can also be
shown with animated 3D graphics in the ANSI-Platform, where the user can
interact with 3D scenes. The feasibility, features, and facilities of
MoSES\_2PDF are demonstrated with respect to the two numerical examples
concerning two real events.
