Explicit GPU Based Second-Order Finite-Difference Modeling on a High Resolution Surface, Feather River, California

Abstract

An explicit second-order finite-difference computer model was developed and optimized for solution of the Shallow Water Equations. The model was applied to the Feather River below the Oroville Dam and Thermalito Afterbay near Gridley, California. Two versions of the computer model were constructed to run on either Central Processing Units or Graphical Processing Units, utilizing Fortran, C, C++, and the NVIDIA Compute Unified Device Architecture (CUDA) parallel computing platform. The underlying algorithm utilizes a structured grid and is capable of handling the wetting and drying of cells. It was developed with view to maximizing stability while maintaining accuracy, and allowing for flexibility of the computational domain. Comparisons with analytical and observed results showed the proposed methodology to be robust, accurate, and efficient. The models were applied to a section of the Feather River where observations of flow depths and volumetric flow rates are available for multiple flood events. The domain surface was partially developed using high-resolution photogrammetric data obtained through use of unmanned aerial vehicles. Runtimes and results were compared to the United States Bureau of Reclamations’ implicit finite-volume numerical method and with field observation with generally good correspondence.