Performance Study of Parallel Algorithms in pWASH123D

Since January 2003, the U.S. Army Engineer Research and Development Center has been developing a parallel watershed code, pWASH123D, and its graphical user interface in the Department of Defense Groundwater Modeling System in collaboration with Brigham Young University. To date, pWASH123D has a complete suite of water flow simulations in a watershed system that can be conceptualized as a combination of one-dimensional (1-D) channel network, 2-D overland regimes, and 3-D subsurface media. This paper presents the outcome of a performance study on the parallel algorithms currently employed in pWASH123D. The experimental area includes a 570-square-mile domain covering most of the land south of the Tamiami Train in South Florida and north of the Gulf of Mexico, Florida Bay, and Biscayne Bay. This area is discretized to three mesh resolutions—coarse, medium, and fine meshes—to identify the performance bottleneck. Problems are designed to investigate the parallel strategy for the 1-D component. Major findings from the study are presented in this paper.