A new grid-associated algorithm in the distributed hydrological model simulations

This paper presents a new grid-associated algorithm to improve the performance of a D8 algorithm based distributed hydrological model computation. The algorithm is based on the well known single-flow D8 algorithm of grid flow. This algorithm allocates calculation priorities according to the distance between the units and the outlet, then carries out the ergodic computations of the hydrological units according to the priority division. For the parallelized algorithm, a standard thread-level shared memory system for parallel programming (OpenMP-Open specifications for Multi Processing) was introduced, and the parallel coding was implemented in C language. A case study showed that the absolute speed-up ratio of the grid-associated algorithm is 1.64 over the original D8 algorithm, and the linear speed-up ratio of the parallel associated algorithm is 2.42 under 4 cores. The parallel grid-associated algorithm can be applied to a variety of research fields that use the grid method.