A fast and simple algorithm for calculating flow accumulation matrices from raster digital elevation

Calculating the flow accumulation matrix is an essential step for many hydrological and topographical analyses. This study gives an overview of the existing algorithms for flow accumulation calculations for single-flow direction matrices. A fast and simple algorithm for calculating flow accumulation matrices is proposed in this study. The algorithm identifies three types of cells in a flow direction matrix: source cells, intersection cells, and interior cells. It traverses all source cells and traces the downstream interior cells of each source cell until an intersection cell is encountered. An intersection cell is treated as an interior cell when its last drainage path is traced and the tracing continues with its downstream cells. Experiments are conducted on thirty datasets with a resolution of 3 m. Compared with the existing algorithms for flow accumulation calculation, the proposed algorithm is easy to implement, runs much faster than existing algorithms, and generally requires less memory space.