Multi-type sweeping for improving the efficiency of flow accumulation calculation

Flow accumulation is an important terrain attribute that has many applications. The computation of flow accumulation, however, is time consuming, which especially becomes an issue as high-resolution DEMs are getting increasingly available. In this study, we conducted experiments of sweeping the DEM starting from different corners and in different ways - by rows or by columns - when doing the cell-wise calculation. It turned out that a combination of different sweeps can be considerably more efficient than the conventional algorithm that employs single-type sweeping.