MULTIPLE FLOW DIRECTION ALGORITHMS FOR RUNOFF MODELING IN GRID BASED ELEVATION MODELS - AN EMPIRICAL-EVALUATION

When pathways for groundwater flow are defined in grid based elevation models, the grid structure creates some obstacles as it only allows for eight flow directions. Earlier algorithms have used arbitrarily designed flow distributions, which have resulted in either too diverging or too converging flow patterns. This study defines a computationally simple distribution function, where the converging nature (x) can be altered. A material of reference flow distributions was produced through simulation in four elevation models. The distribution function was tested for different values on x, against the reference. The results show a stable correlation pattern between the tested function and the reference. Optimum values on x were found, which suggest that the flow distribution from a grid cell should be weighted with the slope gradient raised to the power of 4-6.