Resumen
Depression (pit or sink) filling is a key preprocessing step for the automatic hydrologic analysis of surface topography. The Planchon and Darboux (P&D) algorithm is a widely used depression filling algorithm. In this study, we propose an improved variant over the fastest sequential variant of the P&D algorithm for depression filling. Our variant introduces two important improvements compared with the fastest variant of the P&D algorithm, and greatly reduces redundant computation, as well as requires less memory space. Our algorithm can be easily integrated into many of the existing hydrologic analysis software packages. Moreover, our algorithm shares the same versatility as the P&D algorithm. Depressions can be replaced with surfaces either strictly horizontal, or slightly sloping. In the latter case, it is easier to calculate the flow direction matrix.