Algorithm for karst depression recognition using digital terrain Models

An algorithm of automated karst depression recognition uses a digital terrain model (DTM) and mainly applies the methods of a moving window with a kernel size of 3 × 3 cells using focal functions. It is divided into four parts: watershed calculation, depression delineation, higher level depression delineation and elimination of non-karst depressions. The essential part of the algorithm is the delineation of depression by the elevation of the lowest border cell of watershed. Depressions at higher levels are recognised by filling previously recognised depressions. The performance of algorithm was tested on test area in the Kras region (Slovenia) using DTMs with a spatial resolution of 12.5 m and 3 m. The results mainly depend on the DTM characteristics and quality, especially of their spatial resolution.