Assessment of freely available DSMs for automatic karst feature detection

The purpose of this work is to present the detection and qualification of natural karst depressions in southern Ksiromero, SW Aitoloakarnania Prefecture, Western Greece, by the use of freely available digital surface model (DSM) data in line with the geographical information systems—GIS. The study area is a part of the Ionian geotectonic zone whose geological background consists of the Triassic evaporates and Triassic carbonate breccias. The after-Triassic carbonate series, which consist of the Jurassic limestones, the Cretaceous limestones and the Eocene limestones, are also presented in the study area. Several DSMs such as ASTER GDEM, SRTM DEM, ALOS Global DSM, and a DSM generated from Sentinel-1 data were evaluated so as to be used for the automatic karst detection. Furthermore, a karst detection procedure applied on DSMs was performed with the aid of analogue and digital air photos. Additionally, the aforementioned procedure was applied also on DEM with the aid of digitized contours referring to topographic maps characterized by a scale of 1/50,000. All the detected features have been also validated via in situ observations. Finally, all DSMs presented herein are characterized by similar percentage of success in terms of automatic karst detection, regardless their spatial resolution and height accuracy. Their rate varies from 66 to 73%.