Stereoscopic analysis of landsides on the southern slopes of the Mt. Medvednica and landslide features assessment – examples and field check

The term landslide comprises almost all varieties of mass movements on slopes. Landslide inventory contains data about landslides on certain area. Landslide inventory map shows the locations of the landslides and can contain other additional data. Landslide maps can be prepared using different techniques. Landslide inventory maps are usually used in determination of landslide mitigation measures, civil engineering and urban planning. Spatial distribution of landslides and their activity is subject of change during time and that is a reason for development of landslide inventory maps from different periods (can be done by stereoscopic analysis of photographs from different periods). Data in landslide inventory is one of the most basic and most needed in further analysis in landslide susceptibility, landslide hazard and landslide risk. Most widespread and most used method in landslide inventory development is geomorphological mapping of terrain and usage of different methods of remote sensing (for example stereoscopic analysis). Even today, use and stereoscopic analysis of aerial photography has defined a prevailing standard and a benchmark against which new technologies to detect and map landslides are compared. Analytic hierarchy process (AHP) is a structural technique for data organization and analysis used for obtaining complex decisions. AHP can be used practically in landslide mapping and assessment of characteristic landslide features. Stereoscopic analysis was used in combination with AHP methodology for the assessment of characteristic landslide features on the southern slopes of the Mt. Medvednica. Assessment of characteristic landslide features for the identified landslides was based on the visible landslide features on photography (stereoscopic analysis), which included assessment of: landslide features (features at landslide body, features of landslide body boundary and features at main scarp) and features at landslide body toe part, slope morphology and land cover. Identified landslides were classified based on visible landslide features and according AHP score. Investigation encompassed: (i) criteria development for application of AHP methodology in area of research (100 km2), (ii) interpretation of 130 aerial photos of two generations, (iii) landslide inventory development and preparation of landslide inventory map and (iv) methodology verification on the basis of comparison with existing data and field check. In the paper some characteristic examples of identified landsides on the southern slopes of the Mt. Medvednica determined by stereoscopic analysis are given, with AHP score and field report. The methodology presented in this paper (stereoscopic analysis in combination with AHP methodology), is used for the first time in Croatia in landslide inventory development and preparation of landslide inventory map. Also the methodology and the established criteria is applicable in landslide inventory development and preparation of landslide inventory map in other areas where landslides exists in same or similar conditions, in Croatia or worldwide. Since there is no uniform landslide inventory for the whole territory of Croatia, the used methodology and the developed criteria also can be used as guidelines for the usage of remote sensing in landslide inventory development on national level.