ARTYKUŁY NAUKOWE Cyfrowa analiza fotogrametryczna tempa i charakteru ruchów masowych skarpy rzecznej doliny Bugu w rejonie Drohiczyna (południowe Podlasie)

Abstract

Digital photogrammetric analysis of the rate and nature of mass movements of the Bug river valley escarpment in the Drohiczyna area (southern Podlasie).A b s t r a c t. The traditional approach in photogrammetric studies relies mainly on the analysis of topographic maps, supported by geological and geomorphological field mapping. This paper presents an application of the modern method of three-dimensional earth imaging – Airborne Laser Scanning. The major advantage of this method is the filtering procedure, which allows to removing vegetation and other objects from the analysed surface, resulting in more precise terrain model. We used aerial photographs for preparation of two photogrammetric digital terrain models (DTMs), which were subsequently compared to evaluate dynamic properties of landslide areas. The difference between gratings within digital models was used to determine horizontal shifts in the area of landslide. The discrepancy presented observed in the shaded relief image characterises positive elevations (erosion) shown in reddish colour, and negative ones (accumulation) displayed in bluish. The maximum scarp retreat driven by landsliding processes reached 17 m during the last 53 years,with ca. 562 m3 of accumulated colluvium.