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The paper discusses landslides investigated in a Brda river valley in the region of the town Koronowo near Bydgoszcz (Kujawsko-Pomorskie Voivodeship) in the Polish Lowlands. Due to morphologic and geologic setting the area is prone to slope instability. Out of 32 identified landslides, 9 were selected for detailed examination. To register a nature and rate of failures a complex monitoring system was installed on slopes where the selected landslides resulted in damages to municipal infrastructure. The system was facilitated with inclinometers and piezometers, supported by a network of GPS-RTK geodetic benchmarks as well as with a recording station. The performed examination revealed that the most unfavourable arrangement of the layers is, when under a non-cohesive soil lies a cohesive impermeable layer. The landslides are rather shallow ones (except for two incidents) with slow rate of displacement. The landslide-triggering factor is water originating from precipitation and snow melting. Influence of water was especially significant in early spring 2011, due to the combined effect of snow melting and infiltration of thawing water originating from the former, as well as exceptionally high rainfalls. The influence of hydrologic conditions on slope deformations is complex. There is a significant time lag between a movement initiation and unfavourable hydrometeorological conditions. That is exemplified with the landslide that was initiated in February-March 2011 in consequence of atmospheric conditions of November-December 2010. The results formed the background for inventing engineering treatment measures aiming at current remedial stabilisation of slopes and mitigation of possible landsliding in the future.

The Ca’ Lita landslide is a large and deep-seated mass movement located in the northern Apennines, about 70 kmwest of Bologna (northern Italy). It consists of a composite landslide that affects Cretaceous to Eocene flyschrock masses and chaotic complexes. Many of the sectors making up the landslide have resumed activity between2002 and 2006, threatening some villages and an important road connecting several key industrial facilitieslocated in the upper watershed. This paper presents the management of the emergency, dealing with theinvestigation campaigns (geological, geomorphological and LiDAR surveys, borehole drillings, seismic surveys),with the monitoring (in situ instrumentation) and with the design and construction of mitigation measures. Thewhole process, from landslide reactivation to date, has been modelled on a numerical basis with the finitedifference code FLAC 2D, to assess the efficiency of the mitigation system and to propose furthercountermeasure works in different scenarios

The paper presents a 3D (spatial) analysis of deformation processes in the landslide slope Bystrzyca in Szymbark near Gorlice (Low Beskid – Carpathians; N 49°37′ 09″, E 21°05′ 49″) carried out by the computer code FLAC3D based on the finite difference method. The numerical analysis was performed to determine the influence of the orientation of layers and discontinuities and of hydrogeological conditions on slope deformations and the failure mechanism during sliding processes. The massif is modeled as an elasto-plastic medium obeying the Coulomb-Mohr criterion. Two variants of hydrogeological conditions are analyzed, namely the “dry slope” (without water) and the “wet slope” (entirely saturated). The influence of the orientation of discontinuities (modeled as “ubiquitous”) on the landslide mechanism is investigated as well. Few orientations of discontinuities with respect to the dip direction of the slope surface are considered, namely consequent, insequent, and subsequent (two variants in each case). The results show a clear impact of the pattern of discontinuities and hydrogeological conditions on the deformational behavior of the landslide and the shape of the slip surface. The 3D approach and results of the numerical simulation of the landslide movement prove the necessity of 3D modeling in some cases.