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The effect of climate change on rockfalls in the German low mountain regions is investigated following two different approaches. The first approach uses a logistic regression model that describes the combined effect of precipitation, freeze–thaw cycles, and fissure water on rockfall probability. The climate change signal for the past 6 decades is analysed by applying the model to meteorological observations. The possible effect of climate change until the end of the century is explored by applying the statistical model to the output of a multi-model ensemble of 23 regional climate scenario simulations. It is found that the number of days per year exhibiting an above-average probability for rockfalls has mostly been decreasing during the last few decades. Statistical significance is, however, present at only a few sites. A robust and statistically significant decrease can be seen in the Representative Concentration Pathway (RCP) climate scenario 8.5 (RCP8.5) simulations for Germany and neighbouring regions, locally falling below -10 % when comparing the last 30 years of the 20th century to the last 30 years of the 21st century. The most important factor determining the projected decrease in rockfall probability is a reduction in the number of freeze–thaw cycles expected under future climate conditions. For the second approach four large-scale meteorological patterns that are associated with enhanced rockfall probability are identified from reanalysis data. The frequency of all four patterns exhibits a seasonal cycle that maximises in the cold half of the year (winter and spring). Trends in the number of days that can be assigned to these patterns are determined both in meteorological reanalysis data and in climate simulations. In the reanalysis no statistically significant trend is found. For the future scenario simulations all climate models show a statistically significant decrease in the number of rockfall-promoting weather situations. [ABSTRACT FROM AUTHOR]

The effect of climate change on rockfall in the German low mountain regions is investigated following two different approaches. The first approach uses a logistic regression model that describes the combined effect of precipitation, freeze-thaw cycles and fissure water on rockfall probability. The climate change signal for past decades is analysed by applying the model to meteorological observations. The possible effect of climate change until the end of the century is explored by applying the statistical model to the output of a multi-model ensemble of 23 regional climate scenario simulations. It is found that the number of days per year exhibiting an above-average probability for rockfall has been mostly decreasing during the last decades. Statistical significance is, however, present only at few sites. A robust and statistically significant decrease can be seen in the RCP8.5 climate scenario simulations for Germany and neighbouring regions, locally falling below -10 % when comparing the last 30 years of the 20th century to the last 30 years of the 21st century. The most important factor determining the projected decrease in rockfall probability is a reduction in the number of freeze-thaw cycles expected under future climate conditions. For the second approach four large-scale meteorological patterns that are associated with enhanced rockfall probability are identified from reanalysis data. The frequency of all four patterns exhibits a seasonal cycle that maximizes in the cold half of the year (winter/spring). Trends in the number of days that can be assigned to these patterns are determined both in meteorological reanalysis data and in climate simulations. In the reanalysis no statistically significant trend is found. For the future scenario simulations all climate models show a statistically significant decrease in the number of rockfall promoting weather situations. [ABSTRACT FROM AUTHOR]

Rapidly evolving floods are rare but powerful drivers of landscape reorganisation that have severe and long-lasting impacts on both the functions of a landscape's subsystems and the affected society. The July 2021 flood that particularly hit several river catchments of the Eifel region in western Germany and Belgium was a drastic example. While media and scientists highlighted the meteorological and hydrological aspects of this flood, it was not just the rising water levels in the main valleys that posed a hazard, caused damage, and drove environmental reorganisation. Instead, the concurrent coupling of landscape elements and the wood, sediment, and debris carried by the fast-flowing water made this flood so devastating and difficult to predict. Because more intense floods are able to interact with more landscape components, they at times reveal rare non-linear feedbacks, which may be hidden during smaller events due to their high thresholds of initiation. Here, we briefly review the boundary conditions of the 14–15 July 2021 flood and discuss the emerging features that made this event different from previous floods. We identify hillslope processes, aspects of debris mobilisation, the legacy of sustained human land use, and emerging process connections and feedbacks as critical non-hydrological dimensions of the flood. With this landscape scale perspective, we develop requirements for improved future event anticipation, mitigation, and fundamental system understanding. [ABSTRACT FROM AUTHOR]

A rockfall dataset for Germany is analysed with the objective of identifying the meteorological and hydrological (pre-)conditions that change the probability for such events in central Europe. The factors investigated in the analysis are precipitation amount and intensity, freeze–thaw cycles, and subsurface moisture. As there is no suitable observational dataset for all relevant subsurface moisture types (e.g. water in rock pores and cleft water) available, simulated soil moisture and a proxy for pore water are tested as substitutes. The potential triggering factors were analysed both for the day of the event and for the days leading up to it. A logistic regression model was built, which considers individual potential triggering factors and their interactions. It is found that the most important factor influencing rockfall probability in the research area is the precipitation amount at the day of the event, but the water content of the ground on that day and freeze–thaw cycles in the days prior to the event also influence the hazard probability. Comparing simulated soil moisture and the pore-water proxy as predictors for rockfall reveals that the proxy, calculated as accumulated precipitation minus potential evaporation, performs slightly better in the statistical model. Using the statistical model, the effects of meteorological conditions on rockfall probability in German low mountain ranges can be quantified. The model suggests that precipitation is most efficient when the pore-water content of the ground is high. An increase in daily precipitation from its local 50th percentile to its 90th percentile approximately doubles the probability for a rockfall event under median pore-water conditions. When the pore-water proxy is at its 95th percentile, the same increase in precipitation leads to a 4-fold increase in rockfall probability. The occurrence of a freeze–thaw cycle in the preceding days increases the rockfall hazard by about 50 %. The most critical combination can therefore be expected in winter and at the beginning of spring after a freeze–thaw transition, which is followed by a day with high precipitation amounts and takes place in a region preconditioned by a high level of subsurface moisture. [ABSTRACT FROM AUTHOR]

Mass movements are linked to increasing amounts of damage and disruptions to transportation infrastructures. A valid risk assessment in order to reduce future costs is not always appropriate, as adequate information on landslide data is missing. The presented study estimates the rockfall susceptibility on a rural road network in the Harz mountains using a bivariate statistical method (information value method). The model is validated using a receiver operating characteristic (ROC) analysis. In addition, the vulnerability of the road network is estimated using vulnerability indicators. The susceptibility model assigns a high or very high susceptibility to 23% of the area in the road network corridor. The relevant road sections are linked to high slope values, NE orientations of road sections, and low-to-moderate vulnerability values. The highest vulnerability values can be found on marginal road sections with high average daily traffic volumes. The combination of the presented methods proposes an easily applicable estimate of vulnerability where conventional methods (i.e., vulnerability curves, matrices) cannot be implemented. [ABSTRACT FROM AUTHOR]

A rockfall dataset for Germany is analysed with the objective of identifying the meteorological and hydrological (pre-) conditions that change the probability for such events in Central Europe. The factors investigated in the analysis are precipitation amount and intensity, freeze-thawing cycles as well as sub-surface moisture. As there is no suitable observational dataset for all relevant sub-surface moisture types (e.g. water in rock pores and cleft water) available, simulated soil moisture and parameterised pore water are tested as substitutes. The potential triggering factors were analysed both for the day of the event as well as for the days leading up to the event. It is found that the most important factor influencing rockfall probability in the research area is precipitation amount at the day of the event but the water content of the ground on that day and freeze-thawing cycles in the days prior to the event also influence the hazard probability. Comparing results with simulated soil moisture and parameterised pore water revealed that precipitation minus potential evaporation evaluated for a weekly period performs well as a proxy for the relevant sub-surface moisture types. A logistic regression model was built, which considers individual potential triggering factors as well as their interactions. Using this model the effects of meteorological conditions on rockfall probability in the Central European low mountain ranges can be quantified. The model suggests that precipitation is most efficient, when the moisture content of the ground is high. An increase of daily precipitation from its local 50th percentile to its 90th percentile approximately doubles the probability for a rockfall event under median sub-surface moisture conditions. When the moisture content of the ground is at its 95th percentile the same increase in precipitation leads to a four-fold increase in rockfall probability. The occurrence of a freeze-thaw cycle in the preceding days can further increase the rockfall hazard. The most critical combination can be expected in the winter season after a freeze-thaw transition which is followed by a day with high precipitation amounts and takes place in a region preconditioned by a high level of sub-surface moisture. [ABSTRACT FROM AUTHOR]

With growing urbanization, an increasing number of landslides worldwide are linked to construction works, especially along transportation routes. To get a better understanding of these post‐construction landslides at artificial waterways, archive studies have been conducted, in addition to analysis of historical scientific literature and technical reports. The resultant database is used to describe the occurrence and the characteristics of the landslides at the Mittelland Canal, and to evaluate aspects of conditioning and preparatory factors, potential triggers and applied mitigation measures. The Mittelland Canal has been chosen because it is one of the most important artificial waterways in Europe, and the high number of landslides that occur there is unique. In particular, landslides at the Mittelland Canal were frequently reported in the first half of the 20th century. The susceptibility to landslides is strongly influenced by material characteristics, as a large number of landslides is linked to sites where fine‐grained mudstone is abundant, which quickly decomposes under immersion in water or under dynamic stress. In addition, landslides can be linked to the creation of over‐steepened slopes. Construction works can also be considered another preparatory factor for landslides. In addition, some landslides in World War II appear to be connected to the blast of aerial bombings. Precipitation seems to play a minor role in triggering landslides. The applied mitigation measures were developed recently, marking the importance of the canal as a transportation route. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study presents an evaluation of a comprehensive dataset with information on about 700 recorded rockfall events in Germany for the first time. The focus is on the analysis of monthly distributions of three rockfall clusters in German low mountain ranges and of three elevation classes to provide an overview of the characteristic seasonal occurrence of rockfalls in Germany. Each rockfall distribution is correlated with records of meteorological station clusters which are representative for the long‐term climate conditions of the particular rockfall cluster and elevation class, respectively. The stored parameters in the dataset (year of occurrence, rock volumes, slope angles, affected objects) are evaluated to complete the extensive and differentiated overview of rockfalls in Germany. The analyses of the distributions of the three rockfall clusters show a distinct event concentration in the winter months. Differences are apparent between the monthly distributions of the elevation classes in which clear peaks are partially visible. Freeze–thaw cycles are considered to be the major trigger of winter rockfalls in Germany. Overall, the presented results may serve as a basis for further studies in the German low mountain ranges. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The Rhenodanubian Flysch zone of the eastern Alps of Austria is considered to be susceptible to landslides. In the study area, an undulating low mountain landscape of the eastern European Prealps, the Flysch bedrock is superimposed by Quaternary periglacial cover beds and loess. Both, the petrography of the bedrock and the soil mechanical properties of Quaternary sediments control the slope dynamics. A database compiled for the study area comprises about 200 datasets on landslide and rock fall hazards. It covers a time span between 1771 and 2007 and shows clusters between 1940 and 1943, 1965 and 1966, 1979 and 1982 as well as in 2006. The study analyses slope stability in the light of slope formation phases with respect to weathering, erosion and geology. Furthermore, geomorphological and soil–geographical methods are combined with soil–mechanical calculations. The application of the concept of periglacial cover beds facilitates the distinction between Holocene and Pleistocene landforms and slide masses in the research area. As a result, the study shows that the properties of Quaternary sediments and the occurrence of the densely bedded basal cover beds are responsible for landslide susceptibility. The variable permeability in loess layers, in contrast to that in the underlying basal cover beds, consisting mainly of marls and clayey material, is one of the fundamental controlling factors of mass movements. In a temporal context it is evident that the stability of slopes in the study area is influenced by several phases of slope formation. The synopsis of field survey, morphometrical, geotechnical as well as laboratory analyses, and slope-stability calculation, gives evidence of five morphodynamic phases that partly reoccur in an alternating pattern. After having passed all phases, the stability of the slopes studied is increased, because modified soil–mechanical properties of the slide masses become important. As a consequence, the critical slope angle is raised by 3-5°. [Copyright &y& Elsevier]

Abstract: The sediments of Holocene floodplain banks in several river catchments in the southern Cape region, South Africa, were sedimentologically investigated and radiometrically dated. The study resulted in a differentiation into two sedimentation phases. The sedimentation of the older phase starts directly above the bedrock or above coarse gravels. These sediments are composed of 2.5–3 m of interbedded sand, silt, and clay. In part, they are stratified by organic horizons and inclusions. The radiocarbon dating of numerous organic horizons as well as fossil wood shows that the sedimentation during the older phase occurred between 1215 and 875 years BP at the base, and 670 and 15 years BP at the top of this sequence. The sediments of the younger phase mainly consist of homogeneous fine sand and are at least 3 m thick, stratigraphically above the sediments of the older deposition phase. However, the sediments of the younger layer can also comprise the entire Holocene deposits situated above the current riverbed. These sediments are mainly of modern age and are partly deposits of centennial flood events. The context between the onset of sedimentation and the start of pastoral farming by settlers after AD 400, which has been archaeologically verified, supports the hypothesis that the first sedimentation phase was set off or favoured by the degradation of the natural vegetation cover as a result of livestock farming. Later, increased sedimentation as well as an increase in peak flows resulting from increased landscape degradation due to intensified pasture farming by the European settlers has to be assumed. [ABSTRACT FROM AUTHOR]

The Rhenodanubian Flysch of the northern Vienna Forest is composed of various layers of sandstones, marly shales, calcareous marls, and clay shists, which are covered by Quaternary periglacial cover beds and loess deposits. This area at the margin of the eastern Alps represents an undulating landscape of the Austrian low-mountain regions. The Vienna Forest Flysch region is considered to be susceptible to landslides. Both petrography of the bedrock and soil mechanical properties of the Quaternary sediments control the current slope dynamics in the study area. In a temporal context it is evident that the stability of slopes exceeding 27◦ is controlled by a succession of several steps of slope formation. On the basis of field surveys, laboratory analyses, and slope stability modelling, results from investigations on recent landslides demonstrate five different phases of slope formation. In general, after passing these phases the stability of studied slopes is increased, due to the different soil mechanical properties of the potential sliding masses. [ABSTRACT FROM AUTHOR]

In recent years, German laws pertaining to construction have been simplified with the goals of reducing administrative procedures and government expenditures. On the one hand, the new regulations are intended to simplify construction activities by the elimination of obstacles toward approval and by the simplification of governmental supervision procedures. On the other hand, a simplified approval process shifts the responsibility for compliance with building codes to the owners, consultants (architects, civil engineers, experts, etc.) and construction project managers. First experiences of damage to buildings show that streamlined construction approvals run the risk of neglecting basic geomorphologic and geologic fundamentals. Omissions are evident, which have led to failures at embankments and on building sites, causing considerable losses. The responsible administrations have reacted in different ways to the changed conditions, as far as they already are aware of the possible implications. In southern Lower Saxony State, the planning agencies have reacted to the growing responsibilities by attempting to determine at an early stage hazards in areas that are being developed. The practice aims to ensure that neither the planned construction activities nor the buildings themselves pose a threat for the residents. However, in the context of weighing these land-use decisions, it becomes apparent that in the future, administrative employees will have to be trained to foresee potential problems caused by the new regulations, while those affected by the decisions must receive advice on how to proceed. At the same time, latitudes and guidelines for dealing with geomorphologic hazards have to be defined. [ABSTRACT FROM AUTHOR]

Stratified periglacial sediments extensively cover the slopes of central European low mountain areas. Periglacial cover beds and loess-like sediments as most abundant strata influence many near-surface processes, forming an important component of the Earth's critical zone. The present study focusses on the analysis of a complex sequence of periglacial slope deposits with multiple intermediate layers and intercalated slope wash sediments in order to determine and date periods of intermediate layer formation. Since luminescence dating often provides inconsistent data for cover beds, there is need to reconsider the numerical dating strategy. This study hence places stronger emphasis on numerical dating of interbedded, sufficiently bleached slope wash sediments. The gained OSL-ages are more reliable and consistent and thus, provide a temporal framework for relative dating of intermediate layer formation cycles. In combination with paleosol relics the numerical ages allowed a chronostratigraphic interpretation of Late Pleistocene paleoenvironmental dynamics and slope evolution. Our findings not only prove multiple phases of intermediate layer formation in the study area during the last glacial period but also enabled the correlation of single intermediate layers with specific time spans, including Early and Middle Weichselian as well as the Late Glacial. Remnants of the Eemian soil in the studied sequence even indicate a Saalian age for the lowermost intermediate layer. The present study shows that luminescence dating of intercalated slope wash deposits instead of cover beds is a promising numerical dating strategy for the chronostratigraphic interpretation of cover bed sequences. The findings further illustrate that complex, fanned out periglacial sediment sequences form despite their scarcity important paleoenvironmental archives for Late Pleistocene periglacial landscape dynamics in central European low mountain areas. [ABSTRACT FROM AUTHOR]

Abstract: The correlation of sedimentary and pedogenetic processes in Lower Austria is difficult due to significant discontinuities and local variability in soil formation. This hampers landscape reconstruction at a regional scale. However, at a local scale distinct landscape formation processes represented by a shift from fluvial to aeolian deposition can be observed in the brickyard of Langenlois, Lower Austria. Sedimentological and mineralogical analyses in combination with palaeontological finds suggest that the fluvial deposition took place during the Middle Pleistocene. This attribution is confirmed by infra-red stimulated luminescence (IRSL) dating, which gives a minimum age of 300ka for the palaeosurface on which the fluvial sediments were deposited. This is consistent with a small faunal assemblage including Stephanorhinus sp., Dama sp. and an alcine cervid. Such a fauna is previously unknown in Austria; it indicates a Middle Pleistocene interglacial period. The low degree of weathering as well as Cryosols found in the loess sequence point to loess accumulation during the Last Glacial; the dating results (35–55ka) indicate prolonged loess deposition. No signs of pedogenesis could be found; this is surprising because in other areas this period is known for weak soil development. The lack of soil formation seems to be specific to the western part of Lower Austria, as is the complete erosion of the last glacial maximum (LGM) loess, which can not be found at Langenlois. [Copyright &y& Elsevier]

• Multi-methodological approach to a unique archive for the Holocene. • Micromorphological descriptions of complex polygenic soils and sediments. • The pedosediments are characterized and compared to international taxonomies. • Changes in soil properties are driven by parent material, relief, and land use. • These are isolated and their influence is discussed in detail. Sinkholes in the karstified Middle Keuper gypsum of Middle Franconia, Germany reveal numerous archeological findings and contain unique pedosedimentary records of landscape development and human-environment interaction during the Holocene. Mudstone-derived high clay contents result in a unique set of sedimentary and pedogenic properties of these archives in that all units exhibit vertic properties. Since the horizons have a polygenic history, detailed field and micromorphological observations, together with laboratory analyses (grain-size, color, iron-pedochemistry) are the basis for a classification of the pedosediments. 14C dating provides a chronological framework for geomorphological stability phases and thus, identified soil-forming processes. The first anthropogenic colluvial sediments of the studied archive date to the Early Bronze Age and accumulated in an initial karst depression. Water saturation caused iron reduction of these early infillings. In the pedosediments above, oxidation and iron release are largely related to changes in the parent material. Here, the soil material contains coarse silt indicating an admixture of nearby periglacial slope deposits. Furthermore, fossil root traces point to a longer time with stable conditions, which we interpret as absence of humans or at least an extended period of fallow land. The superimposed sediments from the Urnfield period are more inhomogeneous and consist of material from the eroded agricultural soils of the surrounding. The characteristics of these pedosediments point to intensified human land use. Pedogenic processes such as iron release, reduction of iron, swelling-shrinking, and short-distance translocation of clay intensively overprinted all soil sediments. In this context, micromorphology proved to be an essential tool for the characterization of polygenesis in terms of soil-forming as well as redepositional processes that lead to the formation of these complex archives. The present study reflects a multi-methodological approach to a rather disregarded type of polygenic terrestrial records. It constitutes an example for the investigation of clayey pedosediments in karstic environments under moderate climate in the frame of a prehistoric geoarcheological setting. [ABSTRACT FROM AUTHOR]