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The formation of snow avalanches is controlled by the complex interaction between terrain characteristics, snowpack and meteorological conditions. Accordingly, snow avalanches exhibit a high sensitivity to climatic variations. This study focuses on the possible effects of climatic variations on snow avalanche activity within one of Norway’s most snow avalanche-prone areas. We have statistically analyzed long-term homogenized meteorological data from seven official meteorological stations, three of them with a long-term record of 120 years (1896-2015). In addition, gained results and insights from a four-year (2009-2012) high-resolution snow avalanche monitoring investigation conducted in the same study area are incorporated. Potential effects and overall implications of a changing snow avalanche activity are discussed. Statistical analyses show an increasing trend for both air temperature and precipitation with an accelerated increase for the last 30 years for the core winter period. A tendency for a relationship between a positive North Atlantic Oscillation index and higher precipitation sums during winter could be detected. Magnitude-frequency analyses of monthly precipitation sums for the winter period exhibit an increase of precipitation especially during the last three decades with the tendency that more precipitation can be expected in March and February. An increase of the monthly precipitation sums during the winter period may lead to a generally higher snow avalanche frequency. Due to more frequent periods with air temperatures close or above the freezing point during the winter period, the probability of wet snow avalanches and slush flows will increase. [ABSTRACT FROM AUTHOR]

Based on existing meteorological records, increases of annual air temperatures, annual precipitation sums, annual wind speeds, and of the frequencies and intensities of heavy rainfall and storm events in Norway are postulated. From a process-geomorphological point of view it is of growing importance to obtain an improved knowledge of the complex relationships between contemporary geomorphologic processes, vegetation cover and present-day climatic conditions to arrive at more realistic assessments of possible geomorphic effects of ongoing and future climate changes. This study analyzes the morphoclimate of a boreal-oceanic drainage basin system in central Norway and presents aspects of the contemporary wind, air temperature and precipitation regimes that control the type, frequency, intensity and duration of relevant denudational surface processes operating in the area. The work is based on statistical analyses (magnitude-frequency analyses) of existing meteorological data and process-geomorphologic field work conducted over a five-year investigation period (November 2011-October 2016) in the Homla drainage basin (156.3 km2) in central Norway. Due to the distinct characteristics of the present-day morphoclimate, runoff occurs year-round and chemical denudation clearly dominates over mechanical denudation. Mechanical denudation is strongly event-controlled and the highest share of annual fluvial transport occurs in May during the peak of spring snowmelt. Both chemical denudation (12.1 t km−2 yr−1) and mechanical denudation (3.6 t km−2 yr−1) are of low intensity which is explained by the cool climate combined with a nearly closed and continuous vegetation cover, small thicknesses of sedimentary covers, a high weathering resistance of the predominant bedrock and only low topographic relief in the upper parts of the Homla drainage basin. It is expected that the postulated changes of the wind, air temperature and precipitation regimes will lead to increasing chemical and mechanical denudation rates in the study area. [ABSTRACT FROM AUTHOR]

The various mountainous landscapes of Iceland, Sweden and Norway are characterized by Pleistocene glaciations and, connected to this, a dominance of glacially sculpted landforms like U-shaped valley systems, cirques, lakes and hanging valleys. The thickness of glacigenic deposits from this period can vary significantly across different mountain landscapes. In consideration of such legacies, these formerly glaciated landscapes today can be considered at a unique stage of readjustment (recovery) with respect to spatial organization of currently active geomorphic process domains and the magnitude and patterns of sediment storage and sedimentary fluxes. Accordingly, the postglacial relief development in these landscapes is controlled by a wide range of environmental drivers. This study focuses on trends of postglacial relief development in five selected valley systems in formerly glaciated mountain landscapes in eastern Iceland, northern Sweden and western Norway. The selected valley systems Austdalur (23.0 km2) and Hrafndalur (7.0 km2) in eastern Iceland, Latnjavagge (9.0 km2) in northern Sweden, and Erdalen (79.5 km2) and Bødalen (60.1 km2) in western Norway are considered to be representative valley systems for the respective mountain regions they are situated in. Our investigations include a quantitative compilation of contemporary mass transfers in the five valley systems, the quantitative analysis of current Ho/Hi index values for the slope systems in the valleys as well as a semi-quantitative description of changes of valley cross-sectional and longitudinal profiles since deglaciation. As a result, all U-shaped valley systems are characterized by an ongoing valley widening due to the continuing retreat of the existing rock-walls. However, the different valley systems show significant variations in the intensity of slope-channel coupling, in their slope and valley-floor storage behavior, in the development of their longitudinal valley profiles, and in the general intensity of postglacial relief modification. Accordingly, trends of postglacial relief development appear to be rather complex in the different mountain landscapes. It is found that the specific characteristics of the glacially sculpted and inherited valley morphometries are the most important control of the detected differences in slope-channel coupling, storage behavior and longitudinal valley profile development. Lithology and the given weathering resistance of the predominant bedrock are most important for the general intensity of postglacial relief modification. Apart from Hrafndalur which is characterized by rhyolites with particularly low weathering resistance, postglacial modification of the inherited glacially sculpted valley morphometries is altogether little and the landforms have not yet adjusted to the geomorphic surface processes that have been operating under postglacial morphoclimates. [ABSTRACT FROM AUTHOR]

Contemporary fluvial bedload transport rates are still very difficult to measure and, as a result of this, in many sites only quantitative data on suspended and solute transport are included in sediment budget studies carried out for defined drainage basin systems. The presented analysis of fluvial bedload dynamics in different defined subsystems of the glacier-connected Erdalen (79.5 km 2 ) and Bødalen (60.1 km 2 ) drainage basins in the steep fjord landscape of western Norway provides insights into (i) detectable relevant sediment sources, (ii) instream channel storage of bedload material, (iii) spatiotemporal variability and controls of bedload transport rates and bedload yields, and (iv) the absolute and relative importance of fluvial bedload transport within the sedimentary budgets of these steep cold climate mountain valleys. Rockfalls, snow avalanches, stream channel bank erosion, and fluvial transfers through small tributaries draining slope systems are relevant sediment sources for fluvial bedload transport in the main stream channels, whereas the main outlet glaciers in both drainage basins are not of importance as all bedload material delivered directly from these outlet glaciers is trapped within proglacial lakes. Narrow valleys within both drainage basin systems are characterized by a higher intensity of slope-channel coupling and display higher rates of sediment supply from slopes into the main stream channels than wider valleys. Snow avalanches are the most important sediment source in Erdalen, whereas fluvial transfers through small tributaries followed by snow avalanches are most important in Bødalen. Longer term, instream channel storage is not of great importance in the steep Bødalen drainage basin but currently plays an important role within the Erdalen drainage basin, which is characterized by a stepped longitudinal main valley bottom profile favoring deposition of bedload material within less steep main channel reaches. The mean annual bedload yields (2010–2013) are 2.4 t km − 2 y − 1 for the entire Erdalen and 13.3 t km − 2 y − 1 for the entire Bødalen drainage basin, which are comparably low values for steep and partly glacierized drainage basin systems. Because of supply-limited conditions, the intensity of fluvial bedload transport is generally much more related to the availability of sediments than to channel discharge. Fluvial bedload transport accounts for about one-third of the total fluvial transport and accordingly plays an important role within the sedimentary budgets of both drainage basin systems. [ABSTRACT FROM AUTHOR]

Abstract: The timing and rate of fluvial bedload transport are of central importance within sediment budget studies and in many applications in river science and engineering. During the years 2010, 2011 and 2012 detailed field measurements with portable impact sensors as a non-invasive technique for indirectly determining fluvial bedload transport intensity were conducted in two instrumented and supply-limited drainage basin systems (Erdalen and Bødalen) in the fjord landscape in western Norway. Additional field measurements with portable impact sensors were carried out in 2010 and 2011 in selected transport-limited fluvial systems in the Coast Mountains of western Canada. The collected impact sensor field data were calibrated with laboratory flume experiments. The data from the impact sensor field measurements in western Norway and the flume experiments were combined with field data from continuous discharge monitoring, repeated surveys of channel morphometry and sediment texture, particle tracer measurements, Helley–Smith samplings, underwater video filming and biofilm analyses. The combination of methods and techniques applied provides insights into the temporal variability and intensity of fluvial bedload transport in the selected mountain streams: (i) in the transport-limited systems with generally high bedload transport rates during high discharge and with bedload material moving in clusters over the impact sensor plates, impact sensor data (based on a 1s measuring interval) provide the opportunity to detect the start and end of bedload transport, thus to identify discharge thresholds for sediment entrainment, and to roughly estimate the intensity and relative intensity of change of bedload transport during the measuring period; (ii) in the supply-limited systems with low bedload transport rates and bedload components moving separately (as single particles) over the impact sensor plates, impact sensor data (with a 1s measuring interval) allow the detection of the start and end of transport of bedload components >11.3mm, thus the identification of discharge thresholds for possible entrainment of particles, the quantification of the number of particles >11.3mm moving over the impact sensor plates during the measuring period, the rough estimation of grain sizes of the particles moving separately over the impact sensor plates, and the calculation of the total mass of the bedload material >11.3mm moving over the impact sensor plates during the measuring period; (iii) when combined with other methods and techniques (Helley–Smith sampling, particle tracer measurements, biofilm analyses, underwater video filming) which provide information on the active bedload transport channel width, on discharge thresholds for possible entrainment of particles of different grain sizes, and on transport rates of bedload material <11.3mm, total rates of fluvial bedload transport, covering all given grain sizes of the bedload material, can be calculated for the supply-limited mountain streams with generally low bedload transport. The higher measured annual bedload yield in Bødalen (13.6tkm−2 yr−1) compared to Erdalen (2.6tkm−2 yr−1) reflects a higher level of slope–channel coupling in Bødalen than in Erdalen. [Copyright &y& Elsevier]

Snow avalanches are common phenomena in Norway. Controlling factors of snow avalanche distribution and activity, and the relative importance of snow avalanches regarding contemporary sedimentary mass transfers were explored within two steep, parabolic-shaped and glacier-connected tributary valleys (Erdalen and Bødalen) in western Norway. Mapping of distribution, extent and the entire path lengths of snow avalanches was combined with spatial data analysis (GIS and DEM computing) of morphometric controls. The timing and frequency of snow avalanches were explored by correlating meteorological data with high-resolution monitoring data of snow avalanche events. Sediment masses annually transferred by snow avalanches along hillslopes and from hillslopes into stream channels were estimated. A high inter-annual variability of avalanche activity and a wide spectrum of avalanche sizes and types ranging from small to extreme-sized events were found for the four-year investigation period 2009–2012. Spatial distribution of snow avalanches is governed by the topographical factors valley orientation, slope aspect, relative slope height and rockwall morphometry whereas timing and frequency of snow avalanches are controlled by snowfall intensity, periods with strong winds combined with a prevalent wind direction or sharp air temperature changes within short time periods. Snow avalanches represent one of the dominant denudational processes and have a high relative importance regarding sedimentary mass transfers within the two mountain valleys Erdalen and Bødalen in western Norway. [ABSTRACT FROM AUTHOR]

The role of hillslopes, functioning as the key elements for sediment production, storage and transfers, is particularly important within headwater systems in cold climate mountain landscapes that are considered to react sensitively to climate change and human impact. Environmental controls, rates and sedimentary mass transfers of the contemporary slope processes were explored within the headwater systems of the parabolic-shaped and glacier-connected Erdalen and Bødalen drainage basins in western Norway. The identified relevant contemporary processes in both drainage basins include rockfalls and boulder falls; snow avalanches; slush flows; debris flows; slow mass movements and creep processes; wash and chemical denudation; and fluvial transport of solutes, suspended sediments and bedload. These denudational processes were analyzed based on an extensive geomorphic monitoring program conducted over a period of four years (2009–2012) combined with detailed geomorphological mapping and in-depth studies of the most important slope processes. A range of different monitoring and field techniques was applied. The results show that the intensity of contemporary denudational processes in Erdalen and Bødalen is rather low and appears to be in a range of magnitude comparable to a number of other cold climate environments situated in the higher latitudes of the northern hemisphere. The present-day spatio-temporal pattern of the denudational slope processes occurring in the headwater systems is controlled by a complex combination of meteorological and morphometric factors. A comparison of the different denudational slope processes according to their annual mass transfers reveals the highest relative importance for rockfalls, snow avalanches, slope wash and chemical slope denudation in Erdalen, as well as for rockfalls, chemical slope denudation, snow avalanches and debris flows in Bødalen. The revealed differences between the single headwaters regarding the absolute and relative importance of the denudational slope processes are seen as a consequence of the different glacially inherited valley morphometries. However, due to the generally low process intensities, the postglacial modification of the inherited glacial relief is altogether minor in both valleys. [ABSTRACT FROM AUTHOR]

Abstract: Large areas of the Norwegian fjord landscapes are covered by hillslopes that reflect the influence of glacial inheritance from the Last Glacial Maximum (LGM). The focus of this paper is two-fold: (1) analyze the spatio-temporal variability of relevant denudational slope processes and process intensities over the Holocene; and (2) detect Holocene modification of the glacial valley morphometry. Research was performed on hillslope systems within two steep, parabolic-shaped and glacier-fed tributary valleys, Erdalen and Bødalen located on the western side of the Jostedalsbreen ice cap in western Norway. Orthophoto delineation, high resolution mapping (TLS), detailed geomorphological information and spatial data analysis were combined with dating techniques and geophysical investigations. Calculated Holocene rockwall retreat rates at selected slope test sites range from 0.38 to 0.67mmyr−1, with a mean value of 0.53mmyr−1. Slightly higher values were found in Erdalen, with a mean rockwall retreat rate of 0.57mmyr−1 compared to 0.50mmyr−1 in Bødalen. Valley-wide Holocene rockwall retreat rates of 0.38–0.50mmyr−1 are consistent with other estimates of Holocene rockwall retreat rates in cold mountain environments. It is shown that the glacial inheritance of topography is the most important factor controlling valley development since the LGM and that sediment storage capacity is primarily conditioned by valley morphometry. Compared to contemporary rates, the results indicate enhanced denudation activity and intensity immediately following deglaciation and during the ‘Little Ice Age’. The overall tendency of landscape development is postglacial widening of the parabolic-shaped valley morphometry through rockwall retreat with associated debris accumulation beneath rockwalls. As a result, the glacially sculpted topography has not yet adapted to denudational processes acting under Holocene environmental conditions. [Copyright &y& Elsevier]

Abstract: This paper focuses on the influence of the “Little Ice Age” (LIA) glacier advance on hillslope morphometry and development in selected U-shaped and (para)glacial tributary valleys, which are still occupied in their upper parts by outlet glaciers of the Jostedalsbreen ice cap in Western Norway. Especially the morphometric influences and geomorphic consequences of the LIA glacier advance on the development of the valley-side hillslope systems and associated denudative processes are assessed by comparing hillslope systems located inside and outside of the LIA glacier maximum extent. The process-based approach applied includes orthophoto- and topographical map interpretation as well as hillslope profile surveying in field for morphometric analyses and detailed geomorphological mapping for process analyses. In addition GIS and DEM computing as well as geophysical measurements (georadar) for storage analyses are performed. It is found that hillslopes inside the LIA glacier limit have steepened lower hillslope segments due to a negative sediment net balance of removal and deposition of material by the advancing LIA glacier front. There are significant differences in the present-day slope debris thickness and composition between hillslopes inside or outside the LIA glacier limit. Slope debris from hillslopes inside the glacier maximum extent are clearly less thick and display a different internal structure originating from a combination of debris from gravitational processes and reworked modern glacial deposits. Compared to that slope debris covers on hillslopes outside the LIA glacier limit are in general noticeable thicker and less influenced by glacial deposits. The combined effects of modified slope morphometry and altered composition of material covering lower hillslope segments have generated a higher intensity of post-LIA denudative hillslope processes. [Copyright &y& Elsevier]

Abstract: This study conducted over an investigation period of six years (2004–2010) focuses on spatial variation in chemical components of drainage water from sub-areas within a confined drainage basin of 79.5km2 (Erdalen drainage basin, inner Nordfjord, western Norway) for detection of spatial diversity and relation to environmental factors. The Erdalen drainage basin is homogenously composed of gneisses, which is reflected in a homogenous relative (as a percentage) chemical composition of surface water across the entire drainage basin system. At the same time, the mean annual TDS values of surface water sampled in creeks draining defined subsystems within Erdalen show a rather high spatial variability. The main controls of this spatial variability are (i) differences in slope deposit/regolith thickness, (ii) differences in slope angle, (iii) differences in areal regolith cover, (iv) differences in vegetation cover, (v) differences in snow cover and ground frost conditions, and (vi) differences in elevation (ma.s.l.). Altogether, the mean annual TDS values in Erdalen are rather low, which can be explained by (i) the shallow thickness of regolith across the very steep drainage basin, (ii) the small percentage of surface areas showing a significant cover of regolith, (iii) the cool climate in the fjord landscape of western Norway and (iv) the weathering resistance of the predominant gneisses within Erdalen. The annual chemical denudation rates in Erdalen are in a similar range of magnitude to rates published for numerous other cold environment catchments worldwide. Despite the rather low mean annual TDS values, chemical denudation is a comparably important and spatially very variable denudational process and should therefore not be neglected when studying slope development as well as slope- and catchment-wide denudation rates and mass budgets in this kind of steep, mountainous cold climate drainage basins. [Copyright &y& Elsevier]

A study was carried out of the subrecent sediment budget of a braided sandur system in a U-shaped valley linked to the Jostedalsbreen ice field in Nordfjord, in Western Norway. Special focus was on (i) the detection of different zones with negative, positive or balanced subrecent (following the Little Ice Age advance) sediment budget within the braided sandur system, (ii) the identification of sediment sources upstream of Sandane and from the slope systems to both sides of the braided sandur system, and (iii) the analysis of the subrecent sediment budget of the entire Sandane system. A combination of methods was applied in the analysis. The upstream part of Sandane was found to be characterised by a negative subrecent sediment balance, with erosion of coarse sediments from the Little Ice Age advance. In comparison, the downstream parts of Sandane have a balanced to slightly positive subrecent sediment budget, with formation of younger flood sediments and more stable channels. Thus, the subrecent sediment budget of Sandane appears to be slightly negative. Present-day coupling of slope and fluvial systems is limited and only a rather small amount of sediments is directly transported from the slopes into the braided sandur. In sum, fluvial sediment transport following the Little Ice Age period appears to be supply-limited. [ABSTRACT FROM AUTHOR]

Contemporary hillslope processes are extremely varied and are driven by a number of diverse physical, chemical, and biological processes. These processes span a wide range of spatial and temporal scales and are considered to react sensitively to climatic changes, anthropogenic impacts and other disturbances.We present ongoing GFL research activities focussing on environmental drivers of rockwall retreat, and denudational hillslope processes in a cold climate mountain environment (western Norway) and in a Mediterranean mountain setting (eastern Spain). In detail, we explore the influence of (i) lithological and structural characteristics, (ii) the rockwall temperature regime and (iii) the connected relative importance of physical-, chemical- and biological processes on weathering and resultant morphologies under these two contrasting climates. Special focus is on possible effects of ongoing and accelerated climate change and on the question how these effects differ under the two distinct climates. Our research is conducted on selected hillslope systems within two tributary valleys (max. elevation 2083 m a.s.l.) located on the western side of the Jostedalsbreen ice cap within the fjord landscape of western Norway. The lithology consists primarily of Precambrian granitic orthogneisses. The climate (slightly above sea level) is cool temperate oceanic with a mean annual air temperature of ca. 6°C and an annual precipitation sum of 1100 mm. January and February are the coldest months with mean monthly air temperatures below 0°C. Higher elevations are characterized by a distinct winter frost regime and a several months lasting closed snow cover. Maximum summer temperatures (June, July) are rarely exceeding 25°C but rockwalls having a favourable exposition can receive a rather high solar radiation. The selected hillslope systems in eastern Spain (Calpe) are located within the Sierra de Bernia mountains (max. elevation 1126 m a.s.l.) which consist of glauconitic and bioclastic marine limestones with alterations of marl. The area is characterized by a mild Mediterranean climate with a mean annual air temperature of ca. 18°C and an annual precipitation sum around 400 mm (slightly above sea level). During the coldest months (January, February) it can be comparably cold even with frost and snow in the mountains although they are situated close to the coast. In contrast, maximum summer temperatures (July, August) can easily exceed 30°C and south-facing rockwalls are exposed to a high solar radiation. Our investigations encompass detailed geological and geomorphologial mapping, the identification and monitoring of the most relevant hillslope processes in combination with detailed statistical analysis of meteorological data. The monitoring programme includes installed nets for collecting freshly accumulated rockfall debris, installed tracer lines and remote time-laps cameras for monitoring various mass transfers as well as near-surface and surface rockwall temperature sensors for monitoring the thermal rockwall regime.An improved and more comprehensive understanding of how different environmental factors interact and control hillslope processes under two contrasting and changing climates is expected to be essential for predicting possible effects of ongoing climate change in sensitive mountain environments. [ABSTRACT FROM AUTHOR]

Climate change, human activities and other perturbations (like, e.g., fires, earthquakes) are likely to influence existing patterns of weathering, erosion, transport and deposition of material across defined landscape components and units. While it is still a challenge to develop an improved understanding of how such changes interact and affect slope and fluvial processes, the connectivity within landscapes and between slope and fluvial systems, as well as contemporary denudation rates, source-to-sink fluxes, and sedimentary budgets, this kind of quantitative analyses promise to be an efficient framework to assess the impact of environmental changes and disturbances to sediment dynamics and to evaluate landscape sensitivity. The current knowledge on drivers and rates of contemporary sediment dynamics and denudation forms the basis for understanding and predicting the consequences of ongoing and accelerated environmental changes. Ongoing GFL research activities on drivers and quantitative rates of contemporary sediment dynamics and chemical and mechanical denudation in selected drainage basin systems in central Norway and eastern Spain are presented. The upper Driva drainage basin in central Norway (Oppdal) is situated in a cold climate and mountainous environment, has year-round discharge with a nival runoff regime, and the temporal variability of sediment transfers, runoff and fluvial transport are largely controlled by thermally and/or pluvially determined events. Our investigations include detailed geomorphological and permafrost mapping combined with the detailed statistical analysis of meteorological data and the continuous observation and year-round monitoring of sediment transfers, runoff and fluvial transport using a range of different techniques in different selected tributary systems of the upper Driva drainage basin. The Pou Roig and Quisi catchment systems in eastern Spain (Calpe) are located in a Mediterranean, partly mountainous and/or anthropogenically affected environment. Sediment transfers, the intermittent runoff and fluvial transport are almost entirely controlled by pluvial events. Our investigations in this study area include detailed geomorphological mapping combined with the detailed statistical analysis of meteorological data and the observation and monitoring of sediment-transfer, runoff and fluvial transport events using a combination of different observation, monitoring and sampling techniques. Our results on controls and the spatio-temporal variability of chemical and mechanical denudation within the two study regions contribute to an advanced understanding of key drivers and rates of contemporary sediment dynamics and denudation in different morphoclimatic environments, and provide the basis for improved predictions of possible effects of climate change and anthropogenic impacts on contemporary denudation rates in different morphoclimatic regions. [ABSTRACT FROM AUTHOR]

Abstract: This paper analyses with the help of tree-ring studies the recurrence of extreme snow avalanches in a path situated in the upper Bødalen valley and originating from an outlet glacier of the Jostedalsbreen ice cap. By analysing tree-ring patterns of 91 trees, four extreme snow-avalanche events, extending over the entire valley floor and up to a distance of 800m from the foot of the slope, are clearly highlighted during the 20th century and at the beginning of the 21st century. Return periods of 15 to 20years for the most extreme events are extracted from the analyses, and recurrence intervals of 10 to 15years for avalanches presenting distinct deposition lobes uphill of the distal torrent. Results obtained by tree-ring analyses are successfully compared with available documents at different spatial and temporal scales. Rock-face snow-avalanche occurrences in the area, of small to medium size, are associated with heavy wintry precipitation combined with strong winds. However this normal situation is not valid for extreme snow avalanches crossing the path investigated in the paper, which result from the outlet glacier located in the starting zone; this glacier commands spatial and inter-annual variations of snow accumulation in the departure zone. [Copyright &y& Elsevier]

The effects of human activity on geomorphic processes, particularly those related to denudation/sedimentation, are investigated by reviewing case studies and global assessments covering the past few centuries. Evidence we have assembled from different parts of the world, as well as from the literature, show that certain geomorphic processes are experiencing an acceleration, especially since the mid-twentieth century. This suggests that a global geomorphic change is taking place, largely caused by anthropogenic landscape changes. Direct human-driven denudation (through activities involving excavation, transport, and accumulation of geological materials) has increased by a factor of 30 between 1950 and 2015, representing a ten-fold increase of per capita effect. Direct plus indirectly human-induced denudation (triggered by land surface alteration) is presently at least one order of magnitude greater than denudation due to purely natural processes. The activity of slope movements, which represent an important contribution to denudation, sediment generation and landscape evolution, also shows a clear intensification. Frequency of hazardous events and disasters related to slope movements (an indirect measure of process frequency) in specific regions, as well as at continental and global levels, has grown considerably, in particular after the mid-twentieth century. Intense rainstorm events are often related to slope movement occurrence, but the general increasing trend observed is not satisfactorily explained by climate. Sedimentation has augmented considerably in most regions and all kinds of sedimentation environments. Although the link between denudation and sedimentation is not direct and unequivocal, it is safe to assume that if sedimentation rates increase in different regions during a given period, denudation must have increased too, even though their magnitudes could be different. This augmentation, particularly marked from the second half of the last century onwards, appears to be determined mainly by land surface changes, in conjunction with climate change. The changes observed suggest: a) there is evidence at a global scale of a growing response of geomorphic systems to socio-economic drivers, being Gross Domestic Product density, a good indicator of the human potential to cause such impacts; b) Land use/cover changes enhance effects of climate change on global denudation/sedimentation and landslide/flood frequency, and appear to be a stronger controlling factor; c) Our findings point to the existence of a global geomorphic change. This manifestation of global change is especially evident since the "great geomorphic acceleration" that began in the middle of the 20th century, and constitutes one of the characteristics of the proposed Anthropocene. [Display omitted] • Technological denudation is presently over one order of magnitude greater than natural denudation. • Increasing trends of slope movements observed not satisfactorily explained by climate • Strong sedimentation increase in most regions and all kinds of sedimentation environments. • Increases described, particularly clear since mid-20th century, respond to land surface changes. • A global "great geomorphic acceleration" is taking place and characterizes the Anthropocene. [ABSTRACT FROM AUTHOR]