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To characterize channel-network morphodynamics and response potential in the Gadria-Strimm basin (14.8 km^2) we conduct a concerted effort entailing: (i) high-resolution mapping of landforms, channel reaches, and sediment sources; and (ii) historical evolution of colluvial channel disturbance through sequential aerial photosets (1945-59-69-82-90-00-06-11). The mapping was carried out via stereographic inspection of aerial photographs, examination of 2.5-m gridded DTM and DSM, and extensive field work. The study area is a formerly glaciated basin characterized by peculiar landform assemblages imposed by a combination of tectonic and glacial first-order structures. The most striking feature in Strimm Creek is a structurally-controlled valley step separating an upper hanging valley, dominated by periglacial and fluvial processes, and a V-notched lower part in which lateral colluvial channels are directly connected to Strimm’s main stem. In Gadria Creek, massive kame terraces located in proximity of the headwaters provide virtually unlimited sediment supply to frequent debris-flow activity, making this sub-catchment an ideal site for monitoring, hence studying the mechanics of these processes. Preliminary results point to a high spatial variability of the colluvial channel network, in which sub-sectors have remained consistently active during the study period while others have become progressively dormant with notable forest re-growth. In an attempt to link sediment flux to topography and substrate type, future work will involve photogrammetric analysis across the sequential aerial photosets as well as a morphometric/geomechanical characterization of the surficial materials.

To evaluate landslide response of mountain drainage basins to forest management we examine a historical inventory in northeastern Vancouver Island. The study area is underlain by extrusive (upper Triassic Karmutsen Formation) and intrusive rocks (Jurassic Island Intrusions). The dataset, compiled via interpretation of sequential aerial photosets, helicopter traverses, and extensive fieldwork, comprises a total of 1961 sediment sources, including 798 field-measured events. Field- and photo-based data cover a time window of approximately 70 years. The effects of forest management on landslide activity are assessed in terms of landslide density, sediment production, landslide geometry, landslide magnitude-frequency relations, topographic conditions of landslide initiation and deposition, and sediment redistribution across landscape components. Results indicate that forest management alters natural landslide dynamics in many respects. Logging-related debris avalanches are typically smaller. Consequently, the magnitude-frequency relation in logged terrain occupies the small-medium magnitude spectrum (< 6000 m3), with frequencies increasing by over an order of magnitude. Lithologic effects on sediment production appear amplified, in that terrain underlain by extrusive rocks become increasingly more unstable than intrusive ones. Analysis of landslide initiation and deposition zones reveals that forest management promotes colluvial aggradation on mid and lower hillslopes and in gullies. This pattern, which accelerates sediment recharge of gully systems, has the potential of increasing the frequency of channelized debris-flows, hence cause an extended period of disturbance, before sediment dynamics recover to pre-logging conditions. The effects of forest clearing on hillslope-channel coupling are composite: in cutblocks the percentage of sediment delivered to streams is reduced by 20-60% whereas road-related landslides are associated with highestconnectivity to streams.

Basin-wide erosion rates can be determined through the analysis of in situ-produced cosmogenic nuclides based on the idea that samples taken at the outlet of a catchment are representative of the entire upstream basin. However, this is only true when a certain number of assumptions are verified. Among the most important assumptions is that denudation rates are uniform through space and time; i.e. the catchment is in cosmogenic steady-state. If this is the case, then the in-going nuclide flux through production is equal to the out-going flux through decay and erosion, and the system is in isotopic equilibrium. When this condition is not matched, the calculation of basin-wide erosion rates through cosmogenic nuclides is subject to the well-mixing conditions of the alluvial sediment in the rivers. Here, we bring a new contribution towards the understanding of sediment mixing effects on in-situ cosmogenic nuclide concentrations in alluvial sediment. We proceed by following the methodology proposed by Binnie et al. (2006), and present the results from a sediment mixing model for a small ( 42 km2) catchment in the Alps. The model results show the importance of the sampling location and of the catchment’s size to have reliable erosion rates. However, the models also highlight the importance of knowing the sediment transfer mechanisms and the processes magnitude. When the transport of sediment mainly occurs through soil creep and shallow landslides, high concentration material is supplied into the fluvial system, increasing the 10Be concentration in the alluvial sediment. Likewise, the high-frequency of mass-wasting processes or the occurrence of sporadic but large-magnitude events, allow the supply of low-concentration sediment that result in a lower cosmogenic nuclide signal in the channels. A strong bias arises for the calculation of basin-wide erosion rates if mass-wasting processes dominate the mechanisms of sediment transfer in the catchment. In this situation the use of cosmogenic nuclides signal results in an over- or underestimation of the erosion rates. Therefore, our results suggest that when using cosmogenic nuclides, the achievement of mixing conditions in alluvial sediment is of primary importance for the correct estimation of the erosion rates and that this latter has to be accurately interpreted when the mixing conditions are unknown or not achieved.

Debris flows are the most efficient processes of sediment transfer from slope base to alluvial fan terminus in mountain drainage basins. To advance current understanding of debris-flow sediment dynamics at the regional scale we analyze historical debris-flow events in 82 basins of the Alto Adige Province, north-eastern Italy. By combining historical information on event-based debris-flow volumetric deposition and high-resolution (LiDARderived) digital topography we (i) identify seasonal trends in debris-flow activity; (ii) characterize the principal topographic conditions at which debris-flow initiation, transportation, and deposition occur; (iii) detail debris-flow sediment transfer at the basin and the regional scales; and (iv) identify lithologic dependences on debris-flow activity. For the first time, we show that basin-wide specific sediment yield describes a negative scaling relation with basin area, which in turn, is modulated by dominant bedrock geology and chiefly by the abundance of glacial and paraglacial surficial materials.

Debris flows are one of the most relevant natural hazards in mountain regions. A combination of structural (e.g. check-dams) and non structural (e.g. warning systems) measures is needed in most cases to reduce debris flow risks, and both benefit from experimental data on debris-flow characteristics. A new experimental site is being equipped in the Autonomous Province of Bolzano (Italy) for both monitoring purposes and testing warning systems. The study site (Gadria basin) is a small channel subjected to frequent debris flows. The overall system includes the following components: 4 rain gauges located at different elevations, 5 radar sensors and 5 geophones, and 3 video cameras and flash lights to record the propagation and the deposition of the debris flow. Transmission of data and alerts from the instruments will use radio technology because GSM coverage is not available in the basin.

Landslides exert prominent controls on the morphology of mountain drainage basins and drive the overall sediment flux across landscape components. In this context, historical landslide inventories are critical for quantifying landslide sediment dynamics through time and assessing relevant contributions to regional sediment budgets. We present an historical inventory that combines the mapping of deep-seated gravitational slope deformations (DSGSD) and shallow landslides in Val di Sole (707 km2), eastern Central Alps, Italy. The study area was selected for two reasons: (i) the composite geological setting including intrusive, metamorphic, and sedimentary formations, which provides the opportunity to evaluate lithological effects on landslide sediment transfer; and (ii) the homogeneous distribution of forest cover, which warrants higher reliability of landslide identification through time. In so doing we avoid areas dominated by large rock walls and sedimentary linkages (e.g., unvegetated talus slopes and screes), typically associated to a chronic flux of colluvial sediment. In these conditions, owing to the subtle contrast between parent material and freshly eroded debris, the identification of fresh landslide scars in sequential photosets is difficult and unreliable. For the same reason, evaluation of the visibility time window for clusters of landslides would become highly uncertain. Data collection involved interpretation of seven sequential photosets (1959, 1969, 1973, 1983, 1996, 2000, 2006) and LiDAR-derived hillshade rasters in conjunction with field measurements. Fieldwork served to measure landslide depths and obtain a volumetric transformation factor for remotely-sensed landslide areas. Inspection of LiDAR hillshades allowed to identify and delineate the perimeter of large slope deformations, otherwise masked by a number of environmental conditions during aerial photo interpretation (e.g., forest cover, shadow, and snow). In the compilation of the inventory, the use of high-resolution hillshades and aerial photos did not prove to be mutually exclusive. If on hand, the former method reduces uncertainty in the identification and delineation of landslide features, on the other it is too expensive to be repeated in time and obtain a multi-temporal dataset. Aerial photographs have limitations in terms of landslide identification, but they are relatively affordable, they have good coverage for large parts of the country since 1950s, and allow to analyse landslide sediment dynamics through time. Results show that the two methodologies should be employed in an integrated approach. We identify a total of 220 DSGSD and 3369 shallow rapid failures that cover an area of 174 km2 and 92 km2 respectively. The corresponding sediment flux exhibits lithologic and topographic controls. Metamorphic, sedimentary, and intrusive terrain are associated with progressively lower rates of sediment production and subsequent delivery to the drainage network. In this context, local confounding modulated by the presence of thick glacigenic deposits is common. Interestingly, lithologies with high density of DSGSD events exhibit higher rates of shallow-rapid failures. This finding suggests that DSGSD events by favouring/preparing the occurrence of shallow rapid failures may control, in an indirect way, landslide sediment flux at the regional scale.

Landscape evolution in mountainous catchments is the result of multiple factors acting at different scales in time and space. The main components affecting basin morphologies are: uplift, glacial cycles, erosion (long timescale), mass movements and cycles of freeze-thaw (short timescale). In this study, we quantify the rates of sediment production and transfer from an alpine catchment in which debris flows are a dominant geomorphic agent. We use cosmogenic nuclides to determine the connectivity between source areas and sinks and to estimate the timescale of sediment production and the fluxes of sediment through the basin. The Zielbach basin consists of a ca. 30 km2-large central basin where cascade and step-pool channels have eroded into the highly fractured and foliated metamorphic bedrock, and a ca. 10 km2-large eastern tributary basin where a network of debris flow channels are perched on a deep-seated sackung. Whereas the central basin shows a poor connectivity between hillslopes and the channel network, the debris flow channels of the eastern tributary basin are closely connected with the bordering hillslopes. In the central basin, the geometry of the channel network is strongly affected by the litho-tectonic fabric as channels parallel the major faults and foliations. In the headwaters, rock glaciers and rock fall deposits tens of meters thick form transverse topographic ridges which retain the sediment in a semi-closed sedimentary traps. Moreover field work and GIS analysis reveal a strong relationship between structural setting and sediments production in which sediment production is high in weakened shear and fault zones. The eastern tributary basin has highly fractured bedrock, partially related to ice retreat after the LGM age. The whole catchment is characterize by a high production of sediments related both to tectonic structure present in the area and to the steep slopes left by the glacial retreat. The geomorphology shows a clear difference between the main basin and the debris flow tributary: the first one is composed by several lateral valley in which sediment can be stored before reaching the channel network, while the tributary is characterize by a long steep slope where the sediments produced can be easily moved down to the fan. 10Be based denudation rates confirm these differences: rates are nearly constant at between 0.3-0.6 mm/yr in the decoupled hillslope-channel segments. This central tributary system of the Zielbach basin can thus be understood as a supply-limited basin with a poor connectivity between sediment sources and drainage network. In contrast, basin averaged denudation rates are high and locally exceed 2.7 mm/yr in the eastern debris flow basin revealing a high connectivity between hillslopes and channel network. Mass balance calculations reveal that individual debris flows contribute up to 90% of the sediment budget of the entire Zielbach basin. These results reveal the importance of stochastic sediment transfer from a high-connectivity tributary on the sediment budget of an entire drainage basin.

In coastal British Columbia, Canada, the glacial palimpsest profoundly affects the geomorphic structure of mountain drainage basins. In this context, by combining remotely sensed, field- and GIS-based data, we examine the scaling behavior of bankfull width and depth with contributing area in a process-based framework. We propose a novel approach that, by detailing interactions between colluvial and fluvial processes, provides new insights on the geomorphic functioning of mountain channels. This approach evaluates the controls exerted by a parsimonious set of governing factors on channel size. Results indicate that systematic deviations from simple power-law trends in bankfull width and depth are common. Deviations are modulated by interactions between the inherited glacial and paraglacial topography (imposed slope), coarse grain-size fraction, and chiefly the rate of colluvial sediment delivery to streams. Cumulatively, departures produce distal cross-sections that are typically narrower and shallower than expected. These outcomes, while reinforcing the notion that mountain drainage basins in formerly glaciated systems are out of balance with current environmental conditions, show that cross-sectional scaling relations are useful metrics for understanding colluvial-alluvial interactions.

Mountain drainage basins are complex systems due to the variety of active geomorphic processes,their interactions at different spatial/temporal scales, and the history of the landscape in terms of climate and tectonic activity. geomorphic coupling. These systems encompass hillslopes dominated by diffusive surface erosion and/or landsliding, steep confined channels dominated by debris flows, and purely alluvial channels flowing along major valley floors where fluvial transport prevails. In this context, the overall process of sediment transfer across landscape components and the associated disturbance-cascade are poorly understood, including the relative importance of one geomorphic process over the others at the watershed scale. In places where hillslopes and channels are well-connected, transport processes overlap, hence strongly interact via geomorphic coupling. The term coupling is used in geomorphology (e.g.,Brunsden and Thornes, 1979; Caine and Swanson, 1989) to indicate the degree of connectivity between hillslope and fluvial processes. Coupled systems exhibit direct colluvial-alluvial interaction, as opposed to decoupled (or buffered) systems, where colluvial sediment inputs do not reach the channel network. Evaluation of degree of coupling is critical to drainage basin sediment dynamics as it controls (i) sediment and process-disturbance cascades, and (ii) in what proportion hillslope denudation rate contributes to drainage basin sediment storage and fluvial sediment yield respectively (e.g., Roberts and Church, 1986; Reid and Dunne, 1996). In geomorphology, the importance of coupling between channels and adjacent hillslopes has been long acknowledged (e.g., Korup, 2005; Fryirs et al., 2007). However, relatively little work has attempted to assess its role in a systematic way. Partly because only very few empirical studies (both field-based and remotely-sensed) have tried to combine hillslopes and channelized landscape components (Benda et al., 1998). In this lecture, we will (i) evaluate how hillslope-channel connectivity can affect channel-reach morphology, channel geometry, and sediment transport potential through published examples and unpublished datasets; (ii) propose future research needs on the topic.

We examine basin-wide colluvial sediment dynamics in the Tsitika and Eve Rivers(about 600 km2), coastal British Columbia, Canada. The colluvial sediment cascade is documented by classifying landslide types, characterizing the dominant sediment sources, and identifying preferential sites of colluvial delivery across the landscape. The study is based on the compilation and analysis of a 70-year landslide inventory. This analysis reveals that open-slope landslides delivering material to seasonal or perennial channels and fluvial terraces are the dominant source-to-sink pathways. This finding indicates high instability of the headwaters drainage network and its ongoing adjustment after generalized sediment recharge occurred in the Last Glacial Maximum (LGM). To quantify interactions between colluvial and fluvial processes the landscape has been subdivided into geomorphic domains, which include planar slopes, unchannelled valleys, erosional (source) and depositional (sink) colluvial channels, as well as fluvial channels. In the study period, landslide activity across landscape components has generated net sediment degradation on planar slopes and source colluvial channels, whereas unchannelled valleys, sink colluvial channels and fluvially-dominated channels have been accumulating material. The newly-developed scaling relation of the landslide sediment yield appears to be controlled by the spatial organization of relict glacial structures. It follows that landslide yield is highest in unchannelled topography, decreases at the scale of channel initiation(drainage area (Ad) about 0.002 km2), and remains constant for scales where source colluvial and hanging fluvial domains overlap (0.002 < Ad< 0.06). Landslide sediment injections start declining consistently beyond areas larger than 0.6 km2 (the scale of relict trough initiation), where fluvial environments are still partially connected to adjacent hillslopes. Cumulative daily yield indicates that landslide sediment redistribution across the landscape is limited to relatively small drainage areas;specifically, 90% of the colluvial load is released at scales smaller than about 0.6 km2. Evaluation of the studied landslide yield trend in conjunction with British Columbia fluvial sediment yield allows us to identify landscape scales of sediment aggradation and degradation, hence to infer preferential scales of contemporary sediment storage.

We examine basin-wide colluvial sediment dynamics through the compilation of a 70-year landslide inventory in mountain environments of coastal British Columbia. In particular, we document the colluvial sediment cascade by characterizing the dominant sediment sources, and by identifying preferential sites of colluvial delivery and storage across landscape scales. Results reveal that open-slope landslides evacuating material to ephemeral or permanent streams and fluvial terraces are the preferential source-to-sink pathways. This pattern suggests high instability of the headmost channel network and its ongoing re-organization after generalized sediment recharge occurred during the last glacial maximum. In the study period, the colluvial sediment budget calculated across geomorphic process domains indicates net volume loss on planar slopes and source colluvial channels, whereas unchannelled valleys, sink colluvial channels and fluvially-dominated channels have been aggrading. In this context, we propose a novel approach to represent colluvial sediment yield as a function of drainage area. This scaling relation appears to be controlled by the spatial organization of geomorphic process domains, as imposed by the morphometry of the glacial palimpsest. It follows that colluvial yield is highest in unchannelled topography, decreases at the scale of channel initiation, and remains constant for drainage areas where source colluvial and hanging fluvial domains overlap. Colluvial sediment injections start declining consistently beyond areas larger than 0.6 km2, where fluvial environments are still partially coupled. Evaluation of the colluvial scaling trend in conjunction with British Columbia fluvial sediment yield, allows us to identify landscape scales of sediment aggradation and degradation, hence to infer preferential scales of contemporary sediment storage.

Landslide magnitude-frequency (LMF) and yield-area relations are examined for evaluating landslide-driven sediment dynamics in the Tsitika and Eve Rivers (612 km{2}), British Columbia. Research methods couple field work and air photo interpretation (API) in a GIS environment. API covers a seventy year time window. Results show that the long history of glacial erosion and the more recent forest management affect contemporary landslide activity in many respects. First, the nature and distribution of Quaternary-derived surficial deposits confounds primary lithologic effects; therefore, topographies underlain by less resistant geology are not typically associated with higher rates of landsliding. Second, the stratifications of LMF by landslide and terrain attributes have allowed detecting for the first time characteristic landslide length scales dependent on (i) movement style (i.e., slide, avalanche, and flow); (ii) type of material mobilized (i.e., bedrock and debris); and (iii) land use (i.e., forest clearing). As a conclusion, landscape bio-morphometric controls override the theoretical self-organized criticality of LMF relations. Third, slope-area analysis of landslide initiation and deposition zones reveals that bedrock landslides dominate the landscape on mountain summits and ridges; these processes deliver material to colluvial channels, in which debris is temporarily stored until remobilization occurs via full-scale debris flows. In undisturbed forest, during the seventy years examined, colluvial activity across geomorphic process domains (seen as sediment reservoirs) has generated net volume accumulation in unchannelled valleys, sink colluvial, and fluvially-dominated channels; in contrast, planar slopes and gullies have been degrading. Logging operations have accentuated aggradation in gullies and in unchannelled topographies. Finally, the area-based scaling relation of landslide sediment yield appears to match the spatial organization of geomorphic process domains. In this context, the contemporary, specific fluvial sediment yield (suspended) of British Columbia exceeds the specific landslide yield for drainage areas comprised between 5 and 50 km{2}. Cumulative daily yield indicates that colluvial sediment redistribution across landscape scales is limited to relatively small drainage areas; specifically, 90% of the colluvial load is injected within contributing area of about 0.6 km{2}.

The spatial distribution of channel types in mountain drainage basins of coastal British Columbia is examined. Using field- and GIS-based data we show that the local channel slope and degree of colluvial-alluvial coupling imposed by the glacial valley morphology dictate the spatial organization of channel-reach morphology. In particular, the glacially-induced channel long profile generates characteristic sequences of channel reaches (with repetitions and inversions) that depart from the downstream succession distinctive of unglaciated mountain streams. For example, the presence of one hanging valley in the river long profile produces and separates two full successions of channel types a headmost one characterized by an ephemeral/seasonal hydrologic regime, and a downstream one, where water runoff is perennial. Exploratory scatter plots indicate that slope, shear stress, and relative roughness ensure best separation between reach types. At a confirmatory level, highest prediction of channel types is achieved by discriminant functions containing the same three variates. Success rates, depending on whether or not boulder-cascade reaches are grouped with step-pools, vary between 89% and 76%. Notwithstanding the glacially-inherited slope and the transient geomorphic dynamics of this landscape, similar to the case of unglaciated mountain streams, channel types are chiefly segregated by local slope (albeit characterized by significantly higher ranges), and to a lesser extent by shear stress and relative roughness. This outcome, while adding considerable strength to prior empirical knowledge, indicates that first-order physical conditions at which distinct channel states form are insensitive to very different landscape structures, hence histories.

We present a new rock glacier inventory compiled for the Orobic Alps (2000 sqkm) and the Livigno Valley (270 sqkm), Lombardy Region, Italy. This effort is part of a larger ongoing project that aims at building a region-wide database of periglacial landforms. The two study areas represent the extremes, in terms of hydro-climatic and physiographic characteristics, within the spectrum of alpine terrain variability in Lombardy. The inventory of the two study areas has been conducted by combining a number of remotely-sensed images with field traverses. Specifically, the interpretation of high-resolution (0,5 x 0,5 m) digital aerial photos flown in 2000, 2003 and 2007 in conjunction with a 2-m DSM (Digital Surface Model), allowed identifying and mapping 416 and 108 rock glaciers in the Orobic Alps and in the Livigno Valley respectively. Measurements and photographs taken during fieldwork provided critical ground control for the validation of data extracted from remotely-based analysis. Attributes for each rock glacier include type (talus-lobate, talus-tongue shaped, debris-lobate, debristongue shaped, and protalus rampart), activity (active/inactive, or relict), minimum and maximum elevation, aspect, slope, geographic location, area, and dominant lithology. Preliminary results sh ow that in both study areas rock glaciers are quite uniformly distributed, with lower spatial densities in the most heavily glacierized areas. This pattern seems to reflect the geomorphological classification between glacial and periglacial environments. In the Orobic Alps, 388 (93%) rock glaciers were classified as relict while only 23 (21%) in Livigno Valley with 75 (89%) active or inactive. The most common rock glacier type in both areas are protalus ramparts (59% in the Orobic Alps and 36% in the Livigno Valley) followed by talus lobate rock glaciers (35% in the former and 32% in the latter). The active/inactive rock glacier’s minimum elevation, often considered discontinuous permafrost’s lower limit, is set a 2747 m a.s.l. in the Livigno Valley and 2386 m a.s.l. in the Orobic Alps. In both study areas, rock glaciers sit at similar slopes (chiefly around 20-25_), face predominantly north sectors, and are composed by metamorphic debris, in agreement with local dominant lithologies. The identification and classification of rock glaciers in Lombardy will form the basis to draft a preliminary regionwide mapping of discontinuous permafrost potential; hence, test and refine available physically-based models of permafrost spatial distribution.

In glaciated British Columbia, Canada, Quaternary climate changes are responsible for profound spatial reorganization of earth surface processes. These changes have left a landscape characterized by topographic anisotropy associated with a hierarchy of glacial troughs. The evolution of formerly glaciated landscapes is examined by considering a set of scaling relations and assessing their departures from known unglaciated trends. Ultimately, the magnitude of these departures should provide a measure of the state of landscape recovery (transience) from glacial disturbance. The set of scaling dependences studied includes slope-area relations, for assessing geomorphic process domains; landslide magnitude-frequency (LMF) and yield-area relations, for evaluating landslide-driven sediment dynamics; and the spatial organization of channel-reach morphology. In addition, along channel long-profiles the scaling between drainage area and channel cross-sectional variates (downstream hydraulic geometry), coarse grain-size fraction, and stream power indices are examined. The methodological approach couples extensive field surveys, GIS-based topographic analysis, air photo interpretation, and multivariate statistical analysis. Slope-area analysis reveals generalized process-form disequilibrium with a mismatch between topographic signatures and currently active geomorphic process domains. At the landscape scale of "source" colluvial channels, the glacial/paraglacial signature commonly overrides that produced by contemporary debris flows. Along the axis of former ice flows, relict glacial cirques introduce a "hanging" fluvial domain at contributing areas as small as 8*10⁻² km² and produce complex channel long-profiles similar to those observed for rivers responding to tectonic forcing. The concept of process domains appears to hold; however, some major glacially-forced modifications in the alluvial-colluvial transition are observed and the definition of a depositional colluvial sub-domain is proposed. Direct spatial scale linkages and generalized departure from unglaciated scaling relations are observed at all levels of investigation. Glacial macro-forms, by imposing local channel gradient and degree of colluvial-alluvial coupling, dictate the spatial distribution of process domains, which in turn affect LMF relations, landslide yield, channel-reach morphology, downstream hydraulic geometry, and stream power. The combination of glacial and post-glacial fingerprints and the effects of ongoing earth surface processes generate a complex landscape whose glacial signatures may persist until the onset of the next ice age.

Episodes of climate change are responsible for profound reorganization of rates and spatial distributions of earth surface processes. In glaciated British Columbia the series of climate changes that occurred during the Quaternary have left a landscape characterized by a peculiar hierarchy of topographic anisotropies. Currently, fluvial and hillslope processes dominate the landscape, and are slowly reshaping these anisotropies. By means of extensive channel surveys, air photo interpretation, and GIS analysis we extracted slope-area transects along the main stem of drainage basins - area ranging between 1 km2 and 50 km2 - located in three different physiographic regions of British Columbia. Results display generalized process-form disequilibrium, where topographic signatures do not match with currently active geomorphic process domains. The landscape has not recovered yet from past glacial perturbations, accordingly, the combination of glacial legacies and the effects of ongoing earth surface processes generate a more complex geomorphic picture than that described elsewhere for unglaciated mountains. This emphasizes the importance of climatic and geomorphic history in interpreting contemporary landscape dynamics.

Magnitude-frequency analysis is used here as a statistical method to quantify the erosion produced by rapid shallow failures in a glaciated basin of coastal British Columbia. Coupling air photo and ground-derived data we prove that the deviation from power-law distribution observed for small magnitude is an artefact of detection deficiencies. However, the total distribution shows to be not sensitive to the occurrence of small mass failures and total erosion remains well represented in the API-derived data. Our dataset also denotes a real deviation from simple scaling at much higher magnitudes, the cause of which is currently under investigation.

Rock avalanches are large flow-like movements of fragmented rock that can cause extensive and rapid topographic changes, for which very few quantitative data are available. This paper analyses the geomorphological and hydrological impact of the 3 million m 3 Thurwieser rock avalanche (2004, Italian Central Alps) by using Terrestrial Laser Scanner, airborne Lidar and GNSS data collected from 2005 to 2014. Sediment yield with respect to the normal valley regime, the dynamic and mass balance of affected glaciers, and the reorganization of superficial and groundwater flow networks are quantified. In the middle portion of the avalanche deposit, a natural sediment trap collected sediments from a new stream channel developed along the upper portion of the deposit and from a lateral drainage basin. This made possible to assess the 10-year impact of the rock avalanche on the sediment yield, which increased from about 120 to about 400 t km − 2 ·a − 1 . The rock avalanche partially covered a glacier with a shallow debris layer that acted as a thermal insulator, limiting ice ablation and producing a 10-m high scarp between the free surface of the glacier and the debris-covered portion. A reduction of 75% of ice ablation was observed due to thermal insulation. The rock avalanche filled a tributary valley, splitting the original drainage basin in two. Under ordinary flows, seepage occurs within the avalanche deposit along the old valley axis. During high flow conditions, a new stream channel is activated along the middle and lower margin of the deposit, which has produced a new alluvial fan on the main valley floor. The fan evolution is described up to the present volume of about 2000 m 3 .

We examine preliminary data from a landslide inventory that combines the mapping of landslides and deep-seated gravitational slope deformations (DSGSDs) in Val di Sole, eastern Central Alps, Italy. Landslide identification and classification was conducted via interpretation of sequential airphotos (API), LiDAR shaded-relief rasters. Landslide geometries were measured in the field for a sample of events. Seeking to evaluate landslide-driven sediment flux, we consider landslides as sediment sources and we classify them into rapid, full-mobility failures and slow, partial-mobility ones. The corresponding sediment flux, solely associated with rapid failures, exhibits clear lithologic controls, with metamorphic rocks displaying markedly higher landslide activity. DSGSDs occur exclusively in metamorphic terrain and landslides tend to cluster around them. Accordingly, these large-scale slope deformations could play a prominent role in modulating the contemporary landslide sediment flux. In the compilation of the inventory, the use of LiDAR and airphotos did not prove to be mutually exclusive. We recommend the two methodologies be employed in an integrated framework. © Springer-Verlag Berlin Heidelberg 2013.