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Drainage basins of the Northern Apennines, particularly in the clayey settings, bear among the highest rates of landsliding worldwide. A history of major land cover changes has left a landscape characterized by sparse, coppice-managed forest, transitional shrubs, and actively eroding badlands. Historical trends of landslide occurrence are examined in the Sillaro River basin (139 km2) in relation to land cover and climatic changes. To this purpose we have compiled a multi-temporal (1954–2018) landslide inventory (n = 1164) across twelve sequential photo sets that bears decadal (7- to 15-yr) and finer (2- to 6-yr) temporal resolution respectively before and after 1996. To account for changes in meteorological forcing, we examine: (i) the total annual precipitation (PRCPTOT); (ii) the annual maximum daily precipitation (RX1day); and (iii) the precipitation fraction (R99pTOT) due to extremely wet days. We find that landslide activity is strongly controlled by lithology, with landslide densities in claystones 3-to-4 times higher than in marl-sandstone alternations. This difference is chiefly associated with badlands, which are the most active land cover type and where new scars at a site could recur up to nine times. To evaluate the influence of varying temporal resolution on inventory completeness, hence on inference about land cover and climatic effects, we constrain the time scales of landslide visibility and assess the relative rates of undersampling. We find that visibility functions decline non-linearly with time, and that an inventory compiled at 5-year resolution would be missing up to 20 % of the landslide scars, with the size of an additional 27 % that would be underestimated due to revegetation. Overall, detection of entire landslide scars, which varies with land cover, becomes rare after 13 years in transitional shrubs, and after 17 years in badlands and managed forest. The historical analysis shows that landslide count: (i) increases in 1955–1976, a period o

This doctoral thesis focuses on the study of historical shallow landslide activity over time in response to anthropogenic forcing on land use, through the compilation of multi-temporal landslide inventories. The study areas, located in contrasting settings and characterized by different history of land-cover changes, include the Sillaro River basin (Italy) and the Tsitika and Eve River basins (coastal British Columbia). The Sillaro River basin belongs to clay-dominated settings, characterized by extensive badland development, and dominated by earth slides and earthflows. Here, forest removal began in the Roman period and has been followed by agricultural land abandonment and natural revegetation in recent time. By contrast, the Tsitika-Eve River basins are characterized by granitic and basaltic lithologies, and dominated by debris slides, debris flows and debris avalanches. In this setting, anthropogenic impacts started in 1960’s and have involved logging operation. The thesis begins with an introductory chapter, followed by a methodological section, where a multi-temporal mapping approach is proposed and tested at four landslide sites of the Sillaro River basin. Results, in terms of inventory completeness in time and space, are compared against the existing region-wide Emilia-Romagna inventory. This approach is then applied at the Sillaro River basin scale, where the multi-temporal inventory obtained is used to investigate the landslide activity in relation to historical land cover changes across geologic domains and in relation to hydro-meteorological forcing. Then, the impact of timber harvesting and road construction on landslide activity and sediment transfer in the Tsitika-Eve River basins is investigated, with a focus on the controls that interactions between landscape morphometry and cutblock location may have on landslide size-frequency relations. The thesis ends with a summary of the main findings and discusses advantages and limitations associated with th

Questo lavoro di tesi è finalizzato allo studio delle morfodinamiche fluviali in ambiente montano, in risposta a forzanti antropiche e naturali. In particolare, si prendono in considerazione sistemi Appenninici (i.e., Fiume Santerno) e Alpini (i.e., Rii Grigno, Tolvà e Ussaia), integrando due approcci che si sviluppano su scale spazio-temporali differenti. Nel caso Appenninico vengono esaminati i cambiamenti planimetrici dell’alveo attivo del Fiume Santerno in risposta ad impatti antropici, quali l’estrazione di inerti in alveo, la costruzione di opere idrauliche e l’alterazione di uso del suolo a scala di bacino. Nei tre casi Alpini, che si differenziano in termini di forzante idro-meteorologica ed apporto di sedimento da monte, si è valutato il trasporto solido di fondo (bedload transport) mediante tecnologia RFID., The present study refers to the fluvial morphodynamics study in mountain environments by a multi-scale approach.

Questo lavoro di tesi è finalizzato allo studio delle morfodinamiche fluviali in ambiente montano, in risposta a forzanti antropiche e naturali. In particolare, si prendono in considerazione sistemi Appenninici (i.e., Fiume Santerno) e Alpini (i.e., Rii Grigno, Tolvà e Ussaia), integrando due approcci che si sviluppano su scale spazio-temporali differenti. Nel caso Appenninico vengono esaminati i cambiamenti planimetrici dell’alveo attivo del Fiume Santerno in risposta ad impatti antropici, quali l’estrazione di inerti in alveo, la costruzione di opere idrauliche e l’alterazione di uso del suolo a scala di bacino. Nei tre casi Alpini, che si differenziano in termini di forzante idro-meteorologica ed apporto di sedimento da monte, si è valutato il trasporto solido di fondo (bedload transport) mediante tecnologia RFID., The present study refers to the fluvial morphodynamics study in mountain environments by a multi-scale approach.

Indices of connectivity are critical means for moving from qualitative to (semi-)quantitative evaluations of material (e.g., water, sediment and nutrients) transfer across the building blocks of a terrestrial system. In geomorphology, compared to closely related disciplines like ecology and hydrology, the development of indices has only recently started and as such presents opportunities and challenges that merit attention. In this paper, we review existing indices of sediment connectivity and suggest potential avenues of development for meeting current basic and applied research needs. Specifically, we focus on terrestrial geomorphic systems dominated by processes that are driven by hydro-meteorological forcing, neglecting seismically triggered events, karstic systems and environments controlled by eolian processes. We begin by setting a conceptual framework that combines external forcings (drivers) and system (intrinsic) structural and functional properties relevant to sediment connectivity. This framework guides our review of response variables suitable for sediment connectivity indices. In particular, we consider three sample applications concerned with sediment connectivity in: (i) soil studies at the plot scale, (ii) bedload transport at the reach scale, and (iii) sediment budgets at the catchment scale. In relation to the set of response variables identified, we consider data availability and issues of data acquisition for use in indices of sediment connectivity. We classify currently available indices in raster based, object or network based, and indices based on effective catchment area. Virtually all existing indices address the degree of static, structural connectivity only, with limited attention for process-based, functional connectivity counterparts. Most recent developments in indices of sediment connectivity deal, to some extent, with different styles of anthropogenic and hydro-meteorological forcings and with the temporal variability of sediment con

Across the northern European Alps, a long tradition of Quaternary studies has constrained post-LGM (Last Glacial Maximum) landscape history. The same picture remains largely unknown for the southern portion of the orogen. In this work, starting from existing10Be exposure dating of three boulders in Val Viola, Central Italian Alps, we present the first detailed, post-LGM reconstruction of landscape (i.e., glacial, periglacial and paraglacial) response south of the Alpine divide. We pursue this task through Schmidt-hammer exposure-age dating (SHD) at 34 sites including moraines, rock glaciers, protalus ramparts, rock avalanche deposits and talus cones. In addition, based on the mapping of preserved moraines and on the numerical SHD ages, we reconstruct the glacier extent of four different stadials, including Egesen I (13.1 ± 1.1 ka), Egesen II (12.3 ± 0.6 ka), Kartell (11.0 ± 1.4 ka) and Kromer (9.7 ± 1.4 ka), whose chronologies agree with available counterparts from north of the Alpine divide. Results show that Equilibrium Line Altitude depressions (ΔELAs) associated to Younger Dryas and Early Holocene stadials are smaller than documented at most available sites in the northern Alps. These findings not only support the hypothesis of a dominant north westerly atmospheric circulation during the Younger Dryas, but also suggest that this pattern could have lasted until the Early Holocene. SHD ages on rock glaciers and protalus ramparts indicate that favourable conditions to periglacial landform development occurred during the Younger Dryas (12.7 ± 1.1 ka), on the valley slopes above the glacier, as well as in newly de-glaciated areas, during the Early Holocene (10.7 ± 1.3 and 8.8 ± 1.8 ka). The currently active rock glacier started to develop before 3.7 ± 0.8 ka and can be associated to the Löbben oscillation. Four of the five rock avalanches dated in Val Viola cluster within the Early Holocene, in correspondence of an atmospheric warming phase. By co

Conceptual models of first-order controls governing river channel dynamics in mountain streams have been rarely tested in the field. In this Ph.D. thesis we examine the effects of hydro-meteorological forcing and sediment supply on the bedload transport dynamics of mountain streams. To this purpose we select three step-pool mountain streams that share identical granitic lithology, but exhibit contrasting sediment supply and hydro-climatic conditions. The three study sites, which are located in Trentino, Eastern Italian Alps, include the Ussaia Creek (2.3 km2) in Val di Sole, and the Grigno and Tolvà Creeks (7 km2) in Valsugana. The former is characterized by high, sand-rich sediment supply delivered by some 20 m-thick glacigenic deposits. The latter two, which flow through glacially carved bedrock terrain, are disconnected from colluvial sediment inputs so that sediment sources are limited to channel banks and bars during high flows. Mean annual precipitation is respectively 844 mm in Ussaia Creek and 1511 mm in Grigno and Tolvà Creeks. All study streams experience, to variable extents, snowmelt and rainfall-induced bedload transporting flows. To estimate quantitatively the effects and the interactions associated with sediment supply and hydro-meteorological forcing, we monitor precipitation and atmospheric temperature. Hydrological levels at instrumented sections are recorded via pressure transducers. Bedload transport is monitored by tagging and tracking 632 stones (b-axis: 30 to 131 mm; weight 88-4004 g). The tracking of these PIT-tagged tracers was conducted from December 2013 to December 2015 by means of an RFID portable pole antenna. Cumulatively, a total of 16, 11 and 19 bedload events were monitored respectively at Grigno, Tolvà and Ussaia Creek. We measured displacement lengths occurred during inter-survey periods, induced by peak flows associated to snowmelt, rainfall or a combination of the two (mixed-type). Active channel depth was evaluated via direct d

Conceptual models of first-order controls governing river channel dynamics in mountain streams have been rarely tested in the field. In this Ph.D. thesis we examine the effects of hydro-meteorological forcing and sediment supply on the bedload transport dynamics of mountain streams. To this purpose we select three step-pool mountain streams that share identical granitic lithology, but exhibit contrasting sediment supply and hydro-climatic conditions. The three study sites, which are located in Trentino, Eastern Italian Alps, include the Ussaia Creek (2.3 km2) in Val di Sole, and the Grigno and Tolvà Creeks (7 km2) in Valsugana. The former is characterized by high, sand-rich sediment supply delivered by some 20 m-thick glacigenic deposits. The latter two, which flow through glacially carved bedrock terrain, are disconnected from colluvial sediment inputs so that sediment sources are limited to channel banks and bars during high flows. Mean annual precipitation is respectively 844 mm in Ussaia Creek and 1511 mm in Grigno and Tolvà Creeks. All study streams experience, to variable extents, snowmelt and rainfall-induced bedload transporting flows. To estimate quantitatively the effects and the interactions associated with sediment supply and hydro-meteorological forcing, we monitor precipitation and atmospheric temperature. Hydrological levels at instrumented sections are recorded via pressure transducers. Bedload transport is monitored by tagging and tracking 632 stones (b-axis: 30 to 131 mm; weight 88-4004 g). The tracking of these PIT-tagged tracers was conducted from December 2013 to December 2015 by means of an RFID portable pole antenna. Cumulatively, a total of 16, 11 and 19 bedload events were monitored respectively at Grigno, Tolvà and Ussaia Creek. We measured displacement lengths occurred during inter-survey periods, induced by peak flows associated to snowmelt, rainfall or a combination of the two (mixed-type). Active channel depth was evaluated via direct d

Conceptual models of first-order controls governing river channel dynamics in mountain streams have been rarely tested in the field. In this Ph.D. thesis we examine the effects of hydro-meteorological forcing and sediment supply on the bedload transport dynamics of mountain streams. To this purpose we select three step-pool mountain streams that share identical granitic lithology, but exhibit contrasting sediment supply and hydro-climatic conditions. The three study sites, which are located in Trentino, Eastern Italian Alps, include the Ussaia Creek (2.3 km2) in Val di Sole, and the Grigno and Tolvà Creeks (7 km2) in Valsugana. The former is characterized by high, sand-rich sediment supply delivered by some 20 m-thick glacigenic deposits. The latter two, which flow through glacially carved bedrock terrain, are disconnected from colluvial sediment inputs so that sediment sources are limited to channel banks and bars during high flows. Mean annual precipitation is respectively 844 mm in Ussaia Creek and 1511 mm in Grigno and Tolvà Creeks. All study streams experience, to variable extents, snowmelt and rainfall-induced bedload transporting flows. To estimate quantitatively the effects and the interactions associated with sediment supply and hydro-meteorological forcing, we monitor precipitation and atmospheric temperature. Hydrological levels at instrumented sections are recorded via pressure transducers. Bedload transport is monitored by tagging and tracking 632 stones (b-axis: 30 to 131 mm; weight 88-4004 g). The tracking of these PIT-tagged tracers was conducted from December 2013 to December 2015 by means of an RFID portable pole antenna. Cumulatively, a total of 16, 11 and 19 bedload events were monitored respectively at Grigno, Tolvà and Ussaia Creek. We measured displacement lengths occurred during inter-survey periods, induced by peak flows associated to snowmelt, rainfall or a combination of the two (mixed-type). Active channel depth was evaluated via direct d

Conceptual models of first-order controls governing river channel dynamics in mountain streams have been rarely tested in the field. In this Ph.D. thesis we examine the effects of hydro-meteorological forcing and sediment supply on the bedload transport dynamics of mountain streams. To this purpose we select three step-pool mountain streams that share identical granitic lithology, but exhibit contrasting sediment supply and hydro-climatic conditions. The three study sites, which are located in Trentino, Eastern Italian Alps, include the Ussaia Creek (2.3 km2) in Val di Sole, and the Grigno and Tolvà Creeks (7 km2) in Valsugana. The former is characterized by high, sand-rich sediment supply delivered by some 20 m-thick glacigenic deposits. The latter two, which flow through glacially carved bedrock terrain, are disconnected from colluvial sediment inputs so that sediment sources are limited to channel banks and bars during high flows. Mean annual precipitation is respectively 844 mm in Ussaia Creek and 1511 mm in Grigno and Tolvà Creeks. All study streams experience, to variable extents, snowmelt and rainfall-induced bedload transporting flows. To estimate quantitatively the effects and the interactions associated with sediment supply and hydro-meteorological forcing, we monitor precipitation and atmospheric temperature. Hydrological levels at instrumented sections are recorded via pressure transducers. Bedload transport is monitored by tagging and tracking 632 stones (b-axis: 30 to 131 mm; weight 88-4004 g). The tracking of these PIT-tagged tracers was conducted from December 2013 to December 2015 by means of an RFID portable pole antenna. Cumulatively, a total of 16, 11 and 19 bedload events were monitored respectively at Grigno, Tolvà and Ussaia Creek. We measured displacement lengths occurred during inter-survey periods, induced by peak flows associated to snowmelt, rainfall or a combination of the two (mixed-type). Active channel depth was evaluated via direct d

We monitor bedload transport and water discharge at six stations in two forested headwater streams of the Columbia Mountains, Canada. The nested monitoring network is designed to examine the effects of channel bed texture, and the influence of alluvial (i.e.step pools and riffle pools) and semialluvial morphologies (i.e.boulder cascades and forced step pools) on bedload entrainment and transport. Results indicate that dynamics of bedload entrainment are influenced by differences in flow resistance attributable to morphology. Scaled fractional analysis shows that in reaches with high form resistance most bedload transport occurs in partial mobility fashion relative to the available bed material, while calibers finer than 16mm attain full mobility during bankfull flows. Equal mobility transport for a wider range of grain sizes is achieved in reaches exhibiting reduced form resistance. Our findings confirm that the Shields value for mobilization of the median surface grain size depends on channel gradient and relative submergence; however, we also find that these relations vary considerably for cobble and gravel bed channels due to proportionality between dimensionless shear stress and grain size. Exponents of bedload rating curves across sites correlate most with the D90s of the mobile bed, however, where grain effects are controlled (i.e.along individual streams), differences in form resistance across morphologies exert a primary control on bedload transport dynamics. Application of empirical formulae developed for use in steep alpine channels present variable success in predicting transport rates in forested snowmelt streams. Formulae that explicitly account for reductions in mobile bed area and high morphological resistance associated with woody debris provide the best approximation to observed empirical data.

The variability of glacier response to atmospheric temperature rise in different topo-climatic settings is still a matter of debate. To address this question in the Central Italian Alps, we compile a post-LIA (Little Ice Age) multitemporal glacier inventory (1860-1954-1990-2003-2007) along a latitudinal transect that originates north of the continental divide in the Livigno Mountains and extends south through the Disgrazia and Orobie ranges, encompassing continental-to-maritime climatic settings. In these sub-regions, we examine the area change of 111 glaciers. Overall, the total glacierized area has declined from 34.1 to 10.1 km2, with a substantial increase in the number of small glaciers due to fragmentation. The average annual decrease (AAD) in glacier area has risen by about 1 order of magnitude from 1860-1990 (Livigno: 0.45; Orobie: 0.42; and Disgrazia: 0.39%a-1) to 1990-2007 (Livigno: 3.08; Orobie: 2.44; and Disgrazia: 2.27%a-1). This ranking changes when considering glaciers smaller than 0.5 km2 only (i.e., we remove the confounding caused by large glaciers in Disgrazia), so that post-1990 AAD follows the latitudinal gradient and Orobie glaciers stand out (Livigno: 4.07; Disgrazia: 3.57; and Orobie: 2.47%a-1). More recent (2007-2013) field-based mass balances in three selected small glaciers confirm post-1990 trends showing the consistently highest retreat in continental Livigno and minimal area loss in maritime Orobie, with Disgrazia displaying transitional behavior. We argue that the recent resilience of glaciers in Orobie is a consequence of their decoupling from synoptic atmospheric temperature trends, a decoupling that arises from the combination of local topographic configuration (i.e., deep, northfacing cirques) and high winter precipitation, which ensures high snow-avalanche supply, as well as high summer shading and sheltering. Our hypothesis is further supported by the lack of correlations between glacier change and glacier attributes in Orobie, as

The variability of glacier response to atmospheric temperature rise in different topo-climatic settings is still a matter of debate. To address this question in the Central Italian Alps, we compile a post-LIA (Little Ice Age) multitemporal glacier inventory (1860-1954-1990-2003-2007) along a latitudinal transect that originates north of the continental divide in the Livigno Mountains and extends south through the Disgrazia and Orobie ranges, encompassing continental-to-maritime climatic settings. In these sub-regions, we examine the area change of 111 glaciers. Overall, the total glacierized area has declined from 34.1 to 10.1 km2, with a substantial increase in the number of small glaciers due to fragmentation. The average annual decrease (AAD) in glacier area has risen by about 1 order of magnitude from 1860-1990 (Livigno: 0.45; Orobie: 0.42; and Disgrazia: 0.39%a-1) to 1990-2007 (Livigno: 3.08; Orobie: 2.44; and Disgrazia: 2.27%a-1). This ranking changes when considering glaciers smaller than 0.5 km2 only (i.e., we remove the confounding caused by large glaciers in Disgrazia), so that post-1990 AAD follows the latitudinal gradient and Orobie glaciers stand out (Livigno: 4.07; Disgrazia: 3.57; and Orobie: 2.47%a-1). More recent (2007-2013) field-based mass balances in three selected small glaciers confirm post-1990 trends showing the consistently highest retreat in continental Livigno and minimal area loss in maritime Orobie, with Disgrazia displaying transitional behavior. We argue that the recent resilience of glaciers in Orobie is a consequence of their decoupling from synoptic atmospheric temperature trends, a decoupling that arises from the combination of local topographic configuration (i.e., deep, northfacing cirques) and high winter precipitation, which ensures high snow-avalanche supply, as well as high summer shading and sheltering. Our hypothesis is further supported by the lack of correlations between glacier change and glacier attributes in Orobie, as

Debris-flow monitoring in instrumented areas is an invaluable way to gather field data that may improve the understanding of these hazardous phenomena. A new experimental site has been equipped in the Autonomous Province of Bozen-Bolzano (Eastern Alps, Italy) for both monitoring purposes and testing early warning systems. The study site (Gadria basin) is a 6.3 km2 catchment subjected to frequent debris flows. The monitoring system in the Gadria basin consists of rain gauges, radar sensors, geophones, video cameras, piezometers and soil moisture probes. Transmission of data and alerts from the instruments exploits in part radio technology. The paper presents the data gathered during the first three years of activity, with two debris-flow events recorded at the station varying in magnitude and characteristics, and discusses the perspectives of debris-flow monitoring and related research. © 2014 Springer Science+Business Media Dordrecht.

In this paper we quantify the sediment dynamics in the formerly glaciated Zielbach catchment in the Italian Alps from the end of the Last Glacial Maximum (LGM) until today. As a basis for our quantification, we use the stratigraphic record offered by a 3.5 km2 large fan that we explore with a seismic survey, stratigraphic analyses of drillhole material, and 14C ages measured on organic matter encountered in these drillings. In addition, we calculate past denudation rate variability in the fan deposits using concentrations of cosmogenic 10Be. We merge this information into a scenario of how the sediment flux has changed through time and how this variability can be related to climatic variations, framed within well-known paraglacial models. The results document a highly complex natural system. From the LGM to the very early Holocene, ice-melted discharge and climate variability promoted a high sediment flux (sedimentation rate up to 40 mm/yr). This flux then dramatically decreased toward interglacial values (0.8 mm/yr at 5-4 calibrated kyr B.P.). However, in contrast to the trend of classic paraglacial models, the flux recorded at Zielbach shows secondary peaks at 6.5 ka and 2.5 ka, with values of 13 mm/yr and 1.5 mm/yr, respectively. Paleo-denudation rates also decrease from ̃33 mm/yr at the beginning of the Holo cene to 0.42 mm/yr at 5 ka, with peaks of ̃6 mm/yr and 1.1 mm/yr at 6.5 ka and 2.5 ka. High-amplitude climate change is the most likely cause of the secondary peaks, but anthro pogenic activities may have contributed as well. The good correlation between paleo-sedimentation and paleo-denudation rates suggests that the majority of the deglaciated material destocked from the Zielbach catchment is stored in the alluvial fan. © 2014 Geological Society of America.

This study examines channel-reach morphology and bedload yield dynamics in relation to landscape structure and snowmelt hydrology in headwater streams of the Columbia Mountains, Canada. Data collection relies on field surveys and geographic information systems analysis in conjunction with a nested monitoring network of water discharge and bedload transfer. The landscape is characterized by subdued, formerlyglaciated upland topography in which the geomorphic significance of landslides and debris flows is negligible and fluvial processes prevail. While the spatial organization of channel morphology is chiefly controlled by glacially imposed local slope in conjunction with wood abundance and availability of glacigenic deposits, downstream patterns of the coarse grain-size fraction, bankfull width, bankfull depth, and stream power are all insensitive to systematic changes of local slope along the typically stepped long profiles. This is an indication that these alluvial systems have adjusted to the contemporary snowmelt-driven water and sediment transport regimes, and as such are able to compensate for the glacially-imposed boundary conditions. Bedload specific yield increases with drainage area suggesting that fluvial re-mobilization of glacial and paraglacial deposits dominate the sedimentary dynamics of basins as small as 2 km2. Stepwise multiple regression analysis shows that annual rates of sediment transfer aremainly controlled by the number of peak events over threshold discharge. During such events, repeated destabilization of channel bed armoring and re-mobilization of sediment temporarily stored behind LWD structures can generate bedload transport across the entire snowmelt season. In particular, channel morphology controls the variability of bedload response to hydrologic forcing. In the present case studies, we show that the observed spatial variability in annual bedload yield appears to be modulated by inter-basin differences in morphometric characteristics

This study aims to investigate the cryosphere of the Lombardy region (Central Italian Alps) by compiling and analysing glacier, rock glacier, and protalus rampart inventories. To this purpose, I have employed remote sensing techniques and in-situ measurements for delineating the contemporary and historical extent of glaciers and contemporary extent of rock glaciers and protalus ramparts. In order to better identify and highlight the response of the regional cryosphere to climate change, the LIA maximum extent has been reconstructed for nine selected glaciers and their fluctuations since then have been discussed and analyzed in relation to temperature and precipitation recorded at ground weather stations. The main objectives of this doctoral dissertation are to: compile glacier, rock glacier and protalus rampart regional inventory for the Central Italian Alps (Lombardy region) exploitable for investigations about permafrost distribution; elucidate the linkages between the occurrence of periglacial landforms (rock glaciers and protalus ramparts) and local litho-topographic attributes; examine the variability of periglacial activity in relation to terrain elevation and mean annual precipitation; gain new insights about the impact of the Pleistocene-Holocene climatic transition on the periglacial domain within the study area; examine the linkages between glaciers location, glaciers attributes (e.g., size, aspect, ELA0) and mean annual precipitation; analyze the relations between glaciers location, size, aspect, ELA0 and areal variations since 1991; analyze post-LIA (1860) glacier fluctuations for nine selected glaciers from different sub-regions of the central Italian Alps; investigate glacier sensitivity to climate change (i.e., precipitation and temperature).

This study examines channel-reach morphology and bedload yield dynamics in relation to landscape structure and snowmelt hydrology in headwater streams of the Columbia Mountains, Canada. Data collection relies on field surveys and geographic information systems analysis in conjunction with a nested monitoring network of water discharge and bedload transfer. The landscape is characterized by subdued, formerlyglaciated upland topography in which the geomorphic significance of landslides and debris flows is negligible and fluvial processes prevail. While the spatial organization of channel morphology is chiefly controlled by glacially imposed local slope in conjunction with wood abundance and availability of glacigenic deposits, downstream patterns of the coarse grain-size fraction, bankfull width, bankfull depth, and stream power are all insensitive to systematic changes of local slope along the typically stepped long profiles. This is an indication that these alluvial systems have adjusted to the contemporary snowmelt-driven water and sediment transport regimes, and as such are able to compensate for the glacially-imposed boundary conditions. Bedload specific yield increases with drainage area suggesting that fluvial re-mobilization of glacial and paraglacial deposits dominate the sedimentary dynamics of basins as small as 2 km2. Stepwise multiple regression analysis shows that annual rates of sediment transfer aremainly controlled by the number of peak events over threshold discharge. During such events, repeated destabilization of channel bed armoring and re-mobilization of sediment temporarily stored behind LWD structures can generate bedload transport across the entire snowmelt season. In particular, channel morphology controls the variability of bedload response to hydrologic forcing. In the present case studies, we show that the observed spatial variability in annual bedload yield appears to be modulated by inter-basin differences in morphometric characteristics

Basin-wide erosion rates can be determined through the analysis of in situ-produced cosmogenic nuclides. In transient landscapes, and particularly in mountain catchments, erosion and transport processes are often highly variable and consequently the calculated erosion rates can be biased. This can be due to sediment pulses and poor mixing of sediment in the stream channels. The mixing of alluvial sediment is one of the principle conditions that need to be verified in order to have reliable results. In this paper we perform a field-based test of the extent of sediment mixing for a w42 km2 catchment in the Alps using concentrations of river-born 10Be. We use this technique to assess the mechanisms and the spatiotemporal scales for the mixing of sediment derived from hillslopes and tributary channels. The results show that sediment provenance and transport, and mixing processes have a substantial impact on the 10Be concentrations downstream of the confluence between streams and tributary channels. We also illustrate that the extent of mixing significantly depends on: the sizes of the catchments involved, the magnitude of the sediment delivery processes, the downstream distance of a sample site after a confluence, and the time since the event occurred. In particular, continuous soil creep and shallow landsliding supply high 10Be concentration material from the hillslope, congruently increasing the 10Be concentrations in the alluvial sediment. Contrariwise, a high frequency of mass-wasting processes or the occurrence of sporadic but large-magnitude events results in the supply of low-concentration sediment that lowers the cosmogenic nuclide concentration in the channels. The predominance of mass-wasting processes in a catchment can cause a strong bias in detrital cosmogenic nuclide concentrations, and therefore calculated erosion rates may be significantly over- or underestimated. Accordingly, it is important to sample as close as possible to the return-period of large-s

Wepresent a regional inventory of rock glaciers (n=1514) and protalus ramparts (228) for the Lombardy region, central Italian Alps. To identify and classify the landformswe inspect three sequential air-orthophoto mosaics and a 2 m-DSM, and conduct confirmatory field work. The inventory forms an empirical basis to analyze: (i) the relative contribution of hillslope (i.e., talus slopes) and glacial (i.e., moraines) sediment stores to rock glacier sediment supply; (ii) linkages between the landforms inventoried and local topographic attributes; (iii) the spatial variability of periglacial activity in relation to a parsimonious set of environmental variables (i.e., elevation, precipitation, and lithology); and (iv) the effects of the Pleistocene–Holocene climatic transition on the distribution of intact and relict landforms. This analysis reveals that the elevation of rock glacier termini can vary over 200 m as a function of slope aspect. In turn, the distribution of rock glaciers among aspect categories is controlled by the structure of the valley network that promotes NWand SE exposures. Talus rock glaciers prevail numerically over the glacier-related typology, even though the latter population appears to have increased during the Holocene. Relict and intact rock glaciers have distinct spatial patterns in that the former display, on average, a 400-melevation drop and a less clustered distribution towards northern aspects, suggesting that they have developed in more “permafrost-prone” climatic conditions. Analyzing the study region through a 27.5 km-grid has been instrumental for showing that the rock glacier specific area and terminus elevation are: (i) positively correlatedwith terrain elevation; and (ii) negatively correlated with mean annual precipitation. As a consequence, in relation to Holocene generalized atmospheric temperature rise, intact rock glaciers have progressively disappeared fromthewetter and milder portions of the central Italian Alps. Analysis of r

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.

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

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.

Debris flow is an efficient process of sediment transfer from slope base to piedmont depositional fans in mountain drainage basins. To advance understanding of debris-flow sediment dynamics at the regional scale, we analyze a historical (1998-2009) database of debris flows from 77 basins of Alto Adige Province, northeastern Italy. By combining information on event volumetric deposition, high-resolution digital topography, and Quaternary sediment mapping we are able to link debris-flow sediment flux to morphometry, lithologic variability, and sediment availability. We show that basin-wide specific sediment yield (SSY) scales as an inverse power function of basin area. This function is strongly controlled by the way rock type and abundance of Quaternary deposits affect the rate of downstream sediment recruitment. When sediment flux associated with each debris-flow event is subsumed across discrete spatial increments of the entire region, a complex sedimentary signature in the area-SSY space is apparent. That is, SSY increases downstream up to areas as large as 1 km2, and starts to decline beyond this scale, regardless of sediment availability. We propose that this area-SSY relation is characteristic of debris flow-dominated settings.

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.

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

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.

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 th

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 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.

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 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.

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 thi

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 redist

Colluvial sediment dynamics are examined using a 70-year landslide inventory in formerly glaciated mountain drainage basins of coastal British Columbia, Canada. Landslide sediment transfer is documented by identifying landslide types, and by characterizing preferential sites of landslide initiation, delivery, and storage across spatial scales. Data analysis reveals that open-slope landslides delivering material to seasonal or perennial channels and fluvial terraces are the dominant mechanisms of sediment transfer. This finding suggests high instability of the low-order channel network and its ongoing re-organization (degradation) after generalized sediment recharge occurred in the last glacial maximum. In the study period, landslide activity across the landscape has generated net degradation on planar slopes and first-order colluvial channels, whereas unchannelled valleys, higher-order colluvial channels and alluvial channels have accumulated material. The scaling relation of the landslide sediment yield appears to be controlled by the spatial arrangement of the relict glacial macro-forms. Landslide yield is highest in unchannelled topography, decreases at the scale of channel initiation (Ad~0.002 km2), and remains constant for drainage areas where length scales of cirque/valley walls and hanging valley floors overlap (0.002bAdb0.06). Injections of landslide material start declining consistently beyond areas larger than 0.6 km2 (the scale of relict glacial trough initiation), where fluvial environments become increasingly disconnected from landslide inputs. Cumulative yield indicates that colluvial sediment redistribution is limited to small basins; specifically, 90% of the colluvial load is released at scales smaller than about 0.6 km2

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.

We examine the spatial distribution of channel-reach morphologies in formerly glaciated mountain drainage basins of coastal British Columbia, Canada. Using field- and geographic information systems-derived data, we show that the local channel slope and the degree of colluvial-alluvial coupling imposed by the glacial valley morphology dictate the spatial organization of channel types. In particular, the complex, glacially induced channel long profile produces characteristic sequences of channel reaches that depart from the downstream succession (colluvial/boulder-cascade/step-pool/rapids/riffle-pool) distinctive of simple unglaciated mountain streams. Typically, 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. We document that channel types are well separated in plots of slope versus shear stress, area versus shear stress, and slope versus relative roughness. In agreement with these outcomes, multivariate discriminant analyses coupled with principal component analysis of 98 study reaches yield a highly successful channel-type classification when slope, shear stress, and relative roughness are considered. Success rates, depending on whether or not boulder-cascade reaches are pooled together with step-pools, are 88% and 75%, respectively. Previous work in unglaciated settings has suggested that mountain channels have distinct bed morphology states that vary primarily with slope; our study reveals that even in formerly glaciated valleys, where slope is largely inherited from glacial times, these distinct bed states exist and vary (mostly) with slope, adding considerable strength to this empirical knowledge

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 d

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.

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 glaciated landscapes is examined by analyzing the structure of geomorphic process domains and channel long profiles. To identify process domains we use channel surveys and GIS analysis to construct slope-area transects of the channel network. This 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 (contributing area <1 km2), 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. Slope-area relations typical of unglaciated equilibrium environments do not apply here. 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 subdomain is proposed. Comparison between field- and GIS-measured slopes reveals that GIS-associated error is not uniform between process domains, and that GIS-based plots do not successfully discriminate field-based process domains. 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.

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 low

In glaciated regions of 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. Currently, fluvial and hillslope processes dominate the landscape, and are slowly reshaping the glacial inherited anisotropy. The aim of our study is to examine the evolution of glaciated mountainous landscapes by analysing the structure of geomorphic process domains, channel long-profiles, downstream trends of hydraulic geometry and channel morphology. The methodological approach entailed extensive channel surveys and GIS analysis to plot area-slope transects along the main stem of drainage basins. This analysis reveals generalized process-form disequilibrium with a mismatch between topographic signatures and currently active geomorphic process domains. In debris-flow dominated 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 6*10-2 km2 and produce channel long-profiles similar to those observed for rivers responding to tectonic forcing. The well-established area-slope relations with simple downstream power law relations for unglaciated environments do not apply here, although the concept of process domains appears to hold. In other words, the spatial distribution of process domains on an area-slope plot may be similar but where the topography plots on these process domains varies between landscape types. At the reach scale, these same glaciated basins display significant deviations from simple downstream variation of channel slope, width, stream power and consequently the sequencing of channel morphology. Such variations are due to local, glacially-induced influences that typically reset downstream trends

River networks define specific scaling relations in the landscape. Accordingly, contributing area scales with local slope gradient controlling geomorphic process domains hence rates of erosion; and channel-reach hydraulic geometry and morphology. In currently glaciated environments ice flows possess peculiar geomorphic erosion and transport laws which likely disturb pre-glacial landscape structure and superimpose "glacial" scaling dependences. On such premise, it is hypothesized that formerly glaciated environments currently exhibit transient scaling dependences that deviate significantly from those documented in unglaciated analogs. Study sites are drawn from the Coast Mountains of British Columbia. Results show direct spatial scale linkages and generalized departure from unglaciated scaling relations at all levels. Glacial macro-forms, by imposing local channel gradient and degree of colluvial-alluvial coupling, affect the spatial distribution of process domains, which in turn control channel-reach morphology and hydraulic geometry. In particular, morphometric characteristics of relict glacial troughs introduce a peculiar colluvial-alluvial transition trend in the area-slope space. Hanging valleys, which enclose purely alluvial riffle-pool reaches separate strongly-coupled colluvial reaches located both up- and down-stream. Transitions across process domains tend to reset downstream trends of channel width, depth, and D95. Exponents of area-width and area-depth relations deviate significantly from 0.5 and 0.33. Specifically, colluvial channels exhibit higher downstream channel widening, while fluvial reaches denote negative (downstream narrowing) or nearly null exponents. To model channel width, a Manning-based expression, which expresses roughness as a function of D95, is applied. Complex channel-width trends that were measured in the field are described reasonably well. Channel width in colluvial reaches is consistently underestimated. The stepped topography of

This paper reviews sediment transport and channel morphology in small, forested streams in the Pacific Northwest region of North America to assess current knowledge of channel stability and morphology relevant to riparian management practices around small streams. Small channels are defined as ones in which morphology and hydraulics may be significantly influenced by individual clasts or wood materials in the channel. Such channels are headwater channels in close proximity to sediment sources, so they reflect a mix of hillslope and channel processes. Sediment inputs are derived directly from adjacent hillslopes and from the channel banks. Morphologically significant sediments move mainly as bed load, mainly at low intensity, and there is no standard method for measurement. The larger clastic and woody elements in the channel form persistent structures that trap significant volumes of sediment, reducing sediment transport in the short term and substantially increasing channel stability. The presence of such structures makes modeling of sediment flux in these channels - a potential substitute for measurement - difficult. Channel morphology is discussed, with some emphasis on wood related features. The problem of classifying small channels is reviewed, and it is recognized that useful classifications are purpose oriented. Reach scale and channel unit scale morphologies are categorized. A "disturbance cascade" is introduced to focus attention on sediment transfers through the slope channel system and to identify management practices that affect sediment dynamics and consequent channel morphology. Gaps in knowledge, errors, and uncertainties have been identified for future research. JAWRA Copyright © 2005.

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.

We use magnitude-frequency analysis as a statistical tool to quantify the erosion caused by landslides and debris flows. Using air-photo- and ground-derived data we show that the departure from power-law distribution customarily observed for small magnitude is an artefact of sampling deficiencies. Nonetheless, the total distribution is not sensitive to the frequency of small slides and total erosion remains adequately represented in the air-photo-derived data. Our data also demonstrate a real departure from simple scaling at much larger magnitudes, the cause of which is not definitively established. © 2004 John Wiley and Sons, Ltd.

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.

Landslide inventories are routinely compiled by means of aerial photo interpretation (API). When examining photo pairs, the forest canopy (notably in old-growth forest) hides a population of "not visible" landslides. In the present study, we attempt to estimate how important is the contribution of landslides not detectable from aerial photographs to the global mass of sediment production from mass failures on forested terrain of the Capilano basin, coastal British Columbia. API was coupled with intensive fieldwork for identification and measurement of all landslides. A 30-year framework was adopted. We show that "not visible" landslides can represent up to 85% of the total number of failures and account for 30% of the volume of debris mobilised. Such percentages display high sub-basin variability with rates of sediment production varying by one order of magnitude between two sub-basins of the study area. This is explained qualitatively by GIS-based analysis of slope frequency distributions, drainage density, and spatial distribution of surficial materials. Such observations find further support in the definitions of transport-limited and supply-limited basins. As a practical consideration to land managers, we envisage that supplementary fieldwork for landslide identification is mandatory in transport-limited systems only. Fieldwork has demonstrated that gully-related failures have a greater importance than one could expect from API. © 2002 Elsevier Science B.V. All rights reserved.

The impacts of logging activities on mass wasting were examined in five watersheds in the coastal mountains of British Columbia. Historical aerial photos were used to document mass wasting events, and their occurrence was related to logging activities in the study basins. Logged and forested areas were compared in terms of mass wasting magnitude and frequency, with reference to site characteristics. The recovery time of the landscape after logging was assessed. Bedrock type and basin physiography had no identifiable effect on mass wasting frequency and magnitude. Mass wasting failure was primarily controlled by slope gradient. Basin vulnerability increased, following clearcutting relative to forested areas, in that mass wasting was initiated on gentler slopes. The volume of sediment produced from logged slopes is of the same order as that from forested areas, which are steeper by as much as 10°. In both logged and forested areas, the size distribution of mass wasting events follows an exponential distribution. However, the variability in mass wasting size in forested areas is much higher than that obtained for logged areas. The recovery time after forest harvesting is over 20 years, which confirms published estimates based on vegetation reestablishment. Continuous disturbance of the basin, however, may extend the recovery time for the whole basin well beyond 20 years. © 2002 Elsevier Sciece B.V. All rights reserved.