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Schematic of recommended methods and sampling frequencies to characterize the main sediment balance components of the fluvial sedimentation prism shown in Figure 1. Component 1 includes valley, floodplain and slope sediment sources/storage, Component 2, fluvial transport and Component 3 transfer to lacustrine sinks. The gradient bars indicate a qualitative assessment of the effect of sampling frequency on the quality of flux data derived from the recommended methods from less ideal (white) to ideal (black)
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Fluvial processes dominate sediment flux from most cold environments and as such are particularly sensitive to environmental change. However, these systems demonstrate high variability in flow and sediment transfer rates in both the short and long-term which presents specific problems for establishing integrated sediment flux studies. The objective...
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... comparability can be achieved by 1) consistency in methods for monitoring sediment flux, and 2) appropriate sampling frequencies. Figure 8 shows the three main sediment balance components of the fluvial sedimentation prism and a suggested framework for the most appropriate methods for integrating the measurement of sediment flux. The framework is presented as the 'ideal' approach to characterizing fluxes but in some cases application of some or all of these methods will not be possible. ...
Citations
... Despite evidence for complex and accelerated Arctic change, monitoring of Arctic rivers declined significantly in the late 20th century (Guymon, 1974;Lewis & Lamoureux, 2010;Syvitski et al., 2000), and there are relatively few studies and limited temporal data for estimating Arctic sediment yields compared to other environments (Orwin et al., 2010). Furthermore, most sediment yields are estimated using fluvial rating curve methods, limiting their time series to the length of monitoring, which in only a couple Arctic studies, to our knowledge, spanned more than a decade (Beel et al., 2018;Bogen & Bønsnes, 2003). ...
Lake‐based studies can provide seasonal‐ to millennial‐scale records of sediment yield to improve our understanding of catchment‐scale sediment transfer and complement shorter fluvial‐based sediment transport studies. In this study, sediment accumulation rates at 40 coring locations in Lake Peters, Brooks Range, Alaska, over ca. 42 years, calculated using fallout radionuclides and sediment density patterns, were spatially modelled based on distance from the primary inflow and lake water depth. We estimated mean interdecadal specific sediment yield (Mg km ⁻² year ⁻¹ ) using the spatially modelled sediment accumulation rates and compared that result to fluvial‐based sediment delivery for 2015–2016 open‐channel seasons, as well as to yields reported for other Arctic catchments. Using the lake‐based method, mean yield to Lake Peters between ca. 1973 and 2015 was 52 ± 12 Mg km ⁻² year ⁻¹ , which is comparable with fluvial‐based modelling results of 33 (20–60) Mg km ⁻² year ⁻¹ in 2015 and 79 (50–140) Mg km ⁻² year ⁻¹ in 2016 (95% confidence intervals), respectively. Although 2016 was a year of above average sedimentation, the last extreme depositional event probably occurred between ca. 1970 and 1976 when a basal layer of fine sand was deposited in a broadly distributed, relatively thick and coarse bed, which we used for lake‐wide correlation. The dual lacustrine–fluvial method approach permits study of within‐lake and catchment‐scale processes. Within Lake Peters, sedimentation patterns show decreasing fluxes down‐lake, sediment bypassing near the primary inflow, the influence of secondary inflows and littoral redistribution, and a focusing effect in the deep proximal basin. At the watershed scale, sediment yield is largely driven by intense summer rainfall and strong seasonal hydroclimatic variability. This research informs paleo‐environmental reconstruction and environmental system modelling in Arctic lake catchments.
... The rate of these changes is usually assessed by estimating the sediment yields and the relationship between the river transport components [3,4]. Regional and local conditions determine the high variability of total sediment yields from glaciated (600~40,000 t/y) and unglaciated (500-1000 t/y) catchments of the polar regions [5]. The main determining factors include the rate of glacier and snow cover ablation and the frequency of different genesis floods [6][7][8]. ...
... The main determining factors include the rate of glacier and snow cover ablation and the frequency of different genesis floods [6][7][8]. For high Arctic proglacial rivers, the dominance of suspended sediment transport is characteristic, constituting up to 80% of sediment yields (while the bedload is up to 37%) [5,9]. The local character and episodic nature of the coarse sediments delivery to the channels of Arctic rivers makes the bedload discharge show higher temporal and spatial variability than the suspended load Water 2023, 15, 1368 2 of 20 discharge [5,10]. ...
... For high Arctic proglacial rivers, the dominance of suspended sediment transport is characteristic, constituting up to 80% of sediment yields (while the bedload is up to 37%) [5,9]. The local character and episodic nature of the coarse sediments delivery to the channels of Arctic rivers makes the bedload discharge show higher temporal and spatial variability than the suspended load Water 2023, 15, 1368 2 of 20 discharge [5,10]. The rate of bedload and its relationship to other components of fluvial transport (suspended and dissolved loads) determine changes in valley floor and channel morphology [11,12]. ...
A four-day glacier-melt flood (13–16 August 2013) caused abrupt geomorphic changes in the proglacial gravel-bed Scott River, which drains the small (10 km2) Scott Glacier catchment (SW Svalbard). This type of flood occurs on Svalbard increasingly during periods of abnormally warm or rainy weather in summer or early autumn, and the probability of occurrence grows in direct proportion to the increase in temperature and/or precipitation intensity. In the summer of 2013, during the measurement season, the highest daily precipitation (17 mm) occurred on 13 August. During the following four days, it constituted in total 47 mm, i.e., 50% of the precipitation total for the measurement period of 2013. The largest flood in 20 years was caused by high precipitation with a synchronous rise in temperature from about 1.0 to 8.6 °C. These values exceeded multi-year averages (32 mm and 5.0 °C, respectively) at an average discharge of 0.9 m3/s (melt season mean 1986–2011). These conditions caused a rapid and abrupt response of the river with the dominant (90%) glacier-fed. The increase in discharge to 4.6 m3/s, initiated by the glacial flood, mobilized significant amounts of sediment in the river bed and channel. Geomorphic changes within the alluvial fan as an area of 58,940 m2, located at the mouth of the Scott River, were detected by multi-sites terrestrial laser scanning using a Leica Scan Station C10 and then estimated using Geomorphic Change Detection (GCD) software. The changes found involved 39% of the alluvial fan area (23,231 m2). The flood-induced total area of lowering (erosion) covered 26% of the alluvial fan (6035 m2), resulting in the removal of 1183 ± 121 m3 of sediment volume. During the final phase of the flood, two times more sediment (1919 ± 344 m3) was re-deposited within the alluvial fan surface, causing significant aggradation on 74% of its area (17,196 m2). These geomorphic changes resulted in an average lowering (erosion) of the alluvial fan surface of 0.2 m and an average rising (deposition) of 0.1 m.
... Furthermore, studies on proglacial evolution increasingly apply the concept of connectivity to assess how hydrological and sedimentrelated changes induced by glacier retreat and permafrost degradation will propagate within a catchment (Cavalli et al., 2019a and references therein). In such environments, sediment transfer is highly variable in both space and time (Orwin et al., 2010;Beylich and Laute, 2015;Carrivick and Heckmann, 2017;Cavalli et al., 2019a;Comiti et al., 2019) due to the number of transporting agents (i.e. ice, snow, gravity or water), to seasonally-varying runoff conditions, and to their complex and rapidly-evolving morphology. ...
In the past decade, sediment connectivity has become a widely recognized characteristic of a geomorphic system. However, the quantification of functional connectivity (i.e. connectivity which arises due to the actual occurrence of sediment transport processes) and its variation over space and time is still a challenge. In this context, this study assesses the effects of expected future phenomena in the context of climate change (i.e. glacier retreat, permafrost degradation or meteorological extreme events) on sediment transport dynamics in a glacierised Alpine basin. The study area is the Sulden river basin (drainage area 130 km²) in the Italian Alps, which is composed of two geomorphologically diverse sub-basins. Based on graph theory, we evaluated the spatio-temporal variations in functional connectivity in these two sub-basins. The graph-object, obtained by manually mapping sediment transport processes between landforms, was adapted to 6 different hydro-meteorological scenarios, which derive from combining base, heatwave and rainstorm conditions with snowmelt and glacier-melt periods. For each scenario and each sub-basin, the sediment transport network and related catchment characteristics were analysed. To compare the effects of the scenarios on functional connectivity, we introduced a connectivity degree, calculated based on the area of the landforms involved in sediment cascades. Results indicate that the area of the basin connected to its outlet in terms of sediment transport might feature a six-fold increase in case of rainstorm conditions compared to “average” meteorological conditions assumed for the base scenario. Furthermore, markedly different effects of climate change on sediment connectivity are expected between the two sub-catchments due to their contrasting morphological and lithological characteristics, in terms of relative importance of rainfall-triggered colluvial processes vs temperature-driven proglacial fluvial dynamics.
... In the (peri)glacial climate-morphological zone, mixed-type genetic landforms and clasts that are largely different regarding their granulometry, morphology and situmetry (clast orientation) are common due to the shortdistance movement of the ice "telescoped" into each other. Some are also found in the same site as pattern grounds which downslope grade from in situ heave-induced landforms into lobes of solifluction/gelifluction [85][86][87][88][89]. Their distinction is frequently only possible based on a meticulous investigation of the aforementioned sedimentological parameters such as sorting and roundness (see diagrams). ...
Abstract: In this study, six basic Quaternary landform series (LFS) and their sedimentary deposits (LFS1 aeolian, LFS 2.1 to 2.2 mass wasting, LFS 3 cryogenic-glacial, LFS 4.1 to 4.6 fluvial, LFS 5.1 to 5.2 coastal-marine, LFS 6.1 to 6.3 lacustrine) are subdivided into subtypes and examined with regard to their sedimentological parameters and their mineralogical and chemical compositions. Emphasis is placed on the textural (related to transport and deposition), compositional (sediment load/weight, Eh and pH) and geodynamic maturity of the sedimentary deposits which are influenced by the parent
lithology and bedrock tectonic and by the climate during the last 2 Ma. To constrain the development of the LFS and their sediments, composite trend-line diagrams are designed combining sedimentological (x-axis) and chemical/mineralogical dataset (y-axis): (1) sorting vs. heavy mineral content; (2) sphericity of grains vs. silica/carbonate contents; and (3) median vs. Ti/Fe ratios. In addition, the x-y plots showing the log SiO2/Al2O3 vs. log Na2O/K2O are amended by a dataset of the three most common clay minerals, i.e., kaolinite-, mica-, and smectite-group clay minerals. Such joint sedimentological-chemical mineralogical investigations focused on the depositional environment of unconsolidated clastic sediments of Quaternary age can be used to describe the economic geology
and environmental geology of mineral deposits in the pre-Quaternary sedimentary series according to the phrase: “The Present is the key to the Past”. Both trend diagrams and compositional x-y plots can contribute to constraining the development of the full transect of landform series from the fluvial incision and slope retreat to reef islands fringing the coastal zone towards the open sea as far as they are built up of clastic sedimentary deposits enriched in siliceous and/or carbonate minerals. Climate
zonation and crustal maturity are the exogenous and endogenous “drivers”, as can be deduced from the compositional (mineralogy and chemistry) and physical (transport and deposition) variations observed in the Quaternary sediments. The current study bridges the gap between a review only based on literature and a hybrid manual generated by practical field studies devoted to applied geosciences in economic and environmental geology (“E & E issue”).
... The effectiveness of these changes can be assessed by examining the component relationships of river transport [2][3][4][5]. In the polar regions, the total sediment yields from glaciated (600~40,000 t y −1 ) and non-glaciated (500-1000 + t y −1 ) catchments show great variability [6]. It is mainly determined by different ablation rates as well as the frequency of precipitation-driven high flows and floods [7], as well as outburst floods [8]. ...
... It is mainly determined by different ablation rates as well as the frequency of precipitation-driven high flows and floods [7], as well as outburst floods [8]. In particular, High Arctic proglacial rivers are dominated by sediment transport, where the contribution of bedload varies from <1% to 37% and is usually several times lower than the suspended load (from 2% to 81%) [6,9]. Bedload flux is characterized by greater temporal and spatial variability than suspended flux [6], in addition to the local character of sediment delivery to the channel (e.g., bank slumps) [10] and its dominance (70-90%) in the total sediment loads that are transported during flood events [6,11]. ...
... In particular, High Arctic proglacial rivers are dominated by sediment transport, where the contribution of bedload varies from <1% to 37% and is usually several times lower than the suspended load (from 2% to 81%) [6,9]. Bedload flux is characterized by greater temporal and spatial variability than suspended flux [6], in addition to the local character of sediment delivery to the channel (e.g., bank slumps) [10] and its dominance (70-90%) in the total sediment loads that are transported during flood events [6,11]. Bedload and its relation to other fluvial transport components (suspended and dissolved loads) is an important indicator for assessing the stage of a river system's development. ...
This study, which was conducted between 2010 and 2013, presents the results of direct, continuous measurements of the bedload transport rate at the mouth section of the Scott River catchment (NW part of Wedel-Jarlsberg Land, Svalbard). In four consecutive melt seasons, the bedload flux was analyzed at two cross-sections located in the lower reaches of the gravel-bed proglacial river. The transported bedload was measured using two sets of River Bedload Traps (RBTs). Over the course of 130 simultaneous measurement days, a total of 930 bedload samples were collected. During this period, the river discharged about 1.32 t of bedload through cross-section I (XS I), located at the foot of the alluvial fan, and 0.99 t through cross-section II (XS II), located at the river mouth running into the fjord. A comparison of the bedload flux showed a distinctive disproportion between cross-sections. Specifically, the average daily bedload flux QB was 130 kg day−1 (XS I) and 81 kg day−1 (XS II) at the individual cross-profiles. The lower bedload fluxes that were recorded at specified periods in XS II, which closed the catchment at the river mouth from the alluvial cone, indicated an active role of aggradation processes. Approximately 40% of all transported bedload was stored at the alluvial fan, mostly in the active channel zone. However, comparative Geomorphic Change Detection (GCD) analyses of the alluvial fan, which were performed over the period between August 2010 and August 2013, indicated a general lowering of the surface (erosion). It can be assumed that the melt season’s average flows in the active channel zone led to a greater deposition of bedload particles than what was discharged with high intensity during floods (especially the bankfull stage, effectively reshaping the whole surface of the alluvial fan). This study documents that the intensity of bedload flux was determined by the frequency of floods. Notably, the highest daily rates recorded in successive seasons accounted for 12–30% of the total bedload flux. Lastly, the multi-seasonal analysis showed a high spatio-temporal variability of the bedload transport rates, which resulted in changes not only in the channel but also on the entire surface of the alluvial fan morphology during floods.
... Quantitative estimates of annual fluvial suspended sediment yield (hereafter, "sediment yield") are sought by physical scientists as signals of environmental dynamics, by ecologists for their associations with water quality and habitat value, and by engineers for hydroinfrastructure and river system design. Measuring sediment yields presents a challenge, because sediment transfer is inherently variable in space and time (Morehead, Syvitski, Hutton, & Peckham, 2003;Orwin, Lamoureux, Warburton, & Beylich, 2010). Research from glaciated Arctic catchments indicates that sediment transfer typically reflects catchment-scale processes (Hodgkins, Cooper, Wadham, & Tranter, 2003), including meteorological forcing (Lewis & Lamoureux, 2010;Syvitski, 2002), glacial dynamics (Bogen & Bønsnes, 2003;Gurnell, Hannah, & Lawler, 1996;Hodson & Ferguson, 1999;Hodson, Tranter, Dowdeswell, Gurnell, & Hagen, 1997), and other geomorphological processes (Hasholt, 2016;Hasholt et al., 2006). ...
... Proglacial instrumentation and sampling programs to directly measure suspended sediment concentrations (SSCs) at daily, or preferably hourly or finer sampling intervals (Orwin et al., 2010), over periods longer than one open-channel season are rare in the Arctic (Hasholt, 2016;Hasholt et al., 2006). Consequently, statistical models are relied upon to estimate annual sediment transfer from discontinuous samples of SSC. ...
... We note that such correlations have not been reported by authors of similar models (Irvine-Fynn et al., 2005;Schiefer et al., 2017). The inclusion of temperature variables in both NTU-based models (Table 3), and high performance of numerous meteorological variables in the Chamberlin Creek NTUbased model, suggests that NTU does not represent all sediment eroded by melt processes and rainfall and may under-represent the coarse fraction of sediment transfer, less discernible to the turbidity sensor (Orwin et al., 2010). Our Carnivore Creek NTU-based model (Table 3) is the first Arctic multiple-regression model to incorporate ground temperature as a supplementary predictor of SSC, although ground conditions have previously been related to sediment transfer in the Arctic (Favaro & Lamoureux, 2014;Irvine-Fynn et al., 2005;Syvitski, 2002). ...
Seasonal suspended sediment transfer in glaciated catchments is responsive to meteorological, geomorphological, and glacio‐fluvial conditions, and thus is a useful indicator of environmental system dynamics. Knowledge of multifaceted fluvial sediment‐transfer processes is limited in the Alaskan Arctic–a region sensitive to contemporary environmental change. For two glaciated sub‐catchments at Lake Peters, northeast Brooks Range, Alaska, we conducted a two‐year endeavor to monitor the hydrology and meteorology, and used the data to derive multiple‐regression models of suspended sediment load. Statistical selection of the best models shows that incorporating meteorological or temporal explanatory variables improves performances of turbidity‐ and discharge‐based sediment models. The resulting modeled specific suspended sediment yields to Lake Peters are: 33 (20–60) t km‐2 yr‐1 in 2015, and 79 (50–140) t km‐2 yr‐1 in 2016 (95% confidence band estimates). In contrast to previous studies in Arctic Alaska, fluvial suspended sediment transfer to Lake Peters was primarily influenced by rainfall, and secondarily influenced by temperature‐driven melt processes associated with clockwise diurnal hysteresis. Despite different sub‐catchment glacier coverage, specific yields were the same order of magnitude from the two primary inflows to Lake Peters, which are Carnivore Creek (128 km²; 10% glacier coverage) and Chamberlin Creek (8 km²; 23% glacier coverage). Seasonal to longer term sediment exhaustion and/or contrasting glacier dynamics may explain the lower than expected relative specific sediment yield from the more heavily glacierized Chamberlin Creek catchment. Absolute suspended sediment yield (t yr‐1) from Carnivore Creek to Lake Peters was 27 times greater than from Chamberlin Creek, which we attribute to catchment size and sediment supply differences. Our results provide a foundational understanding of the current sediment transfer regime and are useful for predicting changes in fluvial sediment transport in glaciated Alaskan Arctic catchments.
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... Climate change, human activities, and other perturbations are likely to influence existing patterns of weathering, erosion, transport, and deposition of material across defined landscape components and units (e.g., Warburton, 2007;Orwin et al., 2010;Beylich, 2016aBeylich, , 2016bDixon, 2016a;Zwoliński et al., 2016). While it is still a challenge to develop an improved understanding of how such changes interact and affect slope, fluvial processes, denudation rates, source-to-sink fluxes, and sedimentary budgets, such quantitative analyses promise to be an efficient framework to assess the impact of environmental changes and disturbances to sediment dynamics and to evaluate landscape sensitivity (e.g., Beylich et al., 2006Beylich et al., , 2012Beylich et al., , 2016Warburton, 2007;Slaymaker et al., 2009;Orwin et al., 2010). ...
... Climate change, human activities, and other perturbations are likely to influence existing patterns of weathering, erosion, transport, and deposition of material across defined landscape components and units (e.g., Warburton, 2007;Orwin et al., 2010;Beylich, 2016aBeylich, , 2016bDixon, 2016a;Zwoliński et al., 2016). While it is still a challenge to develop an improved understanding of how such changes interact and affect slope, fluvial processes, denudation rates, source-to-sink fluxes, and sedimentary budgets, such quantitative analyses promise to be an efficient framework to assess the impact of environmental changes and disturbances to sediment dynamics and to evaluate landscape sensitivity (e.g., Beylich et al., 2006Beylich et al., , 2012Beylich et al., , 2016Warburton, 2007;Slaymaker et al., 2009;Orwin et al., 2010). The current knowledge on environmental fluxes, sediment dynamics, and the sediment cascade within Holocene to contemporary climates forms the basis for predicting the consequences of ongoing and future climate change (Beylich, 2016a;Berthling and Etzelmüller, 2016;Molau, 2016;Lane et al., 2017;Morche et al., 2017). ...
... Denudation includes chemical and mechanical processes, and its spatiotemporal variability is controlled by a wide range of environmental drivers (e.g., Warburton, 2007;Beylich, 2016aBeylich, , 2016bBeylich, , 2016cDixon, 2016aDixon, , 2016bZwoliński et al., 2016). Coordinated research efforts and the integration of regional data sets can help to apply and test models of landscape response to climate change and anthropogenic impacts (Beylich et al., 2006(Beylich et al., , 2012Orwin et al., 2010;Beylich, 2016aBeylich, , 2016c. ...
This Special Issueon Drivers of denudation rates, source-to-sink fluxes, and sedimentary budgets produced by the I.A.G./A.I.G. SEDIBUD group (http://www.geomorph.org/sedibud-working-group/) includes selected paper contributions from the 11thWorkshop Relationships between climate change, vegetation cover and sediment fluxes in high-latitude/high-altitude cold environmentsof the I.A.G./A.I.G. SEDIBUD (Sediment Budgets in Cold Environments) program (2005-2017) held in Baru, Romania, 5-8 September 2017, and from the Conference Session S27 Sediment Budgets of the 9th International Conference on Geomorphology (9thICG) held in New Delhi, India, 6-11 November 2017.
... According to common opinion, rivers are characterized by a high rate of fluvial transport (particularly bedload transport), with a tendency toward deposition of transported material and a predomination of downstream aggradation. Measurements of sediment transport in High Arctic rivers reveal a high variability of fluvial transport rates (from 6 × 10 2 to N4 × 10 4 t y −1 ; Orwin et al., 2010), depending on the specific features of the catchment and local weather patterns (Østrem et al., 1967;Church and Gilbert, 1975;Hasholt, 1976;Kjeldsen and Østrem, 1980;Gilbert and Church, 1983;Pearce et al., 2003;Rachlewicz, 2007;Kociuba et al., 2010;Janicki, 2014, 2015;Beylich and Laute, 2015;Kociuba, 2017a), as well as a diversified structure of sediment components with a variable contribution of bedload from b1% to 37% (Orwin et al., 2010) and up to 90% (Carrvick and Heckmann, 2017). ...
... According to common opinion, rivers are characterized by a high rate of fluvial transport (particularly bedload transport), with a tendency toward deposition of transported material and a predomination of downstream aggradation. Measurements of sediment transport in High Arctic rivers reveal a high variability of fluvial transport rates (from 6 × 10 2 to N4 × 10 4 t y −1 ; Orwin et al., 2010), depending on the specific features of the catchment and local weather patterns (Østrem et al., 1967;Church and Gilbert, 1975;Hasholt, 1976;Kjeldsen and Østrem, 1980;Gilbert and Church, 1983;Pearce et al., 2003;Rachlewicz, 2007;Kociuba et al., 2010;Janicki, 2014, 2015;Beylich and Laute, 2015;Kociuba, 2017a), as well as a diversified structure of sediment components with a variable contribution of bedload from b1% to 37% (Orwin et al., 2010) and up to 90% (Carrvick and Heckmann, 2017). ...
After the Little Ice Age, high-latitude proglacial river catchments have been observed to transition to paraglacial conditions through the activation of fluvial processes and changes in the river valley and channel forms. This project provides an analysis of contemporary changes in the morphology of the valley bottom and channel development of the proglacial Scott River catchment (NW part of the Wedel Jarlsberg Land, SW Spitsbergen) based on observations conducted during the 2009–2013 melt seasons. Almost half of the catchment (area of 10 km²) is occupied by a valley glacier, currently in the stage of rapid recession. The processes driving the development of the glacier-free valley floor are determined by (1) long-term factors such as geological structure, glaciotectonics, or the morphogenesis of the terminoglacial zone; (2) medium-term factors, including climatic changes and changes in the extent of the glacial terminus and hydrological regime; and (3) short-term factors such as weather-driven flooding events. Geological factors determined the development of two valley narrowings, and a clear division of the valley floor into three morphological zones. The upper gorge in the terminal moraine rampart distinguishes the wide (up to 700 m) upper section of the valley bottom dominated by an outwash plain, where the river system is fed by small tributaries. The lower valley gorge dissecting the elevated marine terrace separates the middle section of the braided river floodplain from the mouth section (alluvial fan). The geomorphological field mapping of the valley floor and riverbed was conducted using geodesic and hydrometric measurements with high-resolution survey techniques based on the global positioning system (GPS). The detail measurements of the Scott River valley and channel were carried out at representative cross-sections and longitudinal profiles in various parts of the catchment. Because of the dominance of the glacial alimentation regime, changes in the discharge rate and bedload transport regime are influenced by the glacial ablation rate, which determines the variability of channel morphology and the contemporary development of the valley bottom. The upper section of the valley is dominated by a multiple-channel braided system fed by sub- and supraglacial waters, while in the middle section the development pattern changes from a meandering single-thread channel to a multiple-channel wandering system to a multiple-channel braided system. The current valley bottom is almost entirely occupied by a braided river floodplain and multiple-channel river bed. Changes in the channel system are related to periods of snowmelt and the related flooding. After the retreat of the snow cover, the channels are highly stable, as their spatial pattern is usually transformed during several days of ablation or ablation-precipitation flood flows. In the river's mouth section, the channel returns to a single-thread meandering pattern before transitioning to a multiple-channel distribution system and finally to a single-thread straight channel. The river below the ebb in the storm bank develops a subaqual prodelta.
... In these watersheds, SS flux is the result of multiple interacting processes (e.g., temperature, precipitation, and permafrost) that allow for the mobilization, transport, and storage of suspended sediment (Forbes & Lamoureux, 2005). The efficacy of these processes is highly dependent on seasonal phase changes in water, resulting in High Arctic fluvial SS flux being particularly susceptible to climate change (Beylich et al., 2011;Déry et al., 2009;Orwin et al., 2010). As the Arctic warms, it is predicted that High Arctic fluvial SS flux will increase due to changing runoff patterns in response to shifts in precipitation and permafrost temperature (Lewis & Lamoureux, 2010;Syvitski, 2002). ...
Records of fluvial suspended sediment fluxes are sensitive indicators of hydrometeorological and permafrost change. Here we document the watershed‐scale suspended sediment flux response to a period of hydrometeorological change and landscape disturbance in two High Arctic rivers. Net in‐channel and extra‐channel sediment storage and changing hydrometeorological conditions dampen the downstream transport of increased sediment delivery from localized permafrost slope disturbances. Our results show that the impact of permafrost disturbance is likely a smaller effect than a shift toward a pluvially (rainfall) dominated hydrological regime in these environments. Suspended sediment transport is energy limited under contemporary hydrometeorological conditions and the transition from a nival to pluvial dominated flow and sediment transfer regime will likely accelerate landscape change in the High Arctic.
... The sequence development of the upper Haslital-Aare area is typical for alpine settings (Orwin et al. 2010;Schrott et al. 2003;Slaymaker 2008) and highlights the "paraglacial cycle" (Church and Ryder 1972) with initial high erosion and sedimentation rates that diminish once the glacially produced debris is exhausted and geomorphic rates return to background levels (Hinderer 2001;Ballantyne 2002;Lane et al. 2016). Additionally, mass wasting processes dominating the alpine headwaters are gradually replaced by fluvial processes. ...
Climate change and high magnitude mass wasting events pose adverse societal effects and hazards, especially in alpine regions. Quantification of such geomorphic processes and their rates is therefore critical but is often hampered by the lack of appropriate techniques and the various spatiotemporal scales involved in these studies. Here we exploit both in situ cosmogenic 10Be and 14C nuclide concentrations for deducing exposure ages and tracing of sediment through small alpine debris flow catchments in central Switzerland. The sediment cascade and modern processes we track from the source areas, through debris flow torrents to their final export out into sink regions with cosmogenic nuclides over an unprecedented five‐year time series with seasonal resolution. Data from a seismic survey and a 90 m core area revealed a glacially overdeepened basin, filled with glacial and paraglacial sediments. Surface exposure dating of fan boulders and radiocarbon ages constrain the valley fill from the last deglaciation until the Holocene and show that most of the fan existed in early Holocene times already. Current fan processes are controlled by episodic debris flow activity, snow (firn) and rock avalanches. Field investigations, DEMs of difference and geomorphic analysis agree with sediment fingerprinting with cosmogenic nuclides, highlighting that the bulk of material exported today at the outlet of the subcatchments derives from the lower fans. Cosmogenic nuclide concentrations steadily decrease from headwater sources to distal fan channels due to the incorporation of material with lower nuclide concentrations. Further downstream the admixture of sediment from catchments with less frequent debris flow activity can dilute the cosmogenic nuclide signals from debris flow dominated catchments but may also reach thresholds where buffering is limited. Consequently, careful assessment of boundary conditions and driving forces is required when apparent denudation rates derived from cosmogenic nuclide analysis are upscaled to larger regions.
