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Temperate Alpine glaciers produce substantial quantities of sediment that are exported via active subglacial meltwater channels to their proglacial environments. Measurements of suspended sediment and bedload in proglacial rivers have been used to estimate glacial erosion rates and downstream sediment yields, assuming that eroded sediment is rapidly evacuated by flowing meltwater; that subglacial sediment storage remains constant and that the measurements are unaffected by proglacial filtering effects. Studies generally focus on the suspended sediment fraction of export, due to the challenges involved in monitoring coarse sediment transport. It is not surprising that subglacial sediment transport dynamics are poorly understood, and a limited amount of field and model-based research indicates that subglacial sediment transport may be attenuated in the rapidly thinning and retreating snout marginal zones of many Alpine glaciers. This is likely due to the existence of non-pressurised subglacial channels with highly variable transport competence related to diurnal discharge variability, leading to cycles of alluviation and deposition. The potential attenuation of sediment and the unknown relationship between suspended load and bedload has important consequences for estimates of glacial erosion based on proglacial export measurements. Here, we present results from a proof-of-concept for a method to track radio-tagged bedload particles through meltwater channels under shallow temperate glacier ice (

Large Alpine glaciers typically export significant quantities of subglacially eroded sediment to their downstream environments via meltwater streams. The supply of this glaciogenically-produced sediment has an extensive impact on landform genesis and evolution; downstream ecology and ecosystem succession; river morphology and flood risk management; hydropower installations and industrial sediment extraction. However, little is known about the processes and mechanisms driving the entrainment and evacuation of subglacial sediment by meltwater flow. Controls on the rate of sediment export remain poorly constrained, limiting the reliability of future sediment yield predictions. Although the fine (suspended) fraction of meltwater-borne subglacial sediment export is relatively well studied, records of suspended sediment load are commonly obtained from distal proglacial locations and may consequently be affected by filtering effects in proglacial rivers and forefields. Additionally, almost nothing is known about the coarse (bedload) component and its relationship to suspended sediment transport due to the difficulties in monitoring bedload flux. In this study, we present a first-of-its-kind dataset from Glacier d’Otemma, Switzerland, capturing three years (2020, 2021 and 2022) of continuous suspended sediment load, bedload and water discharge data from a monitoring site immediately in front of the glacier meltwater portal. Measurements of coarse sediment flux were performed using recently developed environmental seismological monitoring techniques. Data from all three years show that bedload delivery to the glacier margin switches from being transport-limited to being supply-limited during the melt season and was driven by snow-line retreat. Bedload evacuation reduces to very low levels as soon as the snow-line reaches the upper parts of the glacier, which it does increasingly often due to climate warming. We hypothesise that the position of the snow line controls the degree of channelisation – or the efficiency – of the subglacial drainage network above and below it, with consequences for both sediment availability and channel competence. Meltwater in the non-channelised parts of the glacier struggles to transport bedload. As the channelisation develops, accumulated bedload is evacuated until the point at which the subglacial channel network reaches its maximum extent or, due to progressive channel division in a dendritic network, is developing channels that are too small to readily transport it. Thus, recent reports of increases in bedload yield from Alpine glaciers may not reflect increases in glacial erosion but simply an increase in the upstream elevation of snow-lines, the associated subglacial channelization and hence subglacial bedload export capacity.

Alpine glaciated catchments are rapidly changing with glacier retreat. Combined with future earlier snow melt and more liquid precipitation, the importance of high alpine catchments to provide essential water resources for downstream uses will increase. In this context, groundwater storage may play a critical role in maintaining baseflow during drought events. In this study, we provide an overview of the hydrogeological functioning of the Otemma glacier catchment, a typical glaciated catchment in the Swiss Alps. Based on three years of field data, we provide a complete conceptual model of the volumes and timescales at which different landforms store and release water and compare those results with a catchment-scale analysis of the winter discharge recession. Based on water isotopes and geochemical data, we show the strong spatial heterogeneity in the water sources that recharge those landforms and how they are interconnected. Finally, we present results of a 3D model of the groundwater-surface water interactions in the proglacial outwash plain, discuss where potential new floodplains may form in the future and show a rather limited potential storage of the order of 20 mm. We conclude that superficial landforms have a limited potential to provide significant baseflow for downstream users but can provide significant moisture for high alpine ecosystems. Nevertheless, we show that bedrock infiltration likely represents the largest groundwater reservoir but more research is needed to characterize its role in the future.

The thermal regime of regulated rivers is altered by rapid discharge variation downstream of hydropower plants (hydropeaking). This strongly modifies the thermal regime of such rivers, due to both the upstream water storage and the associated regular release to downstream, resulting in a thermal wave as the water temperature is different from the river temperature (thermopeaking). This temperature alteration needs to be considered when managing hydropower installations because of its influence on the health of aquatic ecosystems. On a longer timescale, global climate change is also influencing the natural thermal regime of rivers through changes in air temperature, vegetation, hydrology, etc. Thus, the assessment of the effects of hydropower on streams needs also to consider the extent to which changing climate will modify existing hydropower impacts, and also the mitigation methods that have been developed for current climate situations.To evaluate the evolution of river temperature under different scenarios, deterministic coupled, hydrodynamic and temperature modelling can be used. Such models have been used previously to replicate the thermal regime of rivers or evaluate the impact of climate change on river temperature. However, there is a growing realisation that external drivers of stream temperature are more complex than hitherto thought, especially in per-Alpine streams. For instance, such streams can have significant shading whose importance changes as a function of time within the year. Equally, between the zone of water off-take and return, the residual flow may not occupy the full channel perimeter meaning that it is also necessary to consider the energy balance effects of water-adjacent sediments.To address this challenge this paper identifies the necessary ingredients of deterministic coupled hydrodynamic and temperature modelling for hydropower impacted streams. This is supported by a unique and very high-quality stream temperature dataset which we use to identify the minimum process representation required for such models. In order to reproduce such data, we show that such models need to have a spatially-explicit and time-dependent correction of two key processes: (1) solar shading; and (2) stream bed sediment effects.

By growing awareness for and interest in climate change, media coverage enlarges the window of opportunity by which research can engage individuals and collectives in climate actions. However, we question whether the climate change research that gets mediatized is fit for this challenge. From a survey of the 51,230 scientific articles published in 2020 on climate change, we show that the news media preferentially publicizes research outputs found in multidisciplinary journals and journals perceived as top-tier. An in-depth analysis of the content of the top-100 mediatized papers, in comparison to a random subset, reveals that news media showcases a narrow and limited facet of climate change knowledge (i.e., natural science and health). News media selectivity reduces climate change research to the role of a sentinel and whistleblower for the large-scale, observed, or end-of-century consequences of climate change for natural Earth system components. The social, economic, technological, and energy aspects of climate change are curtailed through mediatization, as well as local and short-term scales of processes and solutions. Reviewing the social psychological mechanisms that underlie behavioral change, we challenge the current criteria used to judge newsworthiness and argue that the consequent mediatization of climate change research fails to breed real society engagement in actions. A transformative agenda for the mediatization of climate change research implies aligning newsworthiness with news effectiveness, i.e., addressing the extent to which communication is effective in presenting research that is likely to produce behavioral change.

Glaciated alpine catchments are rapidly evolving due to glacier retreat and consequent geomorphological and ecological changes. As more terrain becomes ice free, the interactions between surface and subsurface waters become gradually more significant, leading to potential changes in water storage and release, which in turn may impact ecological, geomorphological and hydrological processes. In this study, we aim to understand the hydrological functioning of outwash plains as glaciers retreat. These constitute a fluvial aquifer which appears as a focal point for water storage and alpine ecology and their dynamics have only rarely been studied. Based on geophysical investigations as well as year-round stream and groundwater observations, we developed a simplified physically-based 3D MODFLOW model and performed an optimized automatic calibration using PEST HP. By comparing the model results to field observations, we highlight the strong interactions between the upstream river and the aquifer, with stream infiltration being the dominant process of recharge. Groundwater exfiltration occurs in the lower half part of the outwash plain, balancing out the amount of river infiltration at a daily time scale. We show that hillslope contributions from rain and snow-melt have little impact on groundwater levels. We also show that outwash plain aquifers can maintain groundwater levels close to the surface even during long dry periods. From a hydrological perspective, we finally explore how new outwash plains may form in the future due to glacier recession and discuss what cascading impact the presence of multiple outwash plains may have in such catchments. We estimate the total dynamic storage of future outwash plains to be about 20 mm and we demonstrate their limited capacity to produce more stream water than what they infiltrate upstream, except for very low river flows (< 150 to 200 L s−1). Below this limit, they can provide limited baseflow on timescales of weeks, thus maintaining some moisture conditions potentially beneficial for proglacial ecosystems. Their role in attenuating floods also appears limited, as less than 0.5 m3 s−1 of river water can be infiltrated. Outwash plains appear therefore to play an important role for alpine ecosystems but have marginal hydrological effects on downstream river discharge.

The rapid recession of glaciers is exposing large zones to the development of embryonic phototrophic ecosystems and eventual ecological succession. Traditionally, succession patterns in glacial forefields have been seen as a response to time since deglaciation, but nowadays forefield exposure is so rapid that this theory may be less applicable. In this suc-cession process, periphyton are potential pioneer organisms because of their role in modifying the local environment (e.g. access to water) to create conditions conducive to plant colonization. In this paper, we aim to decrypt the physical properties of the habitats that define the spatial and temporal assemblage of periphyton during the melt-season of an Alpine temperate glacier in the context of rapid climate change. We show that periphyton develop in glacial flood -plains throughout the melt-season and could extend to cover significant surfaces. However, development is only pos-sible when the combined conditions of stability and water accessibility are met. In glacial floodplains, stable zones exist and are typically located on terraces; but they can also be locally found for much shorter periods in the more ac-tive, glacial-stream reworked zone. On terraces, water accessibility can be a limit due to well-drained sediments, but when present, often aided by the role that biofilms play in creating an impermeable layer, it provides a stable and clear water source that biofilms could exploit. In the active part of the braid plain, whilst water availability is very high, the water is harsh (low temperature, high turbidity) and erosive. Therein, periphyton can rapidly exploit short windows of opportunity but the habitat conditions rarely remain stable for long enough for continuous periphyton cover to develop. Thus, the role of periphyton in ecosystem succession is strongly conditioned by the spatial extent of the active zone, itself a function of high rates of glacier melt and sediment supply associated with rapid glacier retreat.

Glaciated catchments in the Swiss Alps are subject to intense changes due to rapid glacier retreat. Combined with earlier snowmelt, water availability in summer and especially during drought periods will become limited, which will have a strong influence on the local ecology but also for downstream water usages.Water stable isotopes have become a commonly used tracer in hydrological studies to separate the contribution of snow and rain, due to their distinct signature and conservative behaviour, but also due to their simple sampling procedure and low analysis costs. In high alpine catchments, their application is however challenging because the temporal and spatial isotopic composition of ice and snow varies strongly (which requires intense sampling) and because their isotopic signal range is often strongly overlappingBased on a case study of a glaciated catchment in the Swiss Alps, we propose in this study to compare the estimation of snow and ice melt contribution using two separate approaches: a glacier surface mass balance modelling approach, and a separation using a large database of isotopic observations. We show the large spatial and temporal variation of the snow isotopic signal at the catchment scale and propose a simple modelling approach to reconstruct its temporal evolution. On this basis, we show that snow and ice melt isotopes show very similar ranges of values during the summer due to the effect of rain on snow and snow fractionation. As a result, it appears that the estimation of their respective contribution is very sensitive to the accuracy of the estimated snow melt end-member. In comparison, the mass balance modelling approach may provide more robust results but requires a more field intensive work in order to measure snow accumulation and ice ablation. Finally, we insist that water stable isotopes should only be used with a proper statistical assessment of their spatial variability and a proper characterization of their temporal evolution in order to provide any realistic estimations in glaciated catchments.

1) Primary production is a fundamental ecosystem process that influences nutrient and carbon cycling, and trophic structure in streams. The magnitude and timing of gross primary production (GPP) are typically controlled by hydrology, light, nutrient availability and grazers. Estimates of GPP and its drivers in high-mountain streams remain elusive at present. 2) We estimated GPP in streams typical for high-mountain catchments, namely a glacier-fed, groundwater-fed (krenal) and a snowmelt-fed (nival) stream. Using high-resolution sensor data over 2 years in combination with numerical simulations of stream hydraulics, we studied the periods of GPP characteristic for these streams, as well as their major drivers. 3) Favourable windows for GPP were constrained to periods at the onset of the snowmelt and its recession, when photosynthetic active radiation at the streambed and streambed stability facilitated GPP. 4) During these windows of opportunity, GPP was higher in the nival stream (3.7 ± 3.4 g O2 m−2 day−1), followed by the glacier-fed (1.5 ± 1.6 g O2 m−2 day−1) and the krenal streams (0.6 ± 0.6 g O2 m−2 day−1). GPP was largely controlled by photosynthetic active radiation at the stream bottom, however, we were not able to establish an unequivocal relationship between flow-induced bed movement and GPP. 5) Our results highlight the capacity of primary producers to exploit the discrete and relatively predictable windows of opportunities in high-mountain streams. We propose that climate-driven change in snow and glacier melt reduction may ameliorate stream environmental conditions, thereby enhancing the potential autochthonous organic matter supply within the catchment.

Flash floods occur quickly and instantly with respect to triggering rainfall and are particularly frequent in river basins of limited extent. In the Mediterranean area, flash floods are acknowledged as the most widespread geo-hydrological hazard. They may have a particularly catastrophic character due to combination of intense precipitation and strong orographic forcing (cumulative rainfall values in the order of hundreds of mm in a few hours) with the widespread presence of steep, small river basins, referred to as Small Mediterranean Catchments. The natural susceptibility associated with Small Mediterranean Catchments eventually results in high hydrogeological risk notably for densely-urbanized and populated alluvial fans at catchment outlets. Therefore, the evaluation of sediment budgets of flash-flood prone, torrential catchments is important for the assessment of flood susceptibility and hazard in piedmont areas.Our study addresses the evaluation of the sediment volume that has the potential to be entrained and delivered downstream during flash floods in torrential catchments. With the final aim of developing an approach useful to the definition of the order of magnitude of future flash flood events in terms of debris loads, our goal is to obtain reliable quantification of sediment storage through the geomorphological analysis of high-resolution topographic data.We developed and tested a predictive, quantitative geomorphological technique for estimating the magnitude of debris flows related to flash floods triggered by extreme rainfall events. We applied our method to steep torrential catchments that (i) are underlain by resistant rocky bedrock, therefore not prone to large landslides, and (ii) allowed testing of our technique through quantification of the effects of recently-occurred flash floods. The three study catchments are located in southern Italy and experienced flash flood-related debris flows triggered by a rainstorm with a recurrence interval > 200 yrs. We estimated the sediment volumes stored in the investigated mountainous catchments prior to the flash flood and compared our results with the sediment volumes entrained by the debris flows. The latter volumes were estimated by post-event data collected by means of both field surveys and remote sensing (drone surveys). The results were mutually consistent so supporting our approach. The approach can be applied extensively, even in the absence of field data and measurements, to ungauged catchments similar to those we analysed for flash flood hazard assessment and planning of mitigation strategies.

Microbial biofilms have received great attention in the last few decades from both aquatic ecologists and biogeomorphologists. Most recently, this has focused on mapping biofilms to understand their spatial distributions and ecosystem services. Such studies often involve the use of satellite imagery, which typically provides large temporal and spatial scales and wide-range spectral information. Although satellites have the advantage of multi- and hyper-spectral sensors, images often have low spatial resolution that limits their use in river studies, where both rivers are narrower and stream processes occur at resolutions smaller than the footprint of satellite sensors. Spatial resolution is sensor quality dependent but also controlled by sensor elevation above the ground. Hence, high resolutions can be achieved either by using a very expensive sensor or by decreasing the distance between the target area and the sensor itself. To date, sensor technology has advanced to a point where multi- or even hyper-spectral cameras can be easily carried out by an Uncrewed Aerial Vehicle (UAV) at unprecedented spatial resolutions. Where such sensors have high spectral resolution, they are often prohibitively expensive, especially as their use in extreme environments such as glacial forefields risks UAV damage. In this paper, we test the performance of visible band ratios in mapping biofilms in an Alpine glacier forefield characterized by a well-developed and heterogeneous stream ecosystem but using a low-cost UAV. The paper shows that low-cost and consumer grade UAVs can be easily deployed in such extreme environments, delivering both quality RGB images for photogrammetric (SfM-MVS) processing and sufficient spectral information for benthic biofilm mapping at high temporal and spatial resolution. RGB cameras are an alternative to expensive multi- or hyper-spectral cameras.Phototrophic biofilms can be detected and mapped through visible band ratios.High-temporal and high-resolution imagery can be collected by consumer-grade UAVs.Biofilm presence is restricted to stable and water-fed terraces in summer. RGB cameras are an alternative to expensive multi- or hyper-spectral cameras. Phototrophic biofilms can be detected and mapped through visible band ratios. High-temporal and high-resolution imagery can be collected by consumer-grade UAVs. Biofilm presence is restricted to stable and water-fed terraces in summer.

Studying subglacial drainage networks is important for understanding the potential relationship between channel dynamics and rapid glacier recession as well as the role of subglacial channels in subglacial sediment evacuation. In order to delineate the planform geometry of snout marginal subglacial channels, densely spaced ground-penetrating radar (GPR) measurements at a frequency of ~70 MHz were carried out over the snout marginal zones of two temperate glaciers in the southwestern Swiss Alps, the Haut Glacier d'Arolla and the Glacier d'Otemma. Three-dimensional (3-D) data processing and amplitude analysis of the GPR reflection along the glacier bed was used to map the channels. At the Haut Glacier d'Arolla, two relatively straight channels of several meters in width were identified. The positions of these channels correspond well with the locations of channel outlets at the glacier terminus, as well as with fractures appearing on the glacier surface one month after the GPR data acquisition. The latter are believed to represent the beginning of ice collapse above the subglacial channels. At the Glacier d'Otemma, a major subglacial conduit was detected with similar dimensions to those identified at the Haut Glacier d'Arolla, but greater sinuosity. The position of this channel was confirmed by drone-based imagery acquired after glacier margin collapse. Our results confirm that high-density 3-D GPR surveys can be used to map subglacial channels near temperate alpine glacier margins.

The temporal variability in sediment export yield from glaciers over a timescale of multiple glacial cycles (e.g. 1 × 102 − 1 × 106 years) is of interest for a wide range of applications in glaciology, sedimentology, geomorphology, climatology and environmental engineering. However, the time required for the products of glacial erosion to be transferred through glaciated catchments and the extent to which glacially-conditioned sediment can be transiently stored within them are still poorly constrained and a matter of debate within the community. We propose a conceptual model of the variability in sediment exported from glaciers over multiple glacial cycles based on a literature review. Sediment yield is likely to be highly variable through a glacial cycle, notably between phases of glacier advance, retreat and re-advance due to changes in ice velocity and erosion rates, ice and meltwater transport capacity, and in glacially-conditioned sediment accessibility at the bed. Typically, early phases of glacier retreat and re-advance are expected to lead to the highest increase in sediment yield due to the ease with which the products of bedrock erosion can be accessed and reworked. In contrast, later phases of glacial (re)advance, once glacially-conditioned sedimentary sources become exhausted, may be characterized by intermediate rates of sediment export yield maintained through bedrock erosion. The latest phases of deglaciation, once glacially-conditioned sedimentary sources are either exhausted, stabilized or disconnected from active processes of sediment transfer, are likely to have the lowest rate of export. The conceptual model proposed in this paper fills a gap in the literature by developing a continuous pattern of sediment yield rate variability over the course of multiple glacial cycles, with wider implications for future research. However, its systematic applicability to various glacier settings and glaciations needs more field and modeling data to validate it.

As the climate warms, increases in glacier melt and altered glacier dynamics will result in changes to the dynamics of the Greenland Ice Sheet, impacting the sediment delivery in these rivers. In turn, examining the processes by which proglacial rivers transport sediment delivered by the ice sheet has important implications for the delivery of sediment to the oceans. Applying current knowledge of sediment transport from glacially-fed catchments in alpine regions is difficult, given several pronounced differences compared to glacially-fed catchments in the Arctic. These differences include elevated water discharge and reduced amplitude in diurnal variations of water discharge. Thus, it is imperative that we understand the differences in sediment dynamics between these two regions and evaluate the processes responsible for sediment transport between the ice sheet and ocean. To pursue this understanding, we installed seismic stations to measure bedload transport near the terminus of Russell Glacier during the summer of 2021. We convert the seismic signal from these stations to a bedload transport rate by evaluating several environmental variables, including the transported grain size and ground properties near the river. One station was close to the glacier, whilst the other is 1.5 km downstream. The distance between the stations allows us to evaluate the timing of proglacial sediment transport and deposition. Additionally, the operation of the instruments from early June through mid-August allows us to evaluate seasonal characteristics in sediment discharge. Lastly, we compare these results to the current knowledge of sediment transport from glacierized catchments in mountain regions.

Understanding and predicting bedload transport is an important element of watershed management. Yet, predictions of bedload remain uncertain by up to several order(s) of magnitude. In this paper, we use a five-year continuous time-series of streamflow and bedload transport monitoring in a 13.4 km2 snow-dominated Alpine watershed in the Western Swiss Alps to investigate the hydrological drivers of bedload transport. Following a calibration of the bedload sensors, and a quantification of the hydraulic forcing of streamflow upon bedload, a hydrological analysis is performed to identify daily flow hydrographs influenced by different hydrological drivers: rainfall, snow-melt, and mixed rain and snow-melt events. We then quantify their respective contribution to bedload transport. Results emphasize the importance of mixed rainfall and snow-melt events, for both annual bedload volumes (77% in average) and peaks in bedload transport rate. Results further show that a non-negligible amount of bedload transport may occur during late summer and autumn storms, once the snow-melt contribution and baseflow have significantly decreased (9% of the annual volume in average). Although rainfall-driven changes in flow hydrographs are responsible for a large majority of the annual bedload volumes (86% in average), the identified melt-only events also represent a substantial contribution (14 % in average). Through a better understanding of the bedload magnitude-frequency under different hydrological conditions, the results of this study may help to improve current predictions of bedload transport, and we further discuss how bedload could evolve under a changing climate through its effects on Alpine watershed hydrology.

Proglacial measurements of subglacial sediment export by meltwater are commonly used to estimate glacial erosion rates. Such estimates generally assume that subglacial meltwater flow is the dominant agent driving export and that eroded sediment is rapidly conveyed through subglacial drainage networks to the glacier outlet in efficient channels with large and generally-unsatisfied transport capacities. However, understanding of sediment transport processes under glaciers is limited, especially in the thin, snout-marginal zones of retreating temperate Alpine glaciers.A growing body of field and model-based research from such systems challenges the theory that eroded sediment is rapidly evacuated. Conversely, Alpine glaciers develop intense diurnal and seasonal discharge variation leading to highly variable sediment transport competence and the moderation of sediment export by associated cycles of alluviation. This has important consequences for the timescales over which sediment export can be used as a reliable proxy for glacial erosion, though the problem remains that very little is known about when and under what conditions a glacier margin is capable of evacuating the sediment supplied to it.This study attempts to elucidate sediment transport mechanisms and timescales in the main snout-marginal subglacial channel of glacier d’Otemma, Switzerland, by tracking 324 cobble-sized particles tagged with 433 MHz active radio transponders over the mid-to-late 2021 melt season. Tagged particles were injected into the channel via a 48 m deep borehole and were then tracked over a 350 m subglacial reach and a 150 m proglacial reach with a mobile antenna and stationary antenna arrays.Only 86 particles (27%) were exported in 2021. Preliminary analyses indicate that cobble-sized particles generally have extended residence times in snout marginal zones (weeks to months), with no clear effect of particle size, shape or density on overall transport velocities. Ongoing work involves the daily localisation of particles using a signal strength-based algorithm, providing a unique record of the down-glacier transport of coarse particles in a subglacial channel. Repeat measurements will follow in 2022.

Stable isotope analyses (δ18O, δ2H) combined with the tree-ring dating have enormous potential for tracing freshwater resource availability under changing climate and in the context of the impacts of other human activities. This study focusses on the isotopic composition of tree-rings in combination with an anatomical analysis of the European Larch (Larix Decidua) species from different upstream and downstream sites along the Turtmänna river in south-western Switzerland. The results show distinctive patterns of year-to-year tree-ring growth from their constructed chronology dated back to 1851 (i.e. a 170-year record). A trend of a decreasing growth was noted over the last two decades. Decreasing growth was correlated (r = 0.50) with a decrease in precipitation and an increase in temperature (r = 0.30) during the growing season (between June and October) of previous and current years. The isotopic analysis shows a depletion in 18O in the trees fed by glacial meltwater close to the river as compared to the trees fed by precipitation distal to the river. Given the changes in climate, trees closer to the river are becoming more dependent on river-derived water, which in turn is sourced from melting glaciers. This hence has important consequences for the hydropower generation and water availability.

With a rapid increase in the use of low-cost DIY Arduino solutions, many companies are providing low cost sensors for practically any environmental applications and new users can also benefit from a rich virtual community proposing diverse solutions and tutorials. Nowadays, these new hardware solutions, as well as more robust communication protocols, allow to design very simple almost plug-and-play automatic dataloggers.In this talk we will discuss three simple datalogger solutions developed in the framework of a field campaign in a harsh proglacial environment in the Swiss Alps. The first solution consists of a simple autonomous datalogger (based on Seeeduino Stalker board) designed to record piezometric heads in wells, even during the winter cold season. The second station consists of two alternative main boards (SODAQ and CubeCell) that were used to develop a connected LoRaWAN automatic weather station to monitor air temperature and precipitation on the glacier. Connected to a base station LoRaWAN gateway (Dragino), this system successfully allowed for a remote monitoring of those parameters.In a first step, we will quickly go through the main components of each system and detail the basic LoRaWAN architecture. We will then mostly focus on the practical deployment of these solutions in the field and discuss their potential and challenges. We will try to show a live demonstration of their functioning and will insist on the relative technical simplicity and low-cost of such solutions, which could be replicated for many other environmental applications. We will finally discuss the pros and cons of these solutions compared to professional senor companies.

Rapid glacier retreat leads to the emergence of new rocky landscapes. The common assumption of the presence of bare bedrock underlying glaciers and the closely related assumption that glacier and snow melt manifest themselves essentially as surface runoff, is challenged by the rapid sediment accumulation and the formation of geomorphological landforms where water may be infiltrated and stored. Although some studies have provided rough estimates of groundwater storage and release in high elevation catchments, the actual reservoirs providing baseflow discharge are difficult to identify. While the combined effect of future glacier decline and earlier snowmelt are well recognized, it remains unclear how the rapid hydrogeomorphological transformations will modify the potential groundwater stores.In this study we will provide results of a case study of a glaciated catchment in the Swiss Alps. Firstly, we will discuss, based on a simple modelling approach, the hydrological functioning of different landforms and show to which extend each hydrological unit is currently contributing to groundwater storage. We will then focus on a detailed assessment of the hydrological dynamics of an outwash plain using a 3D Modflow modelling approach. We will show how such a small fluvial aquifer is connected to other landforms and how it can maintain high storage during much longer time scales than other landforms due to strong river-groundwater interactions. Even though the current storage of the outwash plain is limited, we will discuss how glacier retreat may increase its relative contribution in the future. Finally, we will focus on the remaining unidentified storages in our field study and we will provide some geochemical analysis of their potential location and finally conclude with a summary of the hydrogeological functioning of a rapidly deglaciating proglacial catchment.

Emergency responders must reach urgent cases within mandatory timeframes, regardless of weather conditions. However, flooding of transport networks can add critical minutes to travel times between dispatch and arrival. Here, we explicitly model the spatial coverage of all Ambulance Service and Fire and Rescue Service stations in England during flooding of varying severity under compliant response times. We show that even low-magnitude floods can lead to a reduction in national-level compliance with mandatory response times and this reduction can be even more dramatic in some urban agglomerations, making the effectiveness of the emergency response particularly sensitive to the expected impacts of future increases in extreme rainfall and flood risk. Underpinning this sensitivity are policies leading to the centralization of the Ambulance Service and the decentralization of the Fire and Rescue Service. The results provide opportunities to identify hotspots of vulnerability (such as care homes, sheltered accommodation, nurseries and schools) for optimizing the distribution of response stations and developing contingency plans for stranded sites.

Unmanned aerial vehicles (UAVs) and structure-from-motion photogrammetry enable detailed quantification of geomorphic change. However, rigorous precision-based change detection can be compromised by survey accuracy problems producing systematic topographic error (e.g. 'doming'), with error magnitudes greatly exceeding precision estimates. Here, we assess survey sensitivity to systematic error, directly correcting topographic data so that error magnitudes align more closely with precision estimates. By simulating conventional grid-style photogrammetric aerial surveys, we quantify the underlying relationships between survey accuracy, camera model parameters, camera inclination, tie point matching precision and topographic relief, and demonstrate a relative insensitivity to image overlap. We show that a current doming-mitigation strategy of using a gently inclined ( 0 center dot 3 m, representing accuracy issues an order of magnitude greater than precision-based error estimates. For higher-relief topography, and for nadir-imaging surveys of the lower-relief topography, systematic error was

The confluence of rivers is characterized by highly complex internal processes. The hydrodynamic aspects of river confluences have received a lot of attention in recent years. For modeling purposes, it is generally assumed that the water densities of the rivers under consideration are close, and the density effects associated with their difference are neglected. In this approximation, we have previously investigated the confluence of the Vishera and Kama rivers. However, in some cases, the temperatures or salinity of the waters of merging rivers can differ significantly, and thereby the hydrodynamic mechanisms of mixing change considerably. In this paper, we examine the specific features of river confluences with and without taking into account density effects and by comparing both real and simplified channel (river) geometries. Simulations show that, at the density Froude number ∼1 which is observed in the rivers under consideration at the difference in salt concentration ~0.3 g/L, the mixing characteristics of these flows significantly change when they merge. The denser waters of the Vishera river begin to move under the less mineralized waters of the Kama river. As the Froude number exceeds the critical value, a fundamental rearrangement of coherent transverse structures occurs. These effects are more pronounced for the simplified model channel configuration, since taking into account the bottom heterogeneity significantly enhances vertical mixing. Earlier, the phenomenon in which the denser flow moves under the less dense flow was discovered by the authors for the confluence of the Chusovaya and Sylva rivers located in the backwater from the Kama hydroelectric power station.

Glacier shrinkage opens new proglacial terrain with pronounced environmental gradients along longitudinal and lateral chronosequences. Despite the environmental harshness of the streams that drain glacier forelands, their benthic biofilms can harbor astonishing biodiversity spanning all domains of life. Here, we studied the spatial dynamics of prokaryotic and eukaryotic photoautotroph diversity within braided glacier-fed streams and tributaries draining lateral terraces predominantly fed by groundwater and snowmelt across three proglacial floodplains in the Swiss Alps. Along the lateral chronosequence, we found that benthic biofilms in tributaries develop higher biomass than those in glacier-fed streams, and that their respective diversity and community composition differed markedly. We also found spatial turnover of bacterial communities in the glacier-fed streams along the longitudinal chronosequence. These patterns along the two chronosequences seem unexpected given the close spatial proximity and connectivity of the various streams, suggesting environmental filtering as an underlying mechanism. Furthermore, our results suggest that photoautotrophic communities shape bacterial communities across the various streams, which is understandable given that algae are the major source of organic matter in proglacial streams. Overall, our findings shed new light on benthic biofilms in proglacial streams now changing at rapid pace owing to climate-induced glacier shrinkage.

Secondary circulation in river confluences results in a spatial and temporal variation of fluid motion and a relatively high level of morphodynamic change. Acoustic Doppler current profiler (aDcp) vessel-mounted flow measurements are now commonly used to quantify such circulation in shallow water fluvial environments. It is well established that such quantification using vessel-mounted aDcps requires repeated survey of the same cross-section. However, less attention has been given to how to process these data. Most aDcp data processing techniques make the assumption of homogeneity between the measured radial components of velocity. As acoustic beams diverge with distance from the aDcp probe, the volume of the flow that must be assumed to be homogeneous between the beams increases. In the presence of secondary circulation cells, and where there are strong rates of shear in the flow, the homogeneity assumption may not apply, especially deeper in the water column and close to the bed. To reduce dependence on this assumption, we apply a newly-established method to aDcp data obtained for two medium-sized (~60–80 m wide) gravel-bed river confluences and compare the results with those from more conventional data processing approaches. The comparison confirms that in the presence of strong shear our method produces different results to more conventional approaches. In the absence of a third set of fully independent data, we cannot demonstrate conclusively which method is best, but our method involves less averaging and so in the presence of strong shear is likely to be more reliable. We conclude that it is wise to apply both our method and more conventional methods to identify where data analysis might be impacted upon by strong shear and where inferences of secondary circulation may need to be made more cautiously.

Alpine glacier retreat has increased markedly since the late 1980s and is commonly linked to the effects of rising air temperature on surface melt. Less considered are processes associated with glacier snout-marginal surface collapse. A survey of 22 retreating Swiss glaciers suggests that collapse events have increased in frequency since the early 2000s, driven by ice thinning and reductions in glacier-longitudinal ice flux.Detailed measurement of a collapse event at one glacier with Uncrewed Aerial Vehicles and ablation stakes showed 0.02 m/day vertical surface deformation above a meandering main subglacial channel, the planform of which was mapped with Ground Penetrating Radar measurements. However, with low rates of longitudinal flux (

Human activities have increasingly strong impacts on the sediment dynamics of watersheds, directly, for example through water abstraction and sediment extraction, but also indirectly through climate change. This study aims at disentangling these impacts on natural sediment fluxes for the Borgne River, located in the Alps of southwest Switzerland, using two approaches: First, an assessment of contemporary sediment sources and their relative contribution to the sediment delivered to the catchment outlet is undertaken by geochemical fingerprinting and a mixing model. Second, a spatially distributed conceptual model of suspended sediment production and transfer is used to quantify the contribution of different portions of the catchment to the total sediment yield. The model describes the influence of hydroclimatic variables (rainfall, snowmelt, and ice melt), water diversions and reservoir trapping on the sediment yield accounting for the erodibility of the different land covers present in the catchment. The analysis of different scenarios based on this conceptual model aids the interpretation of the fingerprinting results and the identification of the most important factors controlling sediment fluxes. Although the conceptual model overestimates the contribution of the downstream source area and underestimates the contribution of the upstream source area, the results allow us to qualitatively assess the impacts of different drivers influencing the sediment yield at the catchment scale. The results suggest: (1) high sediment yield from the uppermost part of the catchment due to sediment delivery by glacial ice melt; (2) delayed sediment transfer from areas impacted by water abstraction; and (3) reduced sediment contribution from areas upstream of a major hydropower reservoir that intercepts and traps sediment. Although process (1) and processes (2) and (3) serve to counter one another, our study emphasizes that the relative impacts of Anthropocene climate change and human impacts on sediment delivery may be disentangled through multi‐proxy approaches. © 2019 John Wiley & Sons, Ltd.

Rebecca Lave, Christine Biermann, and Stuart N. Lane, eds. London, UK: Palgrave, 2018. xxxii and 594 pp., maps, photos, diagrams, illustrations, notes, bibliography, index. $239.00 cloth (ISBN 978-...