Centimeter-scale mapping of phototrophic biofilms in glacial forefields using visible band ratios and UAV imagery

Roncoroni, Matteo; Mancini, Davide; Kohler, Tyler J.; Miesen, Floreana; Gianini, Mattia; Battin, Tom J.; Lane, Stuart N.

doi:10.1080/01431161.2022.2079963

Cited by 10 publications

(7 citation statements)

References 82 publications

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“…Oblique pictures may hold the advantage along forested areas that there are not as many occlusion effects (Díaz et al., 2020). Further improvements may be achieved with the application of different flight altitudes and circular flight patterns (Roncoroni et al., 2022). However, for such flight settings, a quadrocopter UAV is needed.…”

Section: Discussionmentioning

confidence: 99%

Towards an automated acquisition and parametrization of debris‐flow prone torrent channel properties based on photogrammetric‐derived uncrewed aerial vehicle data

Schmucki

Bartelt

Bühler

et al. 2023

Earth Surf Processes Landf

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Debris flows are a hazard in mountainous regions. Cost‐effective, long‐term studies of debris‐flow torrents, however, are rare, leading to uncertainties in hazard assessment and hazard prevention. Here, we address the question of whether cost‐effective remote sensing techniques can be applied for assessment of mountain torrents and possibly further gather accurate, long‐term information on the evolution of the catchment. Torrents prone to debris flows are often devoid of vegetation in the near channel area and hence can be well captured with photogrammetrically derived methods using uncrewed aerial vehicle (UAV) surveys. The possibility of automatically extracting specific torrent parameters from high‐resolution terrain models, such as cross‐section area or gradient, is investigated. The presented methodology yields continuous and automatically derived geometrical parameters such as torrent bed width, inclination and cross‐section area, which is a major advantage compared with point‐based, often dangerous field surveys. Their cross‐validation with field measurements shows strong agreement. Those parameters are accurate along sharply incised sections with strong limitations along sections with steep adjacent slopes and/or dense vegetation. The information along the torrent allows fast identification of key sections and weak spots which can be precisely evaluated in the field. The study highlights that proper classification of real ground points poses the key challenge. We show that photogrammetric routines to derive a high‐resolution digital terrain model (DTM) are limited in the case of dense vegetation coverage. In such cases, LiDAR surveys have clear advantages even though they are also limited by very dense vegetation. We find that UAV data can be used for an objective method of estimating debris‐flow torrent geometric properties. And the introduced approaches therefore build a stepping stone towards a more comprehensive, reproducible and objective assessment of torrent processes and predispositions. However, ground‐referencing fieldwork remains essential, and further research on remote sensing supported hazard assessment of debris‐flow‐prone torrents is indispensable.

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Section: Discussionmentioning

confidence: 99%

Towards an automated acquisition and parametrization of debris‐flow prone torrent channel properties based on photogrammetric‐derived uncrewed aerial vehicle data

Schmucki

Bartelt

Bühler

et al. 2023

Earth Surf Processes Landf

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“…Twenty‐four of these samples were obtained from different sites in June–July, and 23 were collected in August–September 2019. Due to the highly unstable channels of glacier‐fed streams (Bakker et al 2019; Roncoroni et al 2022, 2023) highlighted in Fig. 1, sampling reaches from both seasons were located at different positions relative to the glacier mainstem channel, and are thus considered independent (Brandani et al 2022).…”

Section: Methodsmentioning

confidence: 99%

Unexpected functional diversity of stream biofilms within and across proglacial floodplains despite close spatial proximity

Michoud,

Kohler,

Peter

et al. 2023

Limnology & Oceanography

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High‐mountain streams are particularly vulnerable to climate change because they intimately interface with the cryosphere. As glaciers shrink and snowpack diminishes, proglacial streams will eventually shift from being glacier‐fed to streams fed by groundwater, snowmelt and precipitation. This shift will affect both the flow regime and physico‐chemical characteristics of streams, possibly also the structure and function of their benthic microbiome. Here, we applied genome‐resolved metagenomics to benthic biofilms from glacier‐fed streams and their groundwater‐fed tributaries within three proglacial floodplains in the Swiss Alps. Despite the close spatial proximity between both stream types, their microbiome structure differed consistently for both prokaryotes and eukaryotes. The glacier‐fed stream microbiome was taxonomically and functionally less diverse than its groundwater‐fed counterpart, and had smaller genomes, but with conservation of the central metabolic functions primarily related to nitrogen and sulfur cycling. Consequently, much higher functional variability was associated with the microbiome of tributary streams, mainly due to abundant genes involved in the transport and degradation of organic matter. Our findings suggest that glacier shrinkage will cause shifts in the functioning of benthic microbiomes of proglacial floodplains with yet unknown consequences for downstream biogeochemistry.

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“…The surface topography was determined using Surface-from-Motion Multi-View Stereo (SfM-MVS) photogrammetry, using imagery acquired with a Dji Phantom Drone, resulting in a final DEM with a 0.25 m resolution and a ± 0.02 m precision. A detailed description of the procedure is provided in Roncoroni et al (2022). The DEM was then resampled to a model grid of 10 by 10 m. In order to estimate the elevation of the water bodies precisely, we isolated the zones in the DEM corresponding to the stream network and performed a separate resampling of these zones only.…”

Section: Structured Discretization (Dis) Node Property Flow (Npf) Sto...mentioning

confidence: 99%

Current and future role of meltwater-groundwater dynamics in a proglacial Alpine outwash plain

Müller

Roncoroni

Mancini

et al. 2023

Preprint

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Abstract. 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.

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Centimeter-scale mapping of phototrophic biofilms in glacial forefields using visible band ratios and UAV imagery

Cited by 10 publications

References 82 publications

Towards an automated acquisition and parametrization of debris‐flow prone torrent channel properties based on photogrammetric‐derived uncrewed aerial vehicle data

Towards an automated acquisition and parametrization of debris‐flow prone torrent channel properties based on photogrammetric‐derived uncrewed aerial vehicle data

Unexpected functional diversity of stream biofilms within and across proglacial floodplains despite close spatial proximity

Current and future role of meltwater-groundwater dynamics in a proglacial Alpine outwash plain

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