Water yield and sediment export in small, partially glaciated Alpine watersheds in a warming climate

Micheletti, Natan; Lane, Stuart N.

doi:10.1002/2016wr018774

Cited by 84 publications

(94 citation statements)

References 74 publications

(167 reference statements)

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“…14) and up to 60 % of suspended load has been reported to come from the glacier as opposed to from proglacial hillslopes (Leggat et al, 2015). Micheletti and Lane (2016) have recently shown an (expected) increase in meltwater yield and sediment transport capacity, but an (unexpected) disassociation of sediment yield with these parameters, which they attribute to missing connectivity between rockwalls, hillslopes and the proglacial channel network.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…It is therefore rather unexpected that recent studies have shown that an increase of transport capacity due to enhanced meltwater runoff did not lead to a corresponding increase of sediment flux Micheletti and Lane, 2016). These authors reasoned that a lack of connectivity between (new) hillslope sediment sources and the channel network had developed.…”

Section: Connectivitymentioning

confidence: 99%

“…The index of connectivity (IC) published by Cavalli et al (2013) represents an adaptation of an original index (developed by Borselli et al, 2008) to high mountain areas where high-resolution DEMs exist. This index has been applied to proglacial areas in a semi-quantitative fashion (Goldin et al, 2016;Micheletti and Lane, 2016;Cavalli et al, in review) for the appraisal of…”

Section: Connectivitymentioning

confidence: 99%

“…Micheletti and Lane, 2016) wherever possible to test the hypothesis that proglacial systems are largely transport-limited systems and to examine if such a discrepancy between sediment transport capacity and sediment yield is due to (changes in) proglacial system connectivity.…”

Section: Future Challenges and Opportunitiesmentioning

confidence: 99%

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Short-term geomorphological evolution of proglacial systems

2017

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Proglacial systems are amongst the most rapidly changing landscapes on Earth, as glacier mass loss, permafrost degradation and more episodes of intense rainfall progress with climate change. This review addresses the urgent need to quantitatively define proglacial systems not only in terms of spatial extent but also in terms of functional processes. It firstly provides a critical appraisal of prevailing conceptual models of proglacial systems, and uses this to justify compiling data on rates of landform change in terms of planform, horizontal motion, elevation changes and sediment budgets. These data permit us to produce novel summary conceptual diagrams that consider proglacial landscape evolution in terms of a balance of longitudinal and lateral water and sediment fluxes. Throughout, we give examples of newly emerging datasets and data processing methods because these have the potential to assist with the issues of: (i) a lack of knowledge of proglacial systems within high-mountain, arctic and polar regions, (ii) considerable inter-and intracatchment variability in the geomorphology and functioning of proglacial systems, (iii) problems with the magnitude of short-term geomorphological changes being at the threshold of detection, (iv) separating short-term variability from longer-term trends, and (v) of the representativeness of plot-scale field measurements for regionalisation and for upscaling. We consider that understanding of future climate change effects on proglacial systems requires holistic process-based modelling to explicitly consider feedbacks and linkages, especially between hillslope and valley-floor components.Such modelling must be informed by a new generation of repeated distributed topographic surveys to detect and quantify short-term geomorphological changes.

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Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Connectivitymentioning

confidence: 99%

Section: Connectivitymentioning

confidence: 99%

Section: Future Challenges and Opportunitiesmentioning

confidence: 99%

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Short-term geomorphological evolution of proglacial systems

2017

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“…Huggel et al, 2012;Micheletti and Lane, 2016;Palazón and Navas, 2016). In such environments, three main hydroclimatic forcings drive the processes that contribute to suspended sediment concentration (SSC) along channels: erosive rainfall, glacial melt, and snowmelt.…”

Section: Introductionmentioning

confidence: 99%

Hydroclimatic control on suspended sediment dynamics of a regulated Alpine catchment: a conceptual approach

Costa¹,

Anghileri²,

Molnár³

2018

Preprint

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Abstract.We analyse the control of hydroclimatic factors on suspended sediment concentration (SSC) in Alpine catchments by differentiating among the potential contributions of erosion and suspended sediment transport driven by erosive rainfall, defined as liquid precipitation over snow free surfaces, icemelt from glacierized areas, and snowmelt on hillslopes. We account for the potential impact of hydropower by intercepting sediment fluxes originated in areas diverted to hydropower reservoirs, and by considering the contribution of hydropower releases to SSC. We obtain the hydroclimatic variables from 10 daily gridded datasets of precipitation and temperature, implementing a degree-day model to simulate spatially distributed snow accumulation and snow-ice melt. We estimate hydropower releases by a conceptual approach with a unique virtual reservoir regulated on the basis of a target-volume function, representing normal reservoir operating conditions throughout a hydrological year. An Iterative Input Selection algorithm is used to identify the variables with the highest predictive power for SSC, their explained variance, and characteristic time lags. On this basis, we develop a hydroclimatic multivariate rating 15 curve (HMRC) which accounts for the contributions of the most relevant hydroclimatic input variables mentioned above. We calibrate the HMRC with a gradient-based nonlinear optimization method and we compare its performance with a traditional discharge-based rating curve. We apply the approach in the upper Rhone Basin, a large Swiss Alpine catchment, heavily regulated by hydropower. Our results show that the three hydroclimatic processes -erosive rainfall, icemelt, and snowmeltare significant predictors of mean daily SSC, while hydropower release does not have a significant explanatory power for 20 SSC. The characteristic time lags of the hydroclimatic variables correspond to the typical flow concentration times of the basin. Despite not including discharge, the HMRC performs better than the traditional rating curve in reproducing SSC seasonality, especially during validation at the daily scale. While erosive rainfall determines the daily variability of SSC and extremes, icemelt generates the highest SSC per unit of runoff, and represents the largest contribution to total suspended sediment yield. Finally, we show that the HMRC is capable of simulating climate-driven changes in fine sediment dynamics 25 in Alpine catchments. In fact, HMRC can reproduce the changes in SSC in the past 40 years in the Rhone Basin connected to air temperature rise, even though the simulated changes are more gradual than those observed. The approach presented is this paper, based on the analysis of the hydroclimatic control on suspended sediment concentration, allows the exploration of climate-driven changes in fine sediment dynamics in Alpine catchments. The approach can be applied to any Alpine catchment with a pluvio-glacio-nival hydrological regime and adequate hydroclimatic datasets. 30Hydrol. Earth Syst. Sci. Discuss., ...

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Combined Flow Abstraction and Climate Change Impacts on an Aggrading Alpine River

Bakker

Costa

Silva

et al. 2018

Water Resources Research

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Recent climatic warming and associated glacial retreat may have a large impact on sediment release and transfer in Alpine river basins. Concurrently, the sediment transport capacity of many European Alpine streams is affected by hydropower exploitation, notably where flow is abstracted but the sediment supply downstream is maintained. Here, we investigate the combined effects of climate change and flow abstraction on morphodynamics and sediment transfer in the Borgne River, Switzerland. From photogrammetrically derived historical Digital Elevation Models (DEMs), we find considerable net aggradation of the braided river bed (up to 5 m) since the onset of flow abstraction in 1963. Reaches responded through bed level steepening which was strongest in the upper most reach. Widespread aggradation however did not commence until the onset of glacier retreat in the late 1980s and the dry and warm years of the early 1990s. Upstream flow intake data shows that this aggradation coincided with an increase in sediment supply, although aggradation accounts for no more than 25% of supplied material. The remainder was transferred through the studied reaches. Estimations of bed load transport capacity indicate that flow abstraction reduces transport capacity by 1–2 orders of magnitude. While residual transport rates vary with morphological evolution, they are in the same order of magnitude as the sediment supply rates, which is why significant transport remains. However, the reduction in transport capacity makes the system more sensitive to short‐term (annual) changes in climate‐driven hydrological variability and climate‐induced changes in intake management and sediment delivery rates.

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Water yield and sediment export in small, partially glaciated Alpine watersheds in a warming climate

Cited by 84 publications

References 74 publications

Short-term geomorphological evolution of proglacial systems

Short-term geomorphological evolution of proglacial systems

Hydroclimatic control on suspended sediment dynamics of a regulated Alpine catchment: a conceptual approach

Combined Flow Abstraction and Climate Change Impacts on an Aggrading Alpine River

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