scholarly journals Drainage of an ice-dammed lake through a supraglacial stream: hydraulics and thermodynamics

2021 ◽  
Vol 15 (11) ◽  
pp. 5133-5150
Author(s):  
Christophe Ogier ◽  
Mauro A. Werder ◽  
Matthias Huss ◽  
Isabelle Kull ◽  
David Hodel ◽  
...  
Keyword(s):  
Friction Factor ◽  
Field Measurements ◽  
Swiss Alps ◽  
Water Volume ◽  
Lake Volume ◽  
Extensive Field ◽  
Stream Hydraulics ◽  
Continue Research ◽  
Lake Drainage ◽  
Ice Water

Abstract. The glacier-dammed Lac des Faverges, located on Glacier de la Plaine Morte (Swiss Alps), has drained annually as a glacier lake outburst flood since 2011. In 2018, the lake volume reached more than 2 × 106 m3, and the resulting flood caused damage to the infrastructure downstream. In 2019, a supraglacial channel was dug to artificially initiate a surface lake drainage, thus limiting the lake water volume and the corresponding hazard. The peak in lake discharge was successfully reduced by over 90 % compared to 2018. We conducted extensive field measurements of the lake-channel system during the 48 d drainage event of 2019 to characterize its hydraulics and thermodynamics. The derived Darcy–Weisbach friction factor, which characterizes the water flow resistance in the channel, ranges from 0.17 to 0.48. This broad range emphasizes the factor's variability and questions the choice of a constant friction factor in glacio-hydrological models. For the Nusselt number, which relates the channel-wall melt to the water temperature, we show that the classic, empirical Dittus–Boelter equation with the standard coefficients does not adequately represent our measurements, and we propose a suitable pair of coefficients to fit our observations. This hints at the need to continue research into how heat transfer at the ice–water interface is described in the context of glacial hydraulics.

scholarly journals Drainage of an ice-dammed lake through a supraglacial stream: hydraulics and thermodynamics

2021 ◽  
Author(s):  
Christophe Ogier ◽  
Mauro A. Werder ◽  
Matthias Huss ◽  
Isabelle Kull ◽  
David Hodel ◽  
...  
Keyword(s):  
Friction Factor ◽  
Field Measurements ◽  
Swiss Alps ◽  
Water Volume ◽  
Lake Volume ◽  
Constant Friction ◽  
Extensive Field ◽  
Stream Hydraulics ◽  
Lake Drainage ◽  
Ice Water

Abstract. The glacier-dammed Lac des Faverges, located on Glacier de la Plaine Morte (Swiss Alps), drained annually as a glacier lake outburst flood since 2011. In 2018, the lake volume reached more than 2 × 106 m3 and the resulting flood caused damages to the infrastructure downstream. In 2019, a supraglacial channel was dug to artificially initiate a surface lake drainage, thus limiting the lake water volume and the corresponding hazard. The peak in lake discharge was successfully reduced by over 90 % compared to 2018. We conducted extensive field measurements of the lake-channel system during the 48-days drainage event of 2019 to characterize its hydraulics and thermodynamics. The derived Darcy-Weisbach friction factor, which characterizes the water flow resistance in the channel, ranges from 0.17 to 0.48. This broad range emphasizes the factor’s variability, and questions the choice of a constant friction factor in glacio-hydrological models. For the Nusselt number, which relates the channel-wall melt to the water temperature, we show that the classic, empirical Dittus-Boelter equation with the standard coefficients is not adequately representing our measurements, and we propose a suitable pair of coefficients to fit our observations. This hints at the need to continue the research into how heat transfer at the ice/water interface is described in the context of glacial hydraulics.

SEDIMENT BALANCE OF THE VISTULA LAGOON

2017 ◽  
Author(s):  
Vladimir Chechko ◽  
Vladimir Chechko ◽  
Boris Chubarenko ◽  
Boris Chubarenko
Keyword(s):  
Baltic Sea ◽  
Field Measurements ◽  
Water Volume ◽  
Critical Element ◽  
Vistula Lagoon ◽  
The Baltic Sea ◽  
Direct Measurements ◽  
Biogenic Components ◽  
The Baltic ◽  
The Vistula Lagoon

Vistula Lagoon is the second largest lagoon in the Baltic Sea with maximum depth 5.2 m and average depth 2.7 m. Water volume and area are 2.3 km3 and 838 km2. Lagoon is connected with the Baltic Sea by single inlet 400 m wide and 10-12 m deep. Sediment budget estimation were made using literature sources, results of field measurements (hydrology, suspended sediment content, upper layer sediment structure, direct measurements of sedimentation in summer and winter conditions). The budget for terrigene and biogenic components of sediments were made, considering their contributions from the rivers, inflow from the Baltic Sea, coastal erosion and aerial flux, biological production within the lagoon, totally - ca. 730 thousands ton per year. Nearly half of total gain is washed out (105 and 244 thousands ton per year of terrigene and biogenic components), another half is dissolved and mineralized (biogenic component), and only 10% is deposited on the bottom, resulting in rather low sedimentation rate - 0.4 mm/year during last 100 years. Paper explain the reason of difference with estimation made in (Chubarenko&Chubarenko, 2002) and concludes that the clarification of estimates of the amounts of sediments transported from the lagoon to the Baltic Sea is a critical element for understanding the evolution of the Vistula Lagoon as a sedimentation system.

scholarly journals Modeling Antarctic subglacial lake filling and drainage cycles

2016 ◽  
Vol 10 (4) ◽  
pp. 1381-1393 ◽  
Author(s):  
Christine F. Dow ◽  
Mauro A. Werder ◽  
Sophie Nowicki ◽  
Ryan T. Walker
Keyword(s):  
Internal Controls ◽  
Water Volume ◽  
Lake Basin ◽  
Subglacial Lake ◽  
Subglacial Environment ◽  
Ice Surface ◽  
Ice Stream ◽  
Slow Moving ◽  
Lake Drainage ◽  
Subglacial Lakes

Abstract. The growth and drainage of active subglacial lakes in Antarctica has previously been inferred from analysis of ice surface altimetry data. We use a subglacial hydrology model applied to a synthetic Antarctic ice stream to examine internal controls on the filling and drainage of subglacial lakes. Our model outputs suggest that the highly constricted subglacial environment of our idealized ice stream, combined with relatively high rates of water flow funneled from a large catchment, can combine to create a system exhibiting slow-moving pressure waves. Over a period of years, the accumulation of water in the ice stream onset region results in a buildup of pressure creating temporary channels, which then evacuate the excess water. This increased flux of water beneath the ice stream drives lake growth. As the water body builds up, it steepens the hydraulic gradient out of the overdeepened lake basin and allows greater flux. Eventually this flux is large enough to melt channels that cause the lake to drain. Lake drainage also depends on the internal hydrological development in the wider system and therefore does not directly correspond to a particular water volume or depth. This creates a highly temporally and spatially variable system, which is of interest for assessing the importance of subglacial lakes in ice stream hydrology and dynamics.

scholarly journals Remote sounding of Greenland supraglacial melt lakes: implications for subglacial hydraulics

2007 ◽  
Vol 53 (181) ◽  
pp. 257-265 ◽  
Author(s):  
Jason E. Box ◽  
Kathleen Ski
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Lake Depth ◽  
Cross Sectional ◽  
Overburden Pressure ◽  
Ice Dynamics ◽  
Subglacial Environment ◽  
Lake Volume ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Lake Drainage

AbstractA supraglacial lake-depth retrieval function is developed, based on the correspondence between moderate-resolution imaging spectroradiometer (MODIS) reflectance and water depth measured during raft surveys. Individual lake depth, area and volume statistics, including short-term temporal changes for Greenland’s southwestern ablation region, were compiled for 2000–05. The maximum area of an individual lake was found to be 8.9 km2, the maximum volume 53.0 × 106 m3 and the maximum depth 12.2 m, sampling over 0.0625 km2 pixel areas. The total lake volume reaches >1 km3 in this region by July each year. The importance of melt lake reservoirs to Greenland ice-sheet flow may be a feedback between abrupt lake drainage events and ice dynamics. Lake-outburst volumes up to 31.5 × 106 m3 d−1 are capable of providing sufficient water via moulins to hydraulically pressurize the subglacial environment. Since the overburden pressure at the base of a flooded moulin is greater than that provided by ice, lake-outburst events seem capable of exerting sufficient upward force to lift the ice sheet locally, if water flow in the subglacial environment is constrained laterally. Considering a moulin with a 10 m2 cross-sectional area, basal pressurization can be maintained over lake-outburst episodes lasting hours to days.

Valuation of growing stock using multisource GIS data, a stem quality database, and bucking simulation

2018 ◽  
Vol 48 (8) ◽  
pp. 888-897 ◽  
Author(s):  
Blanca Sanz ◽  
Jukka Malinen ◽  
Vesa Leppänen ◽  
Rubén Valbuena ◽  
Tuomo Kauranne ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Field Measurements ◽  
Product Yield ◽  
Optimization Methods ◽  
Raw Material ◽  
Diameter Distribution ◽  
Target Area ◽  
Product Price ◽  
Extensive Field ◽  
Stem Quality

Customer-oriented production as a sawmill strategy requires up-to-date information on the available raw material resources. Bucking is a process in which the tree stem is divided into products based on the roundwood user’s needs regarding products and their quality and dimensions. Optimization methods are employed in bucking to recover the highest value of the stem for a given product price matrix and requested length–diameter distribution. A method is presented here for assessing the value of harvestable timber stands based on their product yield. Airborne laser scanning, multispectral imagery, and field plots were used to produce timber statistics for a grid covering the target area. The statistics for the plots were generated from this grid. The value of the estimated tree list was assessed using a bucking-to-value simulator together with a stem quality database. Different product yield simulations in terms of volumes, timber assortment recoveries, wood paying capabilities (WPC) and value estimations based on the presented method, and extensive field measurements were compared. As a conclusion, this method can estimate WPC for pulpwood and sawlogs with root mean squared errors of 32.7% and 38.5%, respectively, relative to extensive field measurements.

scholarly journals Filling and drainage of a subglacial lake beneath the Flade Isblink ice cap, northeast Greenland

2022 ◽  
Author(s):  
Qi Liang ◽  
Wanxin Xiao ◽  
Ian Howat ◽  
Xiao Cheng ◽  
Fengming Hui ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Aquifer Storage ◽  
Subglacial Lake ◽  
Ice Cap ◽  
Lake Volume ◽  
Basin Surface ◽  
Multi Temporal ◽  
Lake Drainage ◽  
Subglacial Lakes

Abstract. The generation, transport, storage and drainage of meltwater beneath the ice sheet play important roles in the Greenland ice sheet (GrIS) system. Active subglacial lakes, common features in Antarctica, have recently been detected beneath GrIS and may impact ice sheet hydrology. Despite their potential importance, few repeat subglacial lake filling and drainage events have been identified under Greenland Ice Sheet. Here we examine the surface elevation change of a collapse basin at the Flade Isblink ice cap, northeast Greenland, which formed due to sudden subglacial lake drainage in 2011. We estimate the subglacial lake volume evolution using multi-temporal ArcticDEM data and ICESat-2 altimetry data acquired between 2012 and 2021. Our long-term observations show that the subglacial lake was continuously filled by surface meltwater, with basin surface rising by up to 55 m during 2012–2021 and we estimate 138.2 × 106 m3 of meltwater was transported into the subglacial lake between 2012 and 2017. A second rapid drainage event occurred in late August 2019, which induced an abrupt ice dynamic response. Comparison between the two drainage events shows that the 2019 drainage released much less water than the 2011 event. We conclude that multiple factors, e.g., the volume of water stored in the subglacial lake and bedrock relief, regulate the episodic filling and drainage of the lake. By comparing the surface meltwater production and the subglacial lake volume change, we find only ~64 % of the surface meltwater successfully descended to the bed, suggesting potential processes such as meltwater refreezing and firn aquifer storage, need to be further quantified.

The development of a subglacial lake monitored with radio echo sounding and comparison with water volumes released during jökulhlaups: Case study from the Eastern Skaftá Cauldron in the Vatnajökull ice cap, Iceland

2020 ◽  
Author(s):  
Eyjolfur Magnusson ◽  
Finnur Pálsson ◽  
Magnús T. Gudmundsson ◽  
Thórdís Högnadóttir ◽  
Christian Rossi ◽  
...  
Keyword(s):  
Minimum Size ◽  
Water Volume ◽  
Potential Hazard ◽  
Volume Estimate ◽  
Lake Volume ◽  
Geothermal Activity ◽  
Before And After ◽  
Radio Echo Sounding ◽  
Water Volumes ◽  
Echo Sounding

<p>We present a 6 year record of repeated radio echo sounding (RES) on a profile grid (200-400 m between profiles) surveyed over the Eastern Skaftá Cauldron (ESC). ESC is an ice cauldron produced and maintained by powerful geothermal activity (~1 GW) at the glacier bed. Beneath the cauldron and 200-400 m of ice, water accumulates in a lake and is regularly released in jökulhlaups. The maximum discharge in the river Skaftá exceeded 3000 m<sup>3</sup> s<sup>-1</sup> in the most recent ones in 2015 and 2018. The record starts in 2014 and consists of annual measurements, obtained in June each year; the last on June 2019. Comparison of the repeated RES profiles (2D migrated) reveals the margin of the lake at different times and enables a classifying of traced reflections into lake and bedrock measurements. The bedrock measurements were obtained with the lake close to its minimum size in 2016, 2017 and 2019 (£~1 km<sup>2</sup> compared to 4.0 km<sup>2</sup> in 2015), hence it is possible to obtain fairly accurate digital elevation model (DEM) of the glacier/lake bed. This DEM is further constrained by two borehole measurements of the lake bed elevation at its centre. The traced lake reflections and comparison with the bedrock DEM enables creation of a lake thickness maps and an estimate of the lake volume for each survey. The lake thickness maps and volumes in June 2015 and 2018 are compared with the surface lowering pattern and water volumes drained in the jökulhlaups in October 2015 and August 2018. The drained water volume was derived by integrating the surface lowering during the jökulhlaups and adding estimated volume of crevasses formed in the events. The lowering in the 2015 jökulhlaup was obtained from TanDEM-X DEMs of September 23<sup>rd</sup> and October 10<sup>th</sup>, shortly before and after the jökulhlaup. The lowering in the 2018 jökulhlaup was derived from dense set of airborne altimetry profiles acquired on August 9<sup>th</sup>, a few days after the jökulhlaup, compared with a DEM in June 2018 (ArcticDEM in July 2017 corrected with dense GNSS profiles in June 2018). The lake volume estimate from the RES data is 240x10<sup>6</sup> m<sup>3</sup> in June 2015 but 320±20x10<sup>6</sup> m<sup>3</sup> drained from the cauldron in October. In June 2018 a relatively dense RES profile grid (~200 m between profiles) reveals a lake volume of 180x10<sup>6</sup> m<sup>3</sup> while 210±30x10<sup>6</sup> m<sup>3</sup> drained from the cauldron in August. This comparison demonstrates the applicability of our survey approach to monitor the water accumulation in the lake and thus better constrain potential hazard in jökulhlaups.</p>

Self‐potentials associated with the Yanacocha high‐sulfidation gold deposit in Peru

Geophysics ◽  
2002 ◽  
Vol 67 (3) ◽  
pp. 684-689 ◽  
Author(s):  
Mark Goldie
Keyword(s):  
Apparent Resistivity ◽  
Direct Relationship ◽  
Field Measurements ◽  
Gold Deposits ◽  
Mineral Deposits ◽  
Silica Body ◽  
High Sulfidation ◽  
Extensive Field ◽  
Self Potential ◽  
Peak Value

Significant self‐potential (SP) anomalies characterize the large silica bodies associated with high‐sulfidation oxide gold deposits in the Yanacocha district, Peru. Large SP effects and high apparent resistivities have been observed that coincide with areas of intense silicification. Negative SP anomalies of several volts have been routinely recorded on numerous projects and deposits. The peak value measured was −10.2 V. A direct relationship is shown to exist between the magnitude of an SP response and the size and apparent resistivity of a silica body. Extensive field measurements over numerous high‐sulfidation deposits show that the negative SP effect increases with the size and/or resistivity contrast associated with these unique mineral deposits.

scholarly journals Recent glacier and lake changes in High Mountain Asia and their relation to precipitation changes

2019 ◽  
Vol 13 (11) ◽  
pp. 2977-3005 ◽  
Author(s):  
Désirée Treichler ◽  
Andreas Kääb ◽  
Nadine Salzmann ◽  
Chong-Yu Xu
Keyword(s):  
Shuttle Radar Topography Mission ◽  
Reanalysis Data ◽  
Tien Shan ◽  
Water Volume ◽  
High Mountain ◽  
The Tibetan Plateau ◽  
Glacier Surface ◽  
Spatially Resolved ◽  
Lake Volume ◽  
Precipitation Increase

Abstract. We present an updated, spatially resolved estimate of 2003–2008 glacier surface elevation changes for the entire region of High Mountain Asia (HMA) from ICESat laser altimetry data. The results reveal a diverse pattern that is caused by spatially greatly varying glacier sensitivity, in particular to precipitation availability and changes. We introduce a spatially resolved zonation where ICESat samples are grouped into units of similar glacier behaviour, glacier type and topographic settings. In several regions, our new zonation reveals local differences and anomalies that have not been described previously. Glaciers in the Eastern Pamirs, Kunlun Shan and central TP were thickening by 0.1–0.7 m a−1, and the thickening anomaly has a crisp boundary in the Eastern Pamirs that continues just north of the central Karakoram. Glaciers in the south and east of the TP were thinning, with increasing rates towards southeast. We attribute the glacier thickening signal to a stepwise increase in precipitation around ∼1997–2000 on the Tibetan Plateau (TP). The precipitation change is reflected by growth of endorheic lakes in particular in the northern and eastern TP. We estimate lake volume changes through a combination of repeat lake extents from Landsat data and shoreline elevations from ICESat and the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) for over 1300 lakes. The rise in water volume contained in the lakes corresponds to 4–25 mm a−1, when distributed over entire catchments, for the areas where we see glacier thickening. The precipitation increase is also visible in sparse in situ measurements and MERRA-2 climate reanalysis data but less visible in ERA-Interim reanalysis data. Taking into account evaporation loss, the difference between average annual precipitation during the 1990s and 2000s suggested by these datasets is 34–100 mm a−1, depending on region, which can fully explain both lake growth and glacier thickening (Kunlun Shan) or glacier geometry changes such as thinning tongues while upper glacier areas were thickening or stable (eastern TP). The precipitation increase reflected in these glacier changes possibly extended to the northern slopes of the Tarim Basin, where glaciers were nearly in balance in 2003–2008. Along the entire Himalaya, glaciers on the first orographic ridge, which are exposed to abundant precipitation, were thinning less than glaciers in the dryer climate of the inner ranges. Thinning rates in the Tien Shan vary spatially but are rather stronger than in other parts of HMA.

Soil factors improve predictions of plant species distribution in a mountain environment

2017 ◽  
Vol 41 (6) ◽  
pp. 703-722 ◽  
Author(s):  
Aline Buri ◽  
Carmen Cianfrani ◽  
Eric Pinto-Figueroa ◽  
Erika Yashiro ◽  
Jorge E Spangenberg ◽  
...  
Keyword(s):  
Plant Species ◽  
Soil Ph ◽  
Species Distribution ◽  
Predictive Power ◽  
Species Distributions ◽  
Field Measurements ◽  
Swiss Alps ◽  
Climatic Variables ◽  
Soil Parameters ◽  
Soil Factors

Explanatory studies suggest that using very high resolution (VHR, 1–5 m resolution) topo-climatic predictors may improve the predictive power of plant species distribution models (SDMs). However, the use of VHR topo-climatic data alone was recently shown not to significantly improve SDM predictions. This suggests that new ecologically-meaningful VHR variables based on more direct field measurements are needed, especially since non topo-climatic variables, such as soil parameters, are important for plants. In this study, we investigated the effects of adding mapped VHR predictors at a 5 m resolution, including field measurements of temperature, carbon isotope composition of soil organic matter (δ13CSOM values) and soil pH, to topo-climatic predictors in SDMs for the Swiss Alps. We used data from field temperature loggers to construct temperature maps, and we modelled the geographic variation in δ13CSOM and soil pH values. We then tested the effect of adding these VHR mapped variables as predictors into 154 plant SDMs and assessed the improvement in spatial predictions across the study area. Our results demonstrate that the use of VHR predictors based on more proximal field measurements, particularly soil parameters, can significantly increase the predictive power of models. Predicted soil pH was the second most important predictor after temperature, and predicted δ13CSOM was fourth. The greatest increase in model performance was for species found at high elevation (i.e. 1500–2000 m a.s.l.). Addition of predicted soil factors thus allowed better capturing of plant requirements in our models, showing that these can explain species distributions in ways complementary to topo-climatic variables. Modelling techniques to generalize edaphic information in space and then predict plant species distributions revealed a great potential in complex landscapes such as the mountain region considered in this study.

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