Glacier Drainage Basin Research Articles

A data set of monthly freshwater fluxes from the Greenland ice sheet’s marine-terminating glaciers on a glacier–basin scale 2010–2020

The loss of mass from the Greenland ice sheet causes an increasing influx of freshwater to the Greenlandic fjords and the oceans. Freshwater fluxes from marine-terminating glaciers are important to understand fjord circulation and ecosystem dynamics. Here, we present a data set constructed by reformulating existing products into a shared temporal and spatial framework. We combine three publicly available data sets of solid-ice discharge (iceberg), liquid-surface runoff (runoff) and basal melt to present a cohesive overview of the flow of freshwater from marine-terminating glaciers to the Greenlandic fjords. We also calculate glacier drainage basins and compare our findings to previous studies showing that drainage-basin sizes may vary considerably depending on how they were reconstructed. The data set will be a valuable asset to oceanographic, glaciological and marine biological research activities.

Estimation of surface melt induced melt pond depths over Amery Ice Shelf, East Antarctica using Multispectral and ICESat-2 data

Surface melting is increasing over the Antarctica continent, with unknown impacts on glacier and ice sheet dynamics at the ice-bed interface. Surface meltwater drains to the bed of Antarctica ice sheets and outlet glaciers, causing accelerations in ice flow (up to 100% greater than the annual mean). Because melt occurrences are currently erratic (also Antarctica surface melt refreezes), effective subglacial drainage cannot be maintained, resulting in repeated short-lived ice flow disturbances and calving of ice shelves. Longterm exposure to strong surface melting promotes the formation of melt ponds and subsequently Supraglacial lakes and therefore there is possibility of hydrofracturing. The present study aims to estimate the volume of surface melt-induced melt ponds over the Amery Ice Shelf (AIS) using a physically-based radiative transfer model. The AIS, located on Antarctica's east coast, is one of the world's biggest glacier drainage basins. The ICESat-2 geolocated photon data were used to validate the depth estimates of melt ponds derived from Landsat-8 and Sentinel-2 multispectral datasets based on the model. The average depth estimated is around 1.9±0.6 m for the melt ponds adopted for the present study. The present study aims to quantify surface melt over the Antarctica continent (AIS region) in the context of India’s scientific credentials in polar science. We recommend monitoring extensive surface melt and subsurface refreezing which might result in more ponding above impermeable ice layers in the coming years.

Water stable isotopes in snow along a traverse of the West Antarctic Ice Sheet: insights into moisture origins, air-masses distillation history, and climatic value.

This study investigated the water isotopic content (δ18O, δD, d-excess) of the surface snow along a 995 km traverse over the West Antarctic Ice Sheet from the Möller Ice Stream - Institute Ice Stream to the upper reaches of the Pine Island Glacier drainage basin. The purpose of this study was to evaluate the climatic record preserved in the snow. We analyzed 92 surface samples (~0.15-0.20 m deep), retrieved during 2014/2015 austral summer from every ~10 km along the traverse route, using the laser spectroscopy technique. We computed the isotopic-geographical characteristics and spatial co-isotopic empirical relationships and compared the isotopic results with the tropospheric mean annual temperature and air mass trajectories. Our isotopic results were sensitive to capturing the well-known climatic asymmetry between the Amundsen-Bellingshausen Sea (ABS; which receives more influence from warmer (oceanic) air masses) and Weddell Sea (WS; more influenced by colder (continental) air masses) sectors. Further, the spatial distribution of δs and d-excess and the co-isotopic relationships reflect two preferential fractionation paths: one from the coast of the ABS sector to the WS sector, and another from the coast of the WS sector to the inland. The Pacific Ocean is confirmed as the primary source of moisture.

Drainage basin delineation for outlet glaciers of Northeast Greenland based on Sentinel-1 ice velocities and TanDEM-X elevations

The drainage divides of ice sheets separate the overall glaciated area into multiple sectors. These drainage basins are essential for partitioning mass changes of the ice sheet, as they specify the area over which basin specific measurements are integrated. The delineation of drainage basins on ice sheets is challenging due to their gentle slopes accompanied by local terrain disturbances and complex patterns of ice movement. Until now, in Greenland the basins have been mostly delineated along the major ice divides, which results in large drainage sectors containing multiple outlet glaciers. However, when focusing on measuring glaciological parameters of individual outlet glaciers, more detailed drainage basin delineations are needed. Here we present for the first time a detailed and fully traceable approach that combines ice sheet wide velocity measurements by Sentinel-1 and the high resolution TanDEM-X global DEM to derive individual glacier drainage basins. We delineated catchments for the Northeast Greenland Ice Sheet with a modified watershed algorithm and present results for 31 drainage basins. Even though validation of drainage basins remains a difficult task, we estimated basin probabilities from Monte-Carlo experiments and applied the method to a variety of different ice velocity and DEM datasets finding discrepancies of up to 16% in the extent of catchment areas. The proposed approach has the potential to produce drainage areas for the entirety of the Greenland and Antarctic ice sheets.

Global-scale hydrological response to future glacier mass loss

Worldwide glacier retreat and associated future runoff changes raise major concerns over the sustainability of global water resources1–4, but global-scale assessments of glacier decline and the resulting hydrological consequences are scarce5,6. Here we compute global glacier runoff changes for 56 large-scale glacierized drainage basins to 2100 and analyse the glacial impact on streamflow. In roughly half of the investigated basins, the modelled annual glacier runoff continues to rise until a maximum (‘peak water’) is reached, beyond which runoff steadily declines. In the remaining basins, this tipping point has already been passed. Peak water occurs later in basins with larger glaciers and higher ice-cover fractions. Typically, future glacier runoff increases in early summer but decreases in late summer. Although most of the 56 basins have less than 2% ice coverage, by 2100 one-third of them might experience runoff decreases greater than 10% due to glacier mass loss in at least one month of the melt season, with the largest reductions in central Asia and the Andes. We conclude that, even in large-scale basins with minimal ice-cover fraction, the downstream hydrological effects of continued glacier wastage can be substantial, but the magnitudes vary greatly among basins and throughout the melt season.

The modelled surface mass balance of the Antarctic Peninsula at 5.5 km horizontal resolution

Abstract. This study presents a high-resolution (∼ 5.5 km) estimate of surface mass balance (SMB) over the period 1979–2014 for the Antarctic Peninsula (AP), generated by the regional atmospheric climate model RACMO2.3 and a firn densification model (FDM). RACMO2.3 is used to force the FDM, which calculates processes in the snowpack, such as meltwater percolation, refreezing and runoff. We evaluate model output with 132 in situ SMB observations and discharge rates from six glacier drainage basins, and find that the model realistically simulates the strong spatial variability in precipitation, but that significant biases remain as a result of the highly complex topography of the AP. It is also clear that the observations significantly underrepresent the high-accumulation regimes, complicating a full model evaluation. The SMB map reveals large accumulation gradients, with precipitation values above 3000 mm we yr−1 in the western AP (WAP) and below 500 mm we yr−1 in the eastern AP (EAP), not resolved by coarser data sets such as ERA-Interim. The average AP ice-sheet-integrated SMB, including ice shelves (an area of 4.1 × 105 km2), is estimated at 351 Gt yr−1 with an interannual variability of 58 Gt yr−1, which is dominated by precipitation (PR) (365 ± 57 Gt yr−1). The WAP (2.4 × 105 km2) SMB (276 ± 47 Gt yr−1), where PR is large (276 ± 47 Gt yr−1), dominates over the EAP (1.7 × 105 km2) SMB (75 ± 11 Gt yr−1) and PR (84 ± 11 Gt yr−1). Total sublimation is 11 ± 2 Gt yr−1 and meltwater runoff into the ocean is 4 ± 4 Gt yr−1. There are no significant trends in any of the modelled AP SMB components, except for snowmelt that shows a significant decrease over the last 36 years (−0.36 Gt yr−2).

Assessment of suspended sediment concentration and load from a large Himalayan glacier

An assessment of suspended sediment concentration (SSC), load, yield and erosion rate has been undertaken for the Gangotri Glacier drainage basin (nearly 50% glaciated) located in the Garhwal Himalayas. Data were collected for four ablation seasons (2008–2011). Mean monthly SSCs, for May, June, July, August and September during the study period was 1,011, 1,384, 1,916, 1,675 and 567 ppm, respectively, indicating highest SSC in July, followed by August. For the entire melt season, the mean daily SSC was computed to be 1,320 ppm. Similar trends were also found for the sediment load and about 67% of the total suspended sediment load of the melt period was transported during the months of July and August. Sediment yield for the study basin was computed to be about 2,863 tonnes km–2yr–1. For the entire ablation period, the erosion from the Gangotri Glacier basin is estimated to be about 1.0 mm. There was a poor relationship between SSC and discharge and hysteresis effect was prominent in the melt stream. The average percentages of clay, silt and sand were found to be 3, 67 and 30%, respectively, which suggest maximum content of silt followed by sand.

Contemporary suspended sediment transfer and accumulation processes in the small proglacial Sætrevatnet sub-catchment, Bødalen, western Norway

A combination of different process monitoring, lake sediment coring and sediment analysis methods and techniques was applied in the 17.5km2 Sætrevatnet sub-catchment in the upper Bødalen drainage basin (Nordfjord, western Norway) in order to define hydro-meteorological controls on runoff, suspended sediment transfer and sediment accumulation, and to determine the role of Lake Sætrevatnet within the drainage basin-wide sediment routing system. The proglacial system shows the typical seasonal and weather-depended runoff variations for glacierized drainage basins. Significant suspended sediment transport is associated to summer glacier melt (when 61.9% of the annual suspended sediment yield was recorded in 2010) as well as to single rainfall events (when 19.8% of the annual suspended sediment yield was recorded in 2010). The intensity of atmospheric energy input and the frequency of heavy rainfall events were found to be critical for the rate of suspended sediment transport within the Sætrevatnet sub-catchment. The computed annual suspended sediment yield from the proglacial area was 24.2tkm−2, which is notably lower as compared with a number of other glacierized basins worldwide. Delta accumulations rates from 2009 (4cmyr−1) and 2010 (3cmyr−1) as well as average annual delta advance ranging from 3.8m to 4.6m confirm the calculated high annual lake sedimentation rate of 1.7cmyr−1. Lake Sætrevatnet (0.02km2) currently traps about 80–85% of the sediments delivered from the upstream-located glacial system highlighting the importance of small ephemeral proglacial lakes within larger valley–fjord sediment routing systems.

The timing and nature of recession of outlet glaciers of Hielo Patagónico Norte, Chile, from their Neoglacial IV (Little Ice Age) maximum positions

The dates of recession of eleven outlet glaciers of the Hielo Patagónico Norte (Northern Patagonian Icefield) from their recent maximum positions have been inferred from dendrochronology, lichenometry, radiocarbon dating and historical sources. We have refined the dating for part of the Little Ice Age period in this area placing a glacial advance to between AD 1650 and 1766 with the latter date favoured as conformable with historical records and an uncalibrated radiocarbon determination. Glacier recession from maximal positions began in the early 1860s–1870s. Recession was largely synchronous on the western and eastern sides of the Icefield. This synchronicity suggests that climate forcing over-rides second-order controls on glacier behaviour such as the nature of the terminal environment (e.g. calving/non-calving) or differences in glacier drainage basin area. We argue that this icefield-wide glacier recession represents a response to post-Little Ice Age warming, and provides further evidence for the global extent and near synchronous termination of the Little Ice Age.

Geological and geomorphological insights into Antarctic ice sheet evolution

Technical advances in the study of ice-free parts of Antarctica can provide quantitative records that are useful for constraining and refining models of ice sheet evolution and behaviour. Such records improve our understanding of system trajectory, influence the questions we ask about system stability and help to define the ice-sheet processes that are relevant on different time-scales. Here, we illustrate the contribution of cosmogenic isotope analysis of exposed bedrock surfaces and marine geophysical surveying to the understanding of Antarctic ice sheet evolution on a range of time-scales. In the Dry Valleys of East Antarctica, 3He dating of subglacial flood deposits that are now exposed on mountain summits provide evidence of an expanded and thicker Mid-Miocene ice sheet. The survival of surface boulders for approximately 14Myr, the oldest yet measured, demonstrates exceptionally low rates of subsequent erosion and points to the persistence and stability of the dry polar desert climate since that time. Increasingly, there are constraints on West Antarctic ice sheet fluctuations during Quaternary glacial cycles. In the Sarnoff Mountains of Marie Byrd Land in West Antarctica, 10Be and 26Al cosmogenic isotope analysis of glacial erratics and bedrock reveal steady thinning of the ice sheet from 10400 years ago to the present, probably as a result of grounding line retreat. In the Antarctic Peninsula, offshore analysis reveals an extensive ice sheet at the last glacial maximum. Based on radiocarbon dating, deglaciation began by 17000cal yr BP and was complete by 9500cal yr BP. Deglaciation of the west and east sides of the Antarctic Peninsula ice sheet occurred at different times and rates, but was largely complete by the Early Holocene. At that time ice shelves were less extensive on the west side of the Antarctic Peninsula than they are today. The message from the past is that individual glacier drainage basins in Antarctica respond in different and distinctive ways to global climate change, depending on the link between regional topography and climate setting.

Geomorphological evidence for variations of the North Patagonian Icefield during the Holocene

Elucidating the timing and extent of former glacier fluctuations is important because of the palaeoclimatic inferences that can be drawn from such studies. Here we present new geomorphological evidence of the patterns of glacier behaviour around the North Patagonian Icefield during the Holocene. Mapping is based on visual interpretation of Landsat 7 ETM+ and Terra ASTER satellite images, including the contemporary glaciers, areas of ice-scoured bedrock, trimlines, glacial lineations, terminal moraines, sandur and fluvial sediments, deltas and ice-contact deposits and alluvial fans. Recession of the icefield is marked by three distinct moraine sets. These moraine sets are interpreted as marking terminal positions related to the “Little Ice Age” and two preceding, but as yet undated, phases of Holocene glacier expansion. Large arcuate terminal moraines in front of three of the western glaciers are interpreted as composite features, reflecting topographic limits to glacier expansion, indicating that caution is required in the interpretation of previous 14C dates obtained from these moraines. There are strong contrasts in the patterns of glacier behaviour between the east and west sides of the North Patagonian Icefield, which cannot be attributed simply to an east/west differential in the rates of change of atmospheric temperature and precipitation. We argue here that glacier response to first-order climate forcing is tempered by second-order controls introduced by regional-scale topographic effects, notably glacier drainage basin extent and area, topographic controls on glacier snout morphology and differences in terminal environment (calving/non-calving) during glacier recession.

Suspended Sediment Transport from the Dokriani Glacier in the Garhwal Himalayas

Estimation of sediment load from glacierized basins is very important for planning, designing, installation and operation of hydro-power projects, including management of reservoirs. In the present study, an assessment of suspended sediment concentration, load, yield and erosion rate has been undertaken for the Dokriani Glacier drainage basin located in the Garhwal Himalayas. About 60% of the total drainage area of this basin is glacierized. Data were collected for four ablation seasons (1995-1998). The mean daily suspended sediment concentrations for June, July, August and September were 452, 933, 965 and 275 mg 1-1, respectively, indicating highest suspended sediment concentration in August, followed by July. Similar trends were also found for the sediment load and about 88% of the total suspended sediment load of the melt period was transported during the months of July and August. Sediment yield for the study basin was computed to be about 2,800 t km-2 yr-1, which is comparable with glacierized basins (10-30% glacierized) in the Pamir region. For the entire ablation period, the erosion from the Dokriani Glacier basin is estimated to be about 1.0 mm. There was a poor relationship between suspended sediment concentration and discharge. The average percentages of clay, silt and sand were found to be 1.4, 67.3 and 31.3%, respectively, which suggest maximum content of silt followed by sand. There was limited variation in the content of clay, silt and sand in the suspended sediment during the ablation period.

Ice velocities of the Lambert Glacier from static GPS observations

Between 1988 and 1995, five seasons of Global Positioning System (GPS) data were collected at seventy-three locations near the 2500 metre contour of the Lambert Glacier Drainage Basin (LGB). These data have been processed using GAMIT/GlobK software to determine surface velocities at the surveyed sites. Results show that velocities along the traverse route vary between 0.5 ma−1 and 63 ma−1 with the location of the major outlet glaciers inside the LGB clearly identifiable within the data. A subset of the LGB GPS data has been studied to investigate an efficient method for determination of ice velocities at remote sites within a single field season. Results from this study have shown that ice velocities within 2% of the long-term estimate may be determined using two to four hour GPS site occupations separated in time by a minimum of forty days.

Morphology and variations of glacial drainage basins in the King George Island ice field, Antarctica

AbstractA Système probatoire pour l’observation de la terre (SPOT) mosaic of King George Island, the largest (1250 Km2) of the South Shetland Islands, West Antarctica, shows its major morphological features. Three main ice domes and 70 glacier drainage basins, covering 92.7% of the King George Island area, strongly controlled by the subglacial morphology and drained by relatively fast-moving tidewater outlet glaciers, were delineated. A general retreat of ice fronts through four decades, more intensely on the eastern side of the island (to the Bransfield Strait), resulted in the loss of about 7% of the glacial cover area. Superficial snow fades were derived from SPOT multispectral imagery and, together with field observations, allowed the transient-snowline elevation to be obtained The latter is estimated to have risen from about 200-250 m in the mid-1950s to 300-350 m by 1988. Spot radio-echo sounding surveys give an overview of the bedrock morphology.

Water flow through temperate glaciers

Understanding water movement through a glacier is fundamental to several critical issues in glaciology, including glacier dynamics, glacier‐induced floods, and the prediction of runoff from glacierized drainage basins. To this end we have synthesized a conceptual model of water movement through a temperate glacier from the surface to the outlet stream. Processes that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology. Where a glacier is covered by a layer of porous, permeable firn (the accumulation zone), the flux of water to the glacier interior varies slowly because the firn temporarily stores water and thereby smooths out variations in the supply rate. In the firn‐free ablation zone, in contrast, the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time. Water moves from the surface to the bed through an upward branching arborescent network consisting of both steeply inclined conduits, formed by the enlargement of intergranular veins, and gently inclined conduits, spawned by water flow along the bottoms of near‐surface fractures (crevasses). Englacial drainage conduits deliver water to the glacier bed at a limited number of points, probably a long distance downglacier of where water enters the glacier. Englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn. Their size adjusts so that they are usually full of water and flow is pressurized. In contrast, water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms; flow is otherwise in an open‐channel configuration. The subglacial drainage system typically consists of several elements that are distinct both morphologically and hydrologically. An upglacier branching, arborescent network of channels incised into the basal ice conveys water rapidly. Much of the water flux to the bed probably enters directly into the arborescent channel network, which covers only a small fraction of the glacier bed. More extensive spatially is a nonarborescent network, which commonly includes cavities (gaps between the glacier sole and bed), channels incised into the bed, and a layer of permeable sediment. The nonarborescent network conveys water slowly and is usually poorly connected to the arborescent system. The arborescent channel network largely collapses during winter but reforms in the spring as the first flush of meltwater to the bed destabilizes the cavities within the nonarborescent network. The volume of water stored by a glacier varies diurnally and seasonally. Small, temperate alpine glaciers seem to attain a maximum seasonal water storage of ∼200 mm of water averaged over the area of the glacier bed, with daily fluctuations of as much as 20–30 mm. The likely storage capacity of subglacial cavities is insufficient to account for estimated stored water volumes, so most water storage may actually occur englacially. Stored water may also be released abruptly and catastrophically in the form of outburst floods.

Late Autumn Runoff and Sediment Transport in a Proglacial Drainage System, Sermilik, East Greenland

Hasholt, Bent: Late Autumn Runoff and Sediment Transport in a Proglacial Drainage System, Sermilik, East Greenland. Geografisk Tidsskrift 93:1–5. Copenhagen 1993. Field investigations of runoff and sediment transport were carried out in the proglacial area of the Mitdluagkat Glacier drainage basin in September 1992. Runoff in the proglacial stream was 32 l/s/km2. Runofffrom the northern flank of the glacier at the outlet of Lake Kugssuag was 14 l/s/km2. Mean daily sediment transport was 17 t/d in the proglacial valley and 0.2 t/d at the outlet of the lake. It was clearly demonstrated that the formation of frazil ice and anchor ice caused increased sediment transport, dominating the total load of the proglacial stream during the measuring period 2/9–19/9.

Numerical estimation of 10000 years later equilibrium ice sheet profile in the Shirase Glacier drainage basin, East Antarctica

Numerical estimation of 10000 years later equilibrium ice sheet profile in the Shirase Glacier drainage basin, East Antarctica

Glacially derived, shallow-marine gold placers of the Cape Yakataga district, Gulf of Alaska

Economic gold-bearing coastal sediment of Holocene age (10 ka) occurs along the Gulf of Alaska coastal margin from Cape Yakataga in the west to Icy Bay in the east, a distance of 50 km. Deposits have been worked since 1898 and total production since then is about 15,000 ounces. Gold is recovered from discontinuous sheets of “ruby” garnet-rich beach sand exposed at low tide along the high-energy storm-dominated coastline. Similar auriferous sand facies are also present within raised marine terraces cut across outwash fans along the narrow mountainous coastal margin. The area has been uplifted by glacio-isostatic rebound following the last glacial maximum and by high-magnitude earthquakes; the area lies along the collision zone between the North American and Pacific plates. Study of uplifted and well-exposed Late Cenozoic strata (the glaciomarine Yakataga Formation) that outcrop along the coastal margin confirms this succession as the source of placer gold. The Yakataga Formation records the rapid accumulation of over 6 km of gold-bearing glaciomarine sediments in a rapidly subsiding forearc basin. These strata have in turn been uplifted as coastal mountains and eroded by glaciers; the White River Glacier and Yakataga Glacier drainage basins can be identified as the principal source of detrital gold along the Yakataga coastline. Auriferous beach sediment is the product of westward reworking of glacial outwash from the White and Yakataga rivers and is accompanied by a well-defined downcurrent reduction in the size and number of gold particles.

Distribution of Reflected Power From the Bed by Radio Echo-Sounding in the Shirase Glacier Drainage Area, East Dronning Maud Land, Antarctica

A large part of the area of the Shirase Glacier drainage basin has been surveyed by airborne (operating frequency: 179 MHz) and ground-based (60 MHz) radio echo-sounding to define the bedrock topography and to investigate the condition of bed/ice interface since 1982.It is shown that the reflection intensity from the bed, which is corrected for attenuation in the ice sheet, has a higher value for reflection intensity in the down-stream area of Shirase Glacier than in the up-stream area. The area of strongest intensity of reflection from the bed coincides with the area for which the calculated temperature at the bed is above −1°C. The boundary area between the highest and lowest values of corrected reflected intensity corresponds to the area of decreasing basal shear stress. It is found that the distribution of high corrected reflection intensity corresponds to the area of thinning of the ice sheet, which has been measured by ice-flow observation in the Shirase Glacier drainage basin.

Distribution of Reflected Power From the Bed by Radio Echo-Sounding in the Shirase Glacier Drainage Area, East Dronning Maud Land, Antarctica

A large part of the area of the Shirase Glacier drainage basin has been surveyed by airborne (operating frequency: 179 MHz) and ground-based (60 MHz) radio echo-sounding to define the bedrock topography and to investigate the condition of bed/ice interface since 1982. It is shown that the reflection intensity from the bed, which is corrected for attenuation in the ice sheet, has a higher value for reflection intensity in the down-stream area of Shirase Glacier than in the up-stream area. The area of strongest intensity of reflection from the bed coincides with the area for which the calculated temperature at the bed is above −1°C. The boundary area between the highest and lowest values of corrected reflected intensity corresponds to the area of decreasing basal shear stress. It is found that the distribution of high corrected reflection intensity corresponds to the area of thinning of the ice sheet, which has been measured by ice-flow observation in the Shirase Glacier drainage basin.