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Glacial geology
Published in Barry G. Clarke, Engineering of Glacial Deposits, 2017
Meltwater emerging from a glacier carries debris to form outwash fans, kames and kame terraces. The debris spreads out in front of the ice margin and backs over the ice; therefore, the topology of the glaciofluvial landforms depends on their location with respect to the ice margin, the presence of buried ice and the amount of transported sediment. Braided river systems develop downstream of the ice margin creating an outwash fan as the glacial debris is deposited (Figure 2.29). While these river systems form at the ice margins, they can contain buried ice, which on melting leads to kettle holes, water-filled pits that are gradually filled with further glacial debris possibly leading to conical lenses of distinctly different materials from the surrounding outwash fan. If the outwash fan crosses an extensive area of ice as the ice melts, it creates a hummocky surface to the rear of the outwash fan known as kame and kettle (hollows) topography. Kames, consisting of well-sorted deposits of sand and gravel, are formed at the ice margin creating either isolated hummocks or broad flat-elevated areas (Figure 2.30). The velocity of meltwater reduces rapidly as it emerges from a glacier resulting in coarser materials being deposited near to the outlet and finer material being carried further afield (cf. pipe discharge into a lagoon). As the ice retreats, the meltwater may be diverted along the ice margin creating a kame terrace. Kames can vary from a few hundred metres to over a kilometre in length. Kame terraces form parallel to the direction of ice flow from streams running along the sides of a glacier.
Mass Balance and Meteorological Conditions at Universidad Glacier, Central Chile
Published in Diego A. Rivera, Alex Godoy-Faundez, Mario Lillo-Saavedra, Andean Hydrology, 2018
Christophe Kinnard, Shelley MacDonell, Michal Petlicki, Carlos Mendoza Martinez, Jakob Abermann, Roberto Urrutia
Mass balance on mountain glaciers typically displays a strong relationship with altitude. The mass balance gradient is the rate of change of mass balance with altitude (db/dz in mm w.e. m1); it drives the ice flow from the accumulation to the ablation zone. Its value near the Equilibrium Line Altitude (ELA) is called the activity index (Lliboutry, 1964) and is positively related with the ice turnover rate of the glacier. The mass balance gradient is typically greater in the ablation zone (10 to 20 mm m−1) where it depends primarily on temperature-related ablation processes, but reduces in the glacier accumulation zone where it depends primarily on accumulation processes (Francou and Pouyaud, 2004).
Landslide Hazards and cLimate Change: A Perspective from the United States
Published in Ken Ho, Suzanne Lacasse, Luciano Picarelli, Slope Safety Preparedness for Impact of Climate Change, 2017
Sea level has risen since the 1960s due to melting of land ice and from the thermal expansion of water due to rising temperatures (Bindoff et al., 2007). Tide gage data indicate that the global average rate of mean sea level rise between 1961 and 2003 was 1.8 ± 0.5 mm/yr (Solomon et al., 2007). Meehl et al. (2007) projected a range in total sea level rise from 0.18 to 0.59 m by the 2090–2099 period (relative to 1980–1999), but could not confidently account for the impact of dynamic changes in ice flow from Greenland and Antarctica. Pfeffer et al. (2008) accounted for ice dynamics and concluded that a sea-level rise of 0.8 m by 2100 was most likely, with a maximum rise of 2 m physically possible.
Effects of climate change on river-ice processes and ice jams
Published in International Journal of River Basin Management, 2023
B. C. Burrell, S. Beltaos, B. Turcotte
As the surface concentration of frazil pans or slush increases, congestion may occur, at a channel or border-ice constriction, a tight bend, or at a channel segment characterized by slow surface velocities. Once ice bridging occurs, incoming ice floes may accumulate edge to edge and extend upstream. However, where flow velocities are in excess of ∼0.7 m/s (Prowse, 1995) and for a Froude number greater than ∼0.1, surface ice floes coming into the ice front may be carried under it and deposited on the underside of the ice cover downstream, thereby hydraulically thickening the ice cover and reducing flow velocities upstream. As the ice front progresses upstream, either by surface juxtaposition or by hydraulic thickening, near-surface interstitial water freezes; as a result, the accumulation gains internal strength and can resist the driving forces of the cover’s downslope weight and under-ice flow drag (Beltaos, 2013).
Antarctic-wide annual ice flow maps from Landsat 8 imagery between 2013 and 2019
Published in International Journal of Digital Earth, 2021
Qiang Shen, Hansheng Wang, C. K. Shum, Liming Jiang, Houtse Hsu, Fan Gao, Yingli Zhao
The thawing of many glaciers along the peripheral of Antarctic ice sheet is accelerating, which is contributing to accelerated sea level rise resulting from climate change (Thomas et al. 2004; Eric Chen et al. 2009; Shepherd et al. 2012; Gardner et al. 2018; Shen et al. 2018; Rignot et al. 2019). Tracking the ongoing behavior of the Antarctic ice sheet is crucial for the accurate prediction of global sea level rise, which requires an enhanced and thorough continent-wide investigation of Antarctic ice dynamics. Ice flow velocity is an important glaciological parameter to determine ice dynamics, including the ice sheet mass balance, its thickness changes, the peripheral glacier discharge rate and its link to ice flow instability.