“Glacier hydrology is the study of water storage and transport in glaciers – and how glaciers release this water to river systems” [Cuffey and Paterson, 2010]

Drainage density very high, dendritic network, lack well developed trunk systems

Wet subglacial environments important for dissolution due to abundance of freshly crushed rock material.

Finite amount of dissolved material it is the dilution effect as discharge changes – extreme melt during summer is usually supraglacial and will dilute dissolved load which has a high electrical conductivity

Not a linear relationship between flowrate/discharge and sediment load

Rising stage can carry more sediment and the falling stage is ‘exhausted’ and cant carry as much (Hysteresis loop)

Measured using an automatic vaccum sampler or turbidity meters

Major source of sediment to North Atlantic via fluvial & aeolian inputs

Progressive change of the outlet as the glacier retreats and the glacier gets further away from the outwash.

Holocene was when the growth of it happened with 5 major glofs per century (Guðmundsson et al., 2003)

Johulhaulps occur on a roughly decadal scale (Bjornsson, 1997)

(6) Localised massive, matrix-supported diamicton units and deformed bedding containing rip-up clasts (Types G and H), in Types II and III, and Type III, outwash, respectively.

1. sediment derived from glacial erosion and subglacial sediment storage

2. debris produced by the weathering and instability of deglaciated bedrock

3. glacigenic debris covering hillslopes or accumu-lated in depositional landforms such as lateral and terminal moraines. Storage landforms derived from the re-working of other sediment sources, such as debris cones or fluvial terraces, can act as sediment sources themselves.

IPCC stated that longer summers produce more meltwater and runoff.

Type I sandurs are 'classic' sandurs, defined as those which are mainly produced by 'normal', ablation-related seasonal meltwater flows, commonly operating within a braided river environment, with no exceptional inputs of sediment, and with regular reworking of proglacial channel sediments.

Type II outwash is dominated by jokulhlaup drainage from ice-dammed or subglacial lakes, i.e. by 'limnoglacial' floods. These sandurs are characterised by large-scale, coarse-grained bedforms.

Type III outwash is dominated by 'volcano-glacial' jokulhlaup drainage, such as that which affects large areas of the Icelandic sandurs

Sediment inputs to proglacial environments are largely derived from the glacier source generated both by glacial and fluvioglacial transport to the ice marginal zone

It has been proposed that where jökulhlaups occur they play a dominant role in the evolution of proglacial outwash plains. However, extraordinary meltwater and sediment discharge associated with glacier surging can also play a crucial role in the proglacial system. The interplay of surge-related and jökulhlaup floods has been investigated at Skeiðarárjökull (Russell et al., 2001)

The issue of magnitude and frequency in fluvial geomorphology has been a persistent
problem for many years.

High frequency, low magnitude events such as rainstorms can have a significant impact on small basins (Warburton, 1994).

diurnal variations are controlled by daily temperature changes. Diurnal variations are more marked in alpine than Arctic glacial drainage basins and small glacierized basins display larger diurnal variations than large basins.

Winter low flow is followed by spring melt seasons, into a peak melt in summer.

Discharge is controlled by glacier size eg. in glacial advances discharge increases but can also increase if there is rapid melting/retreat.

High magnitude, low frequency events eg. Jokulhlaups have high amounts of energy, allowing them to do more 'work' such as sediment movement, erosion and reowrking.

Maizels (1983) stated that areas experiencing long- term deglaciation had rivers in transition from predominantly braided, high gradient, low-sinuosity channels to single-thread, low-gradient deeper, more sinuous channels. Due to glacial meltwater discharge and a continuing sediment input by the glacier, proglacial systems (under equilibrium conditions?) are aggrading systems on the long term, experiencing cycles of aggradation and degradation. Incision and degradation are expected to dominate during and after deglaciation, re- spectively (Gurnell et al., 1999)

proximity to a glacier as a main source of meltwater implies a high temporal variability of discharge on multiple scales (Marren, 2005)

Daily and seasonal periodicity is complemented by floods caused by meteorolog- ical conditions (e.g. temperature and precipitation), and exceptional glacier dynamics (e.g. Baewert and Morche, 2014). This variability is associated with a variability in sediment supply from different sources (glacier, sediment stores within the proglacial area) to the proglacial channel network (Leggat et al., 2015).

sediment-transporting flows are frequent during the summer months and highly predictable, being mostly linked to air temperature dynamics rather than to intense precipitation events (Mao et al. 2014)

In non-glacial rivers, the direction and magnitude of hysteretic loops have been mostly related to the activity and proximity of sediment sources. In particular, clockwise and counter-clockwise hystereses have been attributed to unlimited and limited sediment supply, respectively. Clockwise hysteresis has been associated with early exhaustion of sediment sources and closeness of the main sources of sediments

In proglacial rivers, the positive relationship between bedload transport rate and water discharge (and thus shear stress and stream power) seems to be weaker, with much larger data scatter, than in non-glacierized systems.

Sediment yield tends to increase with basin size, and the erosion rates increase from small cirque glaciers to large, fast moving glaciers.