Internal drainage systems of glaciers
Bulat R. Mavlyudov
Institute of geography RAS, Staromonetny per. 29, Moscow 119017 Russia
e-mail: [email protected]
ABSTRACT
It is shown that internal drainage systems (IDS) have an identical structure despite of glaciers sizes and
thermal conditions. IDS channels are formed in glaciers at the temperature of at least -1°С at the bottom. It is
impossible to find the IDS in glaciers of lower ice temperatures. IDS are always developed in channels
originating from: 1) crevasses systems 2) glacier and rock contacts 3) cutting from ice surface. At the base of
intergrain veins in ice IDS channels are not formed. IDS are formed due to gradually increasing systems of
upward channels on a glacier. IDS channels have undergone a quite certain way of evolution that depended
on glacier conditions (glacier mobility, ice thickness and temperatures, formation of crevasses, etc.). IDS
create an opportunity for a prompt transfer of climatic information from the surface of a glacier to its interior.
Owing to the presence of IDS, glaciers react very quickly to (even short-term) climate changes, which is
most noticeably shown in their movement in spring. Therefore glaciers without IDS are passive and react to
climate changes poorly. IDS role increases at the stage of glaciers destruction or at glaciers tongues after
surge. IDS development very often provides accelerated glaciers destruction when other ablation types are
not possible (debris-covered glaciers). IDS played an important role in destruction of the glacial sheet in the
last glaciation during its degradation.
KEY WORDS: glaciers hydrology, internal drainage, climate change
Introduction
Apparently J.D. Forbes (1845, page 19)
was one of the first who considered IDS of
glaciers as a unit. He stated that «water is
cooled up to a freezing point, filters through
cracks in ice by uncountable jets which are
united below its mass and expand up to the
main stream». And further «streamlets which
as a complicated system of a superficial
drainage... These streamlets combined and
united in larger streams… They run in the ice
channels dug by them… They seldom however
followed the course far but reached cracks or
cavities in a glacier that were mechanically
formed. During movement they were falling
down by the cascade in their ice guts – there,
where they most likely formed a stream which
followed from glacier tongue».
W. Hopkins (1845) also considered that
subglacial streams were formed during ice
melting on the glacier surface and meltwater
penetrated through the open crevasses from the
glacier surface to the bottom and moved
further under the glacier. It was also believed
that the effect of the streams action on the
lower part of the glacier was due to hydrostatic
pressure was probably more significant than
their influence on the glacier surface. In his
opinion water penetrating ice should reach
glacier bottom in almost every point but it
cannot gather and create continuous channels
as they would be destroyed by glacier
movement. In his opinion possible obstacles
for water circulation and formation of
subglacial reservoirs is proved by constant
streams falling from the glacier tongue during
the nights when there is no melting on glacier
surface and when there is no water flow from
glacier surface.
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Bulat R. Mavlyudov
I.V. Mushketov (1881, page 647) writes the
following about glaciers drainage: «Water
stream on a glacier surface flows into
crevasses and mills and getting into crevasses
finally reaches the deepest part of a glacier.
Thanks to a slightly raised temperature this
water connected to several springs outflows
from glacier bottom washes ice away and
creates a free way to a valley».
The general principle of water circulation
inside of a glacier has been known since the
middle of 19th century, but the drainage
occurrence inside of glaciers was unknown for
a long time. Close to the middle of 20th
century S.V. Kalesnik (1939) wrote that there
was still very little known about internal
drainage. Basing on the results of investigation
in Alaska (Elgeln, 1912) it was supposed that
in large glaciers the internal drainage was
basically located in their marginal parts. In
small glaciers internal drainage could take
place along the glacier axial line. It was
assumed that some amount of channels could
be located within the ice not much below the
surface, possibly along the lower border of
crevasses. In case of glaciers retreat the
drainage can be marginal.
R.L. Shreve (1972, page 210) was one of
the first who considered glaciers drainage as a
system, he, «for the convenience of the
description», named its three components in
temperate glaciers: supraglacial, englacial and
subglacial. He was the first to prove that in
winter in subpolar glaciers where temperature
was equal to zero only at the bottom, as well as
in temperate glaciers, the whole supraglacial
component and a part of englacial component
were absent. It is possible to find all
components of a complex drainage system in
glaciers only in summer. Therefore
considering a supraglacial drainage system
supplying water into internal drainage system
through moulins and crevasses (in case of
drainage in karst areas) he believed that such
system existed for short periods of time when
the carrying capacity of englacial and
subglacial drainage systems adapted to the
increase of meltwater production at glacier
surfaces. Thinking of an internal drainage
network, he believed that it represented
arborescent channels system only in a part that
reached glacier surface as moulins absorbing
water from superficial water-streams, but
majority of channels was repeatedly branching
and collecting water from three-dimensional
network of inter ice grain channels water
circulation what was described in details in the
work of J.F. Nye (1976).
G.N. Golubev (1976) assumed that
hydrographic glacier network represented the
uniform interconnected hydraulic system, but
he didn't describe it in details.
There are many investigations that research
water inside glaciers (Paterson, 1984, Nye,
1976, Röthlisberger, 1972, etc.). But the
common principles of IDS structure described
by R.L. Shreve are still valid until these days.
Numerous investigations that demonstrated
separate IDS elements structure and features of
their regime have been carried out as well.
Research of water level fluctuations in glacial
moulins has shown that IDS are related to the
glacier movement and there are short periodic
and seasonal changes in separate IDS structure
elements (Iken, 1972; Iken, Bindschadler,
1986;
Badino,
Piccini,
2002,
etc.).
Investigations of features of glacial drainage
have allowed to determine its components that
drain water from ice and firn areas. It appears
that the majority of drainage is carried out
through channels with an overwhelming
proportion of drainage from ablation zone
(Golubev, 1976; Sokolov, 1977; Hodkins,
1998; Fountain, Walder, 1998; Wadham et al.
2001, etc.). Investigations of chemical
drainage from glaciers show that subglacial
water proportion rises during winter and falls
in summer when there is large meltwater
inflow to IDS channels (Krawczyk, 1998;
Hodkins, 1998; Wadham et al. 2001).
Geophysical research of glaciers (especially
radio-sounding and seismic-sounding) allowed
to find large water accumulations in ice
thickness of temperate glaciers and also to
determine boundaries between layers of cold
and temperate ice in polythermal glaciers
(Macheret, Zhuravlyov, 1980; Bamber, 1987;
Macheret, Glazovsky, 2000; Pattersson, 2004;
Navarro et al. 2005, etc.). In some cases radiosounding can show hypothetical situation of
Internal drainage systems of glaciers
englacial channels within the ice thickness
(Vasilenko et al. 2001).
There have been numerous paradoxical
situation in IDS studies: until now many
modeling works devoted to water circulation
inside of glaciers have been carried out while
direct
glaciological and hydrological
observations in channels inside glaciers haven't
been started. The authors of many
speleological modeling investigations that
have been carried on glaciers in various parts
of the world are unknown. It turns out that all
modeling works are based mainly on indirect
data. Therefore disputes and discussions about
details of glaciers IDS structure and the form
of subglacial channels are continued. The
theories explaining water circulation in ice
thickness and under glaciers are varied: from
various canalized flow (Nye, 1976;
Röthlisberger, 1972; Hooke, 1984) up to film
(Weertman, 1972; Nye, 1976; Shoemaker,
1999), movements of water through linkedcavities (Kamb, 1987), distributed channels or
in plastic or hard moraine sediments under
glaciers (Benn, Evans, 1998). There are
discussions about the form of channels in ice
and under glaciers. Most often it is assumed
that channels have semicircular (R-channels)
51
or flattened form of cross-section cut in
glaciers bottom (N-channels) or in ice (Rchannels) where drainage system is
arborescent (Röthlisberger, 1972), cellular
(Benn, Evans, 1998) or irregular with system
of interconnected small cavities behind ledges
of glacier bottom (Kamb, 1987), system of
similar cavities which cut through the central
main channel (Hooke, 1989), etc. There are
discussions about degree of water filling in
glaciers IDS channels: some researches
describe channels completely unfilled with
water (sometimes under pressure) (Nye, 1976,
Röthlisberger, 1972, etc.), others - about
channels partially filled with water (Hooke,
1984). Some researchers talk about the
importance of canalizing drainage inside of
glaciers (Röthlisberger, 1972), others consider
predomination of saturated water flow in
snow, firn and ice pores (Derikx, 1973). Thus
we see that there is no common opinion among
scientists on many key questions about glaciers
hydrology.
In this article we shall consider modern
concept of glaciers IDS based on the author's
own researches as well as the available results
of other speleological researches of channels in
glaciers.
Methodology
The author based it mainly on speleological
method of IDS investigations in this work. He
began to study glacier caves in 1982 on
Medvedzij (Bear) Glacier in Pamir (the area of
the former USSR) (Mavlyudov, 1991). In this
period the author investigated more than 70
subglacial and englacial caverns in glaciers of
Tibet, Pamir, Tien-Shan, Caucasus, Alps and
Spitsbergen. Apart from that he based the
research on the results of speleological
investigations that used mathematical models
and laboratory investigations (Mavlyudov,
2006). The main results of the author's IDS
investigations are contained in his book
(Mavlyudov, 2006).
IDS of glaciers
IDS can occur in all types of
temperate, polythermal and cold.
drainage systems structure is similar
them (Fig. 1). It means that the
drainage systems in all kinds of
develop in a similar way.
glaciers:
Internal
in all of
internal
glaciers
There are four main conditions of the origin
of internal drainage systems that are similar to
the origin of karst drainage systems (Sieger,
1895, Kruber, 1915): 1) presence of soluble
(melted) rocks, 2) presence of water that can
dissolve (melt) rocks, 3) occurrence of
aggressive water (possibility to dissolve rocks
52
Bulat R. Mavlyudov
or melted ice), 4) presence of water circulation
conduits (fissures and crevasses) inside of
rocks or ice. For internal drainage systems
formation some conditions should be added: 1)
sufficient quantity of meltwater on glaciers
surface (small quantity of water cannot form
channels; which means that concentrated water
streams are necessary); 2) ice temperature at
glaciers bottom not below -1°C. Otherwise
there will not be enough heat from water for
the channels in ice to origin.
subglacial water films, distributed channels,
water flow in subglacial sediments and so on
are not important for runoff. It means that
internal drainage in ablation areas of glaciers
constructed mainly by large enough englacial
and subglacial channels (Mavlyudov, 2007).
From the hydrological point of view it is
possible to divide IGS of glacier into the
following zones (Fig. 2): 1) absorption area,
i.e. the area where water penetrates into ice
from superficial streams (moulins entrances)
or percolates from snow and firn; 2) transition
area, i.e. englacial
and
subglacial
channels
with
water
(pits,
cascades, galleries)
– which is, in fact,
IDS; 3) entrance
area, i.e.
area
where
water
outflows
from
glacier
(glacial
caves
entrances,
upwellings).
Fig. 1. Schematic vertical section of glacier with
drainage system; on the right - dead ice massif (after B.
Mavlyudov, 2006). 1 - layer of cold ice; 2 - layer of
temperate ice; 3 – snow-firn deposits; 4 - englacial and
subglacial channels; 5 - glacial crevasses; 6 - layer of
moraine sediments; 7 - lakes water. I-IV - development
stages of glacial karst: I – early; II – young; III – mature;
IV – decrepit; I - accumulation area, II-IV – ablation
area. H - vadose englacial channels (Hooke channels); R
– freatic englacial channels (Röthlisberger channels); N freatic subglacial channels (Nye channels); Lc – linkedcavities channels in shadow of rock ledges; L – lakes.
Investigations show that in glaciers ablation
areas all systems of englacial and subglacial,
except the channels large enough, such as
veins between ice crystals, linked-cavities,
Fig. 2. Hydrology of IGS (after B. Mavlyudov, 2006). A
– absorption area, B – transit area, C – entrance area.
Short description of main IDS elements
We can subdivide IDS into some basic
elements (Fig. 3): 1) partly watered: moulins
and pits, cascades, galleries, caves; 2)
completely watered: sumps (siphons) or
galleries, upwellings and reservoirs.
Moulins and pits
Moulins – cylindrical subvertical hollows in
ice that are formed in place of open crevasses.
Stages of moulins development are shown on
Fig 4. Moulins usually form the IDS entrances.
The depth of the moulin depends on the depth
Internal drainage systems of glaciers
53
of crevasses. In temperate glaciers moulins
depth usually equals to 20-40 m and in
polythermal glaciers it equals approximately to
the depth of the upper cold ice layer
(Mavlyudov, Solovyanova, 2003).
develop but the cascade of small pits develops
directly from the glaciers surface.
Fig. 3. Elements of glacier internal drainage system (after
B. Mavlyudov, 2006).
Fig. 5. Channels formation on the base of single crevasse
(after B. Mavlyudov, 2006). 1 – crevasse, 2 – englacial
channels, 3 – water streams. I, II, III – numbers of water
streams flowing into one crevasse and forming 3
englacial channels.
Fig. 4. Pit formation from crevasse (after B. Mavlyudov,
2006). 1 – ice, 2 – crevasse, 3 – water stream, 4 disintegrating stream.
In geology a disk form is sometimes used
for a model of a fissure or a crevasse and a half
disk form is used for a surface opening
crevasses . The form of the first pit is different
depending on the place where the water stream
inflows into a half disk crevasse (Fig. 5). If
water stream inflows into the central part of a
crevasse, its depth is equal to maximum
crevasse depth. If water stream does not inflow
into the central part of a crevasse, its depth is
not the maximum and cascades of small pits
develop from the bottom of the entrance pit. If
water stream inflows at the lateral part of a
crevasse big entrance, a single pit does not
Fig. 6. Channels formation on the base of two intersected
crevasses. 1 – crevasses, 2 – channels, 3 – water streams.
I-I and II-II – plains of crevasses; A and B – numbers of
water streams and channels.
At the bottom of a crevasse the water
stream flows to the next crevasse and widens
54
Bulat R. Mavlyudov
itself to an englacial channel (Fig. 6). In such
way the water stream moves from one crevasse
to another up to the existing IDS channel.
Cascades
The cascades of small pits are developed on
the inclined surfaces of crevasse or at the
edges of disks form crevasses. Those cascades
are a combination of intermittent pits and
pools. The pits depth and pools length depends
on the initial inclination of crevasse. If the
inclination of the crevasse side (or the edge of
a disk crevasse) has a large enough angle, the
cascade has large (deep) pits and short pools.
If the inclination of the crevasse side (or the
edge of a disk crevasse) has a small enough
angle, the cascade has small (shallow) pits and
long pools (sometimes there may be pools
connected with the inclined ice surface that
end at the next pit). In moulins we observe pits
in cascades from 0,3 to 18 m and pools from
0,5 to 10 m.
Sometimes cascades begin to develop if
base level of water streams in IDS changes.
Galleries
The galleries are tubular forms of englacial
or subglacial channels that have subhorizontal
or inclined profile. Galleries develop from the
bottom of the entrance pits of moulins if the pit
comes to the crevasse bottom and water flows
along its bottom. Galleries usually have
meander channels in their plan. First of all
many meanders are connected to transverse
crevasses. In the cross-section the galleries
usually have vertical lengthening so that their
height is much larger than their width (vadoze
galleries). The channel width depends on the
discharge of water stream. If the water
discharge is about 50 l/s, the channel width
does not exceed 2 m. In case of a stream with
about 200 l/s, the channel width is less than 5
m. The ratio of height to width can vary from 2
to 30. In many cases in galleries it is possible
to see a system of parallel longitudinal grooves
and crests which are traces of the periods of
floods resulting from rains and increase of
melting. Sometimes it is possible to find a part
of the phreatic galleries at the end of an
investigated system of channels. Such channels
have a little elongated (ratio 1,1-1,5) or round
(ratio 1) cross-section. Galleries are usually
connected with fully watered channels through
sumps.
Caves
The caves are tubular subglacial forms and
more rarely englacial channels that have
subhorizontal or slightly inclined profile.
Caves are connected to completely watered
(phreatic) channels through sumps from one
side and opened to the air from the other side.
Caves can develop on the base of ice-rock
contact (in temperate glaciers) or on
subhorizontal crevasses (in polythermal and
cold glaciers) (Mavlyudov, 2005). In the crosssection caves usually have horizontal
lengthening so that their height is much lower
than the width. The ratio of height to width can
vary from 0,1 to 0,5.
Channels cutting from the ice surface
Some parts of IDS channels develop thanks
to water streams cutting into ice from glacier
surface and they are closed by snow and ice. It
is possible when the velocity of a stream
cutting is higher than the surface ice melting
(Fig. 7). In that way usually quite shallowly
cut channels develop. We haven't seen such
channels deeper than 30 m from the ice
surface.
Sumps (siphons) or watered galleries
Channels filled with water represent an
average part of IDS. In spite of that, normally
the longest parts of IDS are the most poorly
investigated. Investigating such channels is
possible only with a use of special diving
equipment, however such researches in many
cases are complicated or impossible because of
big water turbidity (up to the color of coffee or
milk). Because of it the question about the
structure of such channels in many cases still
remains open. We can only receive some
information about the structure of such
channels basing on individual divers'
researches in the glacial channels flooded with
clear water (Dominguez, Eraso, Jonnsson,
2002) and on the analysis of channels forms in
the marginal parts of IDS dried in an inter-
Internal drainage systems of glaciers
season period. The phreatic channels formed in
ice should be rounded and pipe-like.
55
modeled by vadose water and air streams for a
long time. Therefore round channels with a
diameter of 2 up to 5 meters and more
observed at the glaciers surfaces have nothing
in common with the primary forms of glacial
channels. A channels visible form corresponds
to the conditions of air circulation in their
inside.
Fig. 7. Drainage channel origin by canyon cutting from
glacier surface (after B. Mavlyudov, 2006). 1 – water, 2 –
snow, 3 – lowering ice surface.
Our investigations on Inyltchek Glaciers
(Tien Shan), Aldegonda and Aavatsmark
(Spitsbergen) and the data obtained from other
researchers on Tindal Glacier (Argentina)
(Badino, Piccini, 2002) have shown, that
phreatic channels have round tubular forms.
The size of such channels depends on waterstreams discharge. Undoubtedly in the drying
stage (the transitive autumn period), phreatic
channels are changed by vadose streams and
they can change their forms a little bit. A
gradual recession of stream discharge leads to
the greatest changes of a channel form. On the
contrary a fast stream discharge change leads
to minor alterations of the primary form of
channels. Modelling of phreatic channels by
vadose streams can occur only in marginal
parts of englacial IDS.
It is impossible to forget that all channels
that can be observed close to the glaciers
surfaces cannot serve as a prototype of
phreatic englacial channels as they haven't
been filled with water completely and strongly
Fig. 8. Glacial upwellings are formed: a - on edge of
polythermal glacier along subhorizontal crevasse in ice, b
- on edge of polythermal glacier along inclined crevasse
in ice, c - by dammed of channel in ice, d - on edge of
glacier from under icing, e - in channel in ice from
channel in rock, f - from channel in rock, g – along
crevasse system under icefall. 1 - glacial ice, 2 - icing ice,
3 – glacier bottom, 4 - moraine, 5 - rocks on glacier
bottom, 6 - upwelling (fountain) and place of water
inflow (arrow) (after B. Mavlyudov, 2006).
Upwellings
Caves are not the only way of water output
from the glaciers. So-called upwellings are
another frequent way of water output. This
term comes from oceanology where it means
oceanic waters rise in oceans thickness. In
glacial hydrology this term means a water
outflow in a form of fountains on the surface
or on the edge of glacier, on a naled (icing)
close to the glacier. Those fountains can have
varied heights from several centimeters up to
few meters and they are often described in
literature (for example, Theakstone, 2001).
Actually upwelling is an opening of a channel
completely filled with water on the glacier
56
Bulat R. Mavlyudov
surface. Water spouting is caused by pressure
difference of water in the tunnel at its outlet.
On some glaciers edges, ascending water
outflows or upwellings have been found at
glaciers tongues and on their surfaces. We
have observed upwellings at tongues of
glaciers Aldegonda, Eastern and Western
Grønfjord (Spitsbergen) and Southern
Inyltchek (Tien Shan). Most frequently
upwellings are formed at polythermal glaciers
tongues (Fig. 8). The formation of the
upwelling as a rule is related to fissures in
rocks, crevasses in ice and less frequently
channels in ice. On Fig. 8 it is possible to see
some variants of upwellings formation
investigated by the author personally and
coming from the literature analysis. The
existence of other upwellings types is not
excluded.
In our opinion the most frequent cases of
upwellings in polythermal glaciers are variants
a and d. In the first case the water outflows
from subhorizontal crevasse through a cover
moraine sediments on glacier tongue.
Lowering of the basis by erosion of a stream
outflowing from upwelling lead to a formation
of cave channel as it was observed at the
tongue of Western Grønfjord Glacier
(Spitsbergen) in 2004. In the second case the
water outflow occurs from under naled that
was marked on the glaciers Loven (Griselin et
al. 1995), East and Western Grønfjord
(Spitsbergen).
Reservoirs
Englacial and subglacial reservoirs
represent one of the most unstudied elements
of IDS on the glaciers. Until now it is not
known if they are isolated objects or they
represent separate parts of IDS active earlier
for any reason. As special researches of such
reservoirs have not been carried out while
there both points of view can exist.
Assumptions about the existence of such
reservoirs are related to unusual floods that
occurred independently of neither the time of
day, nor the weather, nor the rivers following
from under glaciers. Such water floods were
usually related to the outbreaks of internal
reservoirs in the ice (Jansson et al. 2003).
What can represent an englacial reservoirs?
First of all it is every open crevasse in the
thickness of ice space which is filled with
water. It is unknown how many such crevassereservoirs can exist in the ice thickness. It is
only known that such water filled crevasses
have been proved by numerous researches
(Fisher, 1963 and many others). Possibly the
greatest part of such crevasses is situated at the
top parts of the glaciers. We have observed
large enough lakes in open bergschrund
crevasses on Spitsbergen Glaciers, Aldegonda
and Tavle. On the glacier Fritjov (Spitsbergen)
water remained in numerous crevasses.
Numerous water accumulations inside of
the IDS also belong to the englacial reservoirs:
lakes and pools in cascades of pits, parts of
galleries flooded with water and phreatic
channels in the central parts of the glaciers. All
these reservoirs actually do not participate in
the water drainage and at the runoff ending
they are not dried. The amount of their water
exchange depends on the volume of these
reservoirs and the amount of the water-inflows
into them. When the reservoirs are of great
volume and of small water-inflow into them,
the water in the reservoir can be exchanged
completely only within a large interval of time.
And if there are some reservoirs of that type
along the waters way, the water circulation
inside the IDS can be slowed down essentially.
It is clear that separate places of IDS can
work as temporary water accumulators. We
have observed water filled cavities on the
glacier Aldegonda (Spitsbergen) with the
volume of at least 1130 and 3000 m3.
Reservoirs in IDS channels are a
widespread enough phenomenon which shows
findings of the large number of moulins filled
with a secondary ice on the polythermal
glaciers. Rather large ice crystals located in the
central parts of «star structures» prove the
simultaneous freezing of great water volumes.
Large amount of such «healed» moulins in
Aldegonda Glacier (Spitsbergen) confirm the
existence of essential volumes of water
reservoirs in the glacier
From what is said above we can conclude
that the glaciers can contain water in englacial
and subglacial reservoirs which are isolated
Internal drainage systems of glaciers
from channels of existing IDS for some time.
In our representations only the existence of
isolated IDS parts can become the reason of
unexpected floods in such cases when
temporarily broken connection of reservoir and
IDS is restored. IN case of reservoirs in
57
crevasses water filled unexpected breaks of
water in IDS channels are possible but they are
less probable, and apart from the usual
reservoirs volume in crevasses they are
insufficiently large to cause appreciable floods.
Discussion
The results of long-term IDS researches
shown in the previous work (Mavlyudov,
2006) and partially above allowed to formulate
briefly the main ideas about the origin,
formation and evolution of IDS in glaciers.
A. IDS formation
A1. IDS are formed by a method of joining i.e.
gradual addition of new channels located in a
glacier to previously formed IDS parts;
Consequences: 1) IDS cannot be formed in one
stage; IDS are in a formation stage during the
whole glaciers life; 2) Glacier changes lead to
IDS change; 3) New crevasses and parts of
previously existing channels participate in IDS
formation; 4) IDS have a special structure
inherent only to a certain glacier structure at
that moment in the particular climate at all
times.
А2. IDS channels can be formed first of all at
the base of crevasses or at the ice-rock contact.
Consequences: 1) Channels distributed under a
glacier have a secondary value and practically
do not participate in water drainage in the
glaciers; 2) Channels inside the glacier and on
its bottom have a limited distribution in the
area and in the volume (usually less than few
percent of volume); 3) It is possible to find R
and H channels of active IDS, various crevasse
channels that connect one reservoir to another,
and also N channels on the glacier bottom and
within the ice thickness ; 4) Water drainage
channels from polythermal glaciers are formed
along subhorizontal crevasses at glaciers
tongues; 5) The location of IDS channels in the
ice thickness, in a great degree, is defined by
the field of crevasses instead of equipotential
surfaces location; 6) Reorganization of
channels from a conformity with crevasse field
into influence of equipotential surfaces
probably occurs in the lowermost parts of IDS.
А3. The channels developed by water streams
cutting into ice from glacier surface have a
secondary value. Consequences: 1) Marginal
channels and shallow situated central channels
(so-called "hypodermic" channels) can develop
in such way; 2) Sometimes such channels
develop at the water outbursts from glacial
lakes; 3) The channels cutting into ice have
independent value or are tributaries to crevasse
channels; 4) Channels cutting into ice are
formed in glaciers of all types.
А4. The form of IDS channels depends on the
parameters, sizes and orientation of primary
crevasse, the previous history of channel
formation and evolution, the tension in ice.
Consequences: 1) It is possible to restore only
the most recent history of the channels
formation (usually 1-2 years) using its form ;
2) It is possible to restore the recent tension
field in the ice and the features of water
drainage using the channel form; 3) It is
possible to restore the history of the channels
development during several years using their
forms in upper and lower IDS parts.
B. IDS structure
B1. IDS structure is homogeneous in the
glaciers of all types and all sizes.
Consequences: 1) When we know the places of
water absorption and outflows, it is possible to
estimate the approximate IDS dimensions; 2)
Common IDS structure analysis does not allow
to determine the thermal conditions and
parameters contained in the glacier; 3) Despite
of the similarity of channel forms in different
glaciers, it is possible to determine the thermal
conditions and activity of a particular glacier
by separate parameters and dynamics of IDS
58
Bulat R. Mavlyudov
channels change; 4) Knowing the glacier
parameters (surface height and inclination,
dimensions of catch basins of separate
moulins), it is possible to estimate approximate
morphological characteristics of IDS channels
in a glacier.
B2. Moulins depth is approximately equal to
the thickness of cold ice layer. Consequences:
1) The depth of the entrance pits in moulins is
more or less equal on one glacier ; 2) Using the
depth of the entrance pits in moulins, it is
possible to estimate the cold ice layer
thickness and its variability on the glacier area.
B3. In temperate and cold glaciers IDS
channels direct towards the bottom.
Consequences: 1) The dynamics of movement
changes in temperate and cold glaciers is
located at the bottom; 2) All perturbations
caused by water in IDS channels are
transmitted to the glacier bottom (formation of
new crevasses, water diffluence etc.);
B4. In polythermal glaciers IDS channels are
located in the lower part of the cold ice layer.
Consequences: 1) The dynamics of movement
changes in polythermal glaciers is located at
the contact of cold and temperate ice instead of
the glacier bottom; 2) All perturbations caused
by water in IDS channels are transmitted
towards the boundary of temperate and cold
ice (formation of new crevasses, water
diffluence, etc.);
B5. The channel dimensions in the ice and
under the ice correspond to a discharge of
water stream (409). Consequences: 1) The
greater channel corresponds to the greater
stream and vice versa; 2) Big water streams
cannot "resolve" into many small ones, but
small channels can be united into a large one;
3) Changes of the discharge of water stream do
not lead to a change of channel dimensions
(system inertia) immediately; 4) The reduction
of water supply for a channel leads to its shortterm or seasonal closing; seasonal channels
closing leads to the formation of isolated water
reservoirs; 5) The channel form cannot
correspond to the water stream discharge
when: a) the channel is formed in a zone of
water spray (in pits); b) channel is formed in
the conditions of incomplete water filling.
B6. Channels are closed because of the plastic
deformation of ice.
Consequences: 1) A channel closing during the
ablation season is compensated by the channel
walls melted by the water streams (water
pressure overcomes the ice plasticity); 2) The
channels that lost water supply become
isolated because of the plastic deformation of
ice; 3) The period of closing dead channels
depends on their distance from the ice surface
and on the ice temperature (temperate ice is
more plastic, cold - is more rigid): the channels
in temperate glaciers are closed more quickly
(within months), and in cold ice - more slowly
(within years); 4) The channels are closed nonuniformly in vertical and in horizontal
directions that are defined by the ice
movement and by a non-uniform distribution
of the ice temperature (in vertical direction); 5)
in cold glaciers the reduction of channels
dimensions is also related to freezing of the ice
on cavity walls.
C. IDS dynamics of glaciers
C1. Each element of IDS has both a seasonal
and a long-term development cycles.
Consequences: 1) The cycle of separate
elements
development
doesn't
always
correspond to the cycle of the whole system
development; 2) The change of the system
neighboring elements is always related and
coordinated; 3) The degradation of separate
elements in an active system is possible in case
of the occurrence of new alternative IDS
elements; 4) A change of IDS elements
corresponds to the dynamics of the water
streams supply.
C2. All IDS have both a seasonal and a longterm cycles of development. Consequences: 1)
The seasonal cycle of IDS development is
related to the glacier internal structure and the
seasonal climate changes; 2) The long-term
cycle of IDS development is related to the
dynamics of the climatic changes and the
glacier dynamics.
C3. The existence of IDS is determined by its
stability in time. Consequences: 1) IDS
stability depends on the stability of its
elements; 2) IDS channels depend on the
stability of water supply: short (daily) supply
fluctuations render weak influence on the
Internal drainage systems of glaciers
system, long – term supply fluctuations (rains
or snowfalls) can promote channels expansion
or closing that upsets IDS stability; 3) IDS
channels stability depends on the ice
temperature: in cold ice the channels are more
stable than in temperate; 4) A significant
influence on IDS preservation during winter
may occur inside of the glaciers with isolated
water-filled reservoirs where the water is under
high hydrostatic pressure or where in spring an
incentive signal expressed in creation of water
pressure in upper IDS channels reservoirs is
united and where IDS are restored; 5) The
stability of IDS separate elements can be
determined by specific conditions (for
example, a permanently existing karst channel
at the glacier bottom absorbing glacial water).
C4. IDS dynamics depends on the ice
temperature. Consequences: 1) In cold rigid
ice the channels are stable (less dynamical); 2)
In temperate ice the channels are very dynamic
(unstable) and react sensitively even to shortterm (intradaily) changes of water stream
discharges.
C5. IDS changes with a glacier. Consequences:
1) IDS are replaced with the glacier retreat
and its degradation: on glacier tongue the
outflow channel is cut off by ablation and in
the upper part of the system it increases due to
the connection with new channels; 2) In
spreading glaciers IDS become less stable as
they have no time for reconstruction after and
during ice movement.
C6. Long-term IDS dynamics depends on the
tendencies
of
the
climate
change.
Consequences: 1) Determining of IDS
development in temperate glaciers is not a
short-term climate fluctuation, but a general
tendency of climate changes. 2) IDS in
polythermal glaciers react to the climate
changes more quickly and at a reduction of
glaciers size IDS completely disappear.
C7. Age of separate IDS channels depends on
glaciers mobility. Consequences: 1) In slowly
moving glaciers IDS elements age is estimated
at several years (up to 6) and in active glaciers
(for example, outlet glaciers) it can be
probably estimated at decades; 2) IDS age is
always more than the age of its separate
elements; 3) While the age of separate IDS
59
elements is estimated only at some years, ice
age is estimated at hundreds of years. IDS can
exist inside a glacier for at least hundreds or
even thousands years.
C8. IDS development is supervised by the
glaciers morphology. Consequences: 1) The
following factors influence IDS development:
the dimension of crevasse zones and the
presence of icefalls, ice surface inclination,
layer of cold or seasonally cooled ice
thickness, etc. and glaciers movement that may
influence IDS elements position in the ice
thickness or their fast destruction (in surging
glaciers). 2) There is a direct relation between
the ice activity and the time of the existence of
IDS cavities in glaciers: in active glaciers IDS
are shorter-living and in passive - longerliving; 3) The analysis of IDS cavities time
existence allow to estimate the glaciers
conditions.
C9. IDS have complex influence on the
glaciers. Consequences: 1) IDS serve as a
transmitters of climatic signals inside the
glaciers, therefore the glaciers react so quickly
to any climate changes; 2) IDS displace ice
mass balance inside the glaciers; 3) IDS
change the movement of an ice; 4) IDS
regulate glaciers drainage; 5) IDS change the
thermal field of a glacier; 6) IDS provoke
glacier surges; 7) IDS promote the drainage of
glacial lakes; 8) IDS promote fast degradation
of stopped or slowly moving glaciers («glacial
karst»); 9) IDS considerably change the
structure of water horizon in glaciers;
C10. IDS dynamics depends on the local
climate. Consequences: 1) The intensity of
growth of IDS channels grows with the
increase of average summer temperatures
which corresponds to the north to south
movement; 2) IDS react to the climate cooling
quicker than to the climate warming; 3) In the
process of strengthening the climate
continentality and lowering of active ice layer:
a) temperature conditions of IDS formation get
worse; b) the channels density per a volume of
ice unit decreases; c) displacement of the basic
volumes of IDS channels towards the glaciers
bottom due to the growth of the thickness of
upper cold ice layer increases; d) the downturn
of the position of moulins absorbing water in
60
Bulat R. Mavlyudov
relation with ELA of glaciers; e) the reduction
of complex fields describing potential IDS
development (in the seaside climate there are
fields on the glaciers of ablation and
accumulation areas and in the continental
climate - only ablation areas).
D. Drainage through IDS
D1. Basic water drainage from glaciers occurs
through N and R channels. Consequences: 1)
IDS consists basically from N, R and H
channels; 2) Water drainage through other
channels in glaciers is in the subordinated
position; 3) IDS channels determine water
drainage of majority of temperate and
polythermal glaciers;
D2. Water accumulation occurs in reservoirs
which basic part represents dead IDS parts.
Consequences: 1) Unexpected short-term
changes of water stream discharge following
from under glaciers are connected with shortterm channels damming or water outbreaks
from isolated IDS parts;
D3. Share of water drainage from glacier
depends on IDS development. Consequences:
1) The more intensively IDS are developed in
glaciers the bigger share of drainage passes
through them. 2) Water drainage from glaciers
in many respects is determined by character of
IDS development in them; 3) For large glaciers
share of internal drainage will be higher, than
for small ones.
D4. Water drainage through IDS depends on
weather. Consequences: 1) IDS during and
after snowfalls tin its development since
quantity of water flow through them decreases;
2) IDS in time of downpours accelerates its
development since quantity of water flowing
through them increases; 3) At steady weather
development IDS occurs uniform;
E. IDS and glaciers movement
E1. Increase of water pressure in IDS channels
as a result damming conducts to acceleration
of glaciers movement. Consequences: 1)
Changing character of glaciers movement
testifies to dynamic of their IDS development;
2) Increased water pressure in channels
conducts to crevasses formation and waters
flowing through them along glacier bottom or
along boundary between temperate and cold
ice;
E2. In specific conditions of water damming
there are conditions for glaciers surging.
Consequences: 1) Such damming can occur
only in conditions of inefficient IDS
development which is possible in conditions of
non-uniform ice movement; 2) Damming
causes destruction of IDS channels,
transporting water to bottom or to boundary
between temperate and cold ice.
E3. Any water reservoir affects an ice creating
field of tension in it. Consequences: 1)
Originated tension field in ice aspires to be
distributed on glacier and to relax that is
shown in acceleration of glacier movement or
in different orders crevasses formation; water
is directed into crevasses and if it will finds
exit pressure in system will fall; 2) IDS is the
factor of instability of glaciers creating tension
field at channels filling by water; at the same
time IDS is the factor of glaciers stability as its
allows to relieve the tension at water
expiration through created new or expanded
old channels; 3) Bore holes also affect on
tension field of glaciers in some cases forming
new crevasses at their lower parts (this process
demands special studying); 4) In a view of it
IDS are very dynamical, sensitively and
quickly reacting on any changes in inflow of
melt water;
E4. Presence in IDS glacier promotes glacier
movement. Consequences: 1) Glaciers without
IDS move very slowly and uniform; 2) In
conditions of temporary water damming in
IDS channels movement of glaciers becomes
non-uniform; 3) At absence of water damming
in IDS channels for glaciers rather fast uniform
movement is typical.
F. IDS and glacial karst
F1. Development of glacial karst promotes
preservation of ablation intensity on certain
quasi constant level. Consequences: 1)
Without dependence from thickness of covered
moraine at presence of water-streams
destruction of glaciers are not slowed down; 2)
At growth of moraine cover thickness drainage
from glacier practically does not change.
Internal drainage systems of glaciers
F2. On one glacier it is possible to meet all
phases of development of glacial karst.
Consequences: 1) Dimensions of zones
covering each stage of glacial karst
development depend on thermal conditions of
glacier and features of its dynamics;
F3. Lakes on glaciers surface accelerate ice
ablation.
Consequences:
1)
Ablation
acceleration on debris-covered glacier surfaces
occurs due to melting on exposed lake boards
and calving into lakes; 2) Ablation acceleration
on clean ice occurs due to smaller albedo of
water surfaces.
F4. Accelerated ice destruction from inside is
connected with "wandering" of water streams
in ice thickness and under glaciers.
Consequences: 1) Ice destruction occurs both
due to thermoerosion, and due to mechanical
destruction of developed ice collapses and
blockages above IDS channels; therefore for
limits of a glacier great volume of ice
fragments of an (pseudo calving) is carry out;
G. IDS and surging glaciers
G1. Surges occur during moments of steady
damming of IDS channels in favorable
conditions of ice mass accumulation.
Consequences: 1) Surge occurs when canalize
drainage is changed on water distribution on
glacier bottom; 2) Ice starts to be crushed at
changes of conditions of ice movement
(slipping) in valley.
G2. In polythermal glaciers motion occurs on
contact of cold and temperate ice.
Consequences: 1) Ice movement as pseudoplate lead to increase of surge duration.
H. IDS and lakes outbursts
H1. Outbursts of glacial lakes occur by
spillway through crevasses. Consequences: 1)
Lakes can lost water through crevasses
initiated by glacier movement or by weight of
lake; 2) Lakes are emptied more quickly if
appeared crevasses find connections with IDS
channels.
61
H2. Outbreaks of edge glacial and glacierdammed lakes occurs by spillways or through
channels at partial ice floating. Consequences:
1) Outbreaks more often occur in existing IDS
channels that considerably reduces water
movement way through ice; 2) Small lakes are
steadier than large; 3) The more the sizes of
lake the easier it can finds way for water
outburst and the shorter periods between
outbreaks;
H3. Outbreaks of glacier-dammed lakes
conduct to IDS reorganization. Consequences:
1) At the beginning of water outbreak from
lake influence of outflow water has
progressive creative character - there is an
expansion of IDS channels; 2) After lake
outbreak ending there will be destruction of
IDS channels;
I. IDS and glacier structure
I1. Character of IDS and superficial drainage
development
reflect
glacier
structure.
Consequences: 1) On the basis of this position
it is possible to construct monitoring of
drainage systems on glaciers including remote
which allows to determine tendencies of
glaciers change as a reflection of climate
changes.
The general provisions of the new concept
of IDS formation, development, dynamics and
evolution within the limits of glaciers have
been above shown. The set of positions
corresponds to a modern condition of level of
glaciers IDS investigations and in the further it
is planned to add. In spite of the fact that some
positions of the concept go to a cut with the
standard theories and hypotheses they better
describe processes occurring in IDS and allows
to look at many processes occuring in glaciers
in a new fashion. In other words IDS
investigations allows to uplift knowledges of
glaciers on a new qualitative level. Therefore
at the further studying glaciers research of
their IDS becomes an absolute must.
Conclusion
Internal drainage system construction from
enough big channels lead to: 1) quick water
flow through glaciers; 2) quick adaptation of
channel systems to changing conditions of
water flow; 3) quick external climatic signal
movement inside glacier (because of it glaciers
62
Bulat R. Mavlyudov
have very quick reaction on climate change);
4) possibility to accumulate water in dammed
channels and crevasses (internal water
reservoirs); 5) possibility to regulate (increase
or decrease) internal tension in glacier ice and
glacier movement.
Existence of internal drainage system in
glaciers lead to: 1) glaciers can move not as
hard plates (ice sheets) but as ice streams; 2)
glaciers can drain ice-dammed lakes; 3) in
glaciers exists regulated structure of water
runoff; 4) glacier surges exists; 5) quick ice
melting at slow moved glaciers as local mass
balance changing; 6) glaciers very quickly
react to climate change.It means if glaciers
would not contain internal drainage systems
they will be not so as we see now.If glacier not
contain internal drainage system it: cannot
moves quickly (as ice sheet); melts
predominantly from surface; has no water
runoff regulation; has very slow mass
exchange between upper and lower parts; can
be as part of passive glaciation if it will be
moraine-covered (or real dead ice).
Applied significance of internal drainage
systems in glaciers: allows to control GPR
data; allows to construct real models of
glaciers internal drainage in different kinds of
glaciers; allows to predict glacier movement;
allows to predict reaction of glaciers on
climate change; allows to predict glacier
surges (in some cases).
Acknowledgement
The author is grateful to professor V.N.
Golubev and corresponding member of
Russian Academy of Science I.A. Zotikov, and
also to employees of glaciological department
of Institute of geography RAS for valuable
remarks and discussions of separate elements
and all work. Work was executed at support of
grant НШ-9757.2006.5.
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