Summary
Summary Subglacial hydrology
- Course
- Institution
Exam notes on the subglacial hydrology of mountain glaciers, and how the switch from a distributed to channelised system occurs.
[Show more]
Seller
Follow
CambridgeGeography
Content preview
Intro• interested
in
glacier
hydrology
given
the
power
of
glaciers
to
influence
runoff
and
chemical
weathering
and
so
act
as
a
potential
geohazard
(Sharp,
2005).
• influence
drainage
configurations
on
water
storage
and
flow
(Benn
and
Evans,
2010).
• understanding
-‐
indirect
methods
(Sharp,
2005).
o radio-‐echo
sounding,
monitoring
boreholes
and
runoff
properties
and
artificial
tracing
(Sharp,
2005).
• Winter-‐spring,
meltwater
discharge
of
temperate
glaciers
increases
2
orders
of
magnitude,
hydrological
system
must
adapt
accordingly
(Fountain
and
Walder,
1998).
• subglacial
drainage
system
shifts
accordingly
from
a
‘distributed’
system
in
which
water
transport
to
the
tongue
is
slow
and
inefficient
to
a
‘channelized’
system,
which
transports
water
faster
and
more
efficiently.
Distributed
system
• 3
components
-‐
relative
hydrological
each
component
vary
space
+
time
(B
and
E,
2010)
o pervasive
water
film
§ exist
between
ice
and
the
underlying
sediment
§ transport
water
produced
at
the
bed
by
geothermal
heating
and
sliding
friction,
or
waters
involved
in
regelation
around
small
obstacles
on
the
glacier
bed
(Weertman,
1964).
§ Stable
up
to
very
small
thicknesses
of
around
4mm
o permeable
till
enabling
groundwater
flow,
§ Permeable
and
porous
subglacial
sediment
hypothesised
function
confined
aquifer
drain
water
from
glacier
bed
(Boulton,
1974)
§ probably
minor
role
(Sharp,
2005).
• Measured
hydraulic
conductivities
of
subglacial
sediments
are
low
(Fountain
and
Walder,
1998).
• Most
calculations
-‐
Darcian
flow
through
aquifers
of
thicknesses
around
0.1m
with
a
hydraulic
gradient
of
∼0.1
are
not
even
able
to
transport
discharge
of
the
winter
period
(Alley,
1989).
• Therefore
the
aquifer
will
become
saturated
and
drainage
systems
will
operate
on
its
upper
surface
(Sharp,
2005).
o a
linked
cavity
network
§ major
role
in
distributed
system
(Fountain
and
Walder,
1998)
§ Form
-‐
sliding
ice
separates
from
the
glacier
bed,
formation
favoured
by
rapid
sliding
and
high
bed
roughness
(Nye,
1970).
§ Lliboutry
(1976)
2
types
• autonomous
cavities
–
hydraulically
isolated
stagnant
meltwater
• interconnected
cavities
-‐
active
part
§ nonarboresecent
cavity
networks
-‐
linked
by
small
bedrock
(Nye)
channels
which
are
incised
up
to
0.2m
into
the
glacier
bed
(Nye,
1973).
§ Studies
recently
deglaciated
bedrock
surfaces
-‐
large
numbers
of
Nye
channels,
beneath
at
least
some
small
alpine
glaciers
(Sharp
et
al,
1989;
Fountain
and
Walder,
1998).
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller CambridgeGeography. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.79. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
71498 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now