Coastal geomorphology post-doc position at IUEM/Brest (France)

Dear
all,
Please find a post-doc position profile in geomorphology
available at IUEM/Brest in France on cliff erosion: impact of
waves and groundwater flow on cliff micro-fracturation via the
link http://ift.tt/1Tt1wI7

Please feel free to contact Pauline Letortu
or Nicolas Le Dantec
for more information.

Cliff
erosion:
impact
of waves and
groundwater
flow on cliff
micro-fracturation

Keywords:
coastal
geomorphology;
coastal cliff
erosion;
micro-fracturation;
rock mechanics

 

Motivation

The
proposed
post-doctoral
research
project
addresses the
prevalence
between marine
and
continental
processes in
controlling
cliff erosion.
In addition to
direct wave
impact
(undercutting),
recent studies
(Young et al,
2012;
Earlie et al,
2015)
underline the
swaying effect
generated by
infragravity
waves
(downward and
seaward
micrometric
cliff-top
displacements
due to wave
loading). Such
micro-movements
can cause
micro-fractures,
reducing cliff
resistance and
therefore
acting as a
predisposing
factor to
failure.
Various
studies
emphasize the
role of
continental
factors,
including
precipitation,
which induce
reduced cliff
stability
through
runoff,
infiltration
and
groundwater
table
variations
(Lahousse
and Pierre,
2003; Duperret
et
al., 2004;
Lissak et al.,
2014).
Groundwater
flow is
particularly
dependent on
micro- and
macro-cracking.
Since both
marine
and subaerial
actions tend
to combine,
discriminating
their relative
contribution
is
challenging.
Hydrostatic
pressure,
generated by
groundwater
flow,
as well as sea
levels
fluctuations
due to wave
impact against
cliffs, can
extend
micro-fractures
within cliff
materials and
thus reduce
the mechanical
resistance
of cliffs,
promoting
their failure.
On the
contrary,
enhanced
microfracturation
may release
overpressure
within the
cliff.

 

Objectives, methodology
and study
sites

In a
context of
rocky cliffs
exposed to
oceanic
swells and in
macrotidal
regime, this
18-month
postdoctoral
project
focuses on
the impact of
waves and
groundwater
flow on
micro-fracturation
and subsequent
erosion of
cliffs in
Brittany. The
study will be
based on field
campaigns to
be
conducted at
two sites with
distinct cliff
lithologies. Three
main questions
will be
investigated:


Characterization
of cliff
micro-fracturation
from site
scale to
sample scale
(using
satellite
imagery, in
situ
observations
and
mechanical
tests in the
laboratory)
and
characterization
of
hydrogeology,
both
deep and
ground-surface,
at the scale
of watersheds
and of the
coastal fringe
(with
field analysis
tools and
numerical
modeling);


Monitoring of
micro-fracturation
and cliff
erosion in
relation to
wave impact
(using
measurements
from pressure
sensors,
accelerometers
and
sismometers to
evaluate the
hydrodynamical
forcing and
the mechanical
response of
the cliffs).
Both energy
dissipation
of wave
breaking on
the cliff face
and
wave-induced
sea-level
loading will
be
considered.
Because
dissipation of
incident wave
energy depends
on beach
morphodynamics
at the cliff
foot, beach
profile
topography
will be
monitored;


Monitoring of
micro-fracturation
and cliff
erosion in
relation to
runoff and
groundwater
flow
(setting-up a
network of
weather
stations and
piezometers).

The analysis of the dataset is
expected to
bring insight
into the
relative
contributions
of structural,
marine and
continental
factors in
cliff erosion
and retreat in
the context of
the study
sites in
Brittany and
elsewhere. The
originality of
the project
lies in the
concomitant
measurements
of
micro-fracturation
(using
accelerometers),
cliff-top
displacement
(with
seismometers),
wave
hydrodynamics
and
groundwater
flow, in
addition to
topo-bathymetric
surveys.

The
sites of
Déolen
in Plouzané
and Veryac’h
in
Camaret-sur-Mer
have been
selected
for this
project.
Déolen
consists of
plunging
cliffs carved
in gneiss. The
nearshore
bathymetry is
very
reflective and
reaches over
30m depth
within
hundreds of
meters of the
coastline. The
Veryac’h
cliffs are cut
as an erosion
platform into
a succession
of quartzite
and shale.
This site is
located to the
South
of Pen-Hir
bight, in a
dissipative
environment.
Pending on the
results
obtained
at these two
sites in
Brittany, a
similar field
survey may be
considered at
additional
sites
representative
of other cliff
types: cliffs
with a thicker
layer of
“head”
(periglacial
formations)
(Brittany
coast), chalk
cliffs
(Normandy),
sedimentary
rock cliffs
(California,
USA) in
collaboration
with the
University of
San Diego
(USA).

Job details

Eligibility:


The candidate
must have
obtained
her/his PhD
within the
last 5 years
in a relevant
speciality
of Physical
Geography
(Geomorphology),
Physical
Oceanography,
Geology,
Applied or
Environmental
Physics, or
Soil
Mechanics.

– 
The candidate
must either be
a foreign
national to
France or have
spent a
minimum of 12
months outside
France during
the last three
years (between
02/04/2012 and
02/04/2015).

Additional
requirements:

Proficiency
in
the following
areas will be
advantageous:


Knowledge-base
in the fields
of
geomorphology,
geotechnics,
geology, soil
mechanics and
fluid
mechanics;


Field
instrumentation
(including
pressure
transducers,
accelerometers,
seismometers,
piezometers,
DGPS,
terrestrial
laser scanner,
photogrammetry);


Data
processing
(Matlab, image
analysis,
satellite
image
processing);


Proven record
of scientific
publication;


Perseverance,
scientific
rigor, ability
for team-work;


Basics in
French and/or
willingness to
learn French
language.

Employment
conditions

Post-doc
duration:
18 months

Net
monthly
salary (Subject
to income
tax):
€ 2047

Host laboratory:
LETG-Brest
Géomer (http://ift.tt/1XAkT18)

Partner
laboratory:
LDO (http://ift.tt/1Tt1wI9)

Department:
IUEM
(Université de
Bretagne
Occidentale) (http://ift.tt/1XAkUSL)

The
post-doctoral
project will
be carried out
in the
framework of
the
partnership
between the
laboratory
‘LETG-Brest
Géomer’ and
the “Dynamics
of Littoral
and Coastal
Environments”
group of the
laboratory
‘Domaines
Océaniques’,
both teams
working on
coastal
morphodynamics
and
hydro-sedimentary
processes,
including in
the context of
the
axis 5 of
Labex MER (http://ift.tt/1Tt1wId)
and the topic
1 of the “Zone
Atelier
Brest-Iroise”
(http://ift.tt/1XAkUSM).

For
more
information
about this
position
contact the
PIs:
Pauline
Letortu (pauline.letortu@univ-brest.fr)
and
Nicolas Le
Dantec (nicolas.ledantec@univ-brest.fr)

Application
and
recruitment
process

To
apply,
send a
detailed CV
and research
statement to
the PIs (pauline.letortu@univ-brest.fr
and nicolas.ledantec@univ-brest.fr)

Position
must
be filled by
end of May
2016.
Applications
will be
reviewed
immediately
and until the
position has
been filled.

Claire Earlie   
LabexMER

Post-doctoral researcher

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