Karst Sub-Marine Springs (KSMS). Michel BAKALOWICZ HydroSciences, CNRS Partner #2. Karst Sub-Marine Springs (KSMS). Why do KSMS exist? Where are KSMS located? Why should we take an interest in KSMS? How can we display KSMS? How can we study KSMS? How can we collect fresh water from KSMS?. - PowerPoint PPT Presentation
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7 & 8 May 20047 & 8 May 2004 MEDITATE Kick off meeting, Montpellier, MEDITATE Kick off meeting, Montpellier, Michel BAKALOWICZ Michel BAKALOWICZ
… … and around the and around the MediterraneanMediterranean
7 & 8 May 20047 & 8 May 2004 MEDITATE Kick off meeting, Montpellier, MEDITATE Kick off meeting, Montpellier, Michel BAKALOWICZ Michel BAKALOWICZ
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The Vise KSMS, in the Thau The Vise KSMS, in the Thau lagoon near Montpellier, at -29 lagoon near Montpellier, at -29
m…m…
1000 mm pipe, « the bell »1000 mm pipe, « the bell »
Fresh water plumeFresh water plume
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… at the sea surface
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Why should we take an Why should we take an interest in KSMS?interest in KSMS?
Groundwater leakage directly into the seaGroundwater leakage directly into the sea
Necessary assessment :Necessary assessment :
– In hydrological balances In hydrological balances
– For controlling the impacts of pumping in For controlling the impacts of pumping in
coastal aquiferscoastal aquifers
Potential groundwater resource in regions Potential groundwater resource in regions
with poor water resourcewith poor water resource
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How can we display How can we display KSMS?KSMS?
By local investigationsBy local investigations
By means of remote sensingBy means of remote sensing
By direct explorationBy direct exploration– made by divers : difficult and not really made by divers : difficult and not really
reliablereliable
– from a boat : requiring important from a boat : requiring important
measures and a long timemeasures and a long time
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Reliability of field Reliability of field investigationsinvestigations– Good knowledge about KSMS existence Good knowledge about KSMS existence
and locationand location
– Results not easy to interpret from remote Results not easy to interpret from remote sensing (2D picture of the sea surface)sensing (2D picture of the sea surface)
– Lowly reliable information from divers Lowly reliable information from divers about flow rates and fresh water quality about flow rates and fresh water quality (overestimation, mixing)(overestimation, mixing)
NO POSSIBLE QUANTIFICATION OF KSMS!
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From a boatFrom a boat
Mapping the fresh water plume Mapping the fresh water plume
from temperature and salinity from temperature and salinity
measurements and from samplesmeasurements and from samples
Necessary means : a boat + 1 or 2 Necessary means : a boat + 1 or 2
marins + 2 to 4 scientists with a marins + 2 to 4 scientists with a
multiparameter probe and multiparameter probe and
sampling bottlessampling bottles
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Sampling networkSampling networkaround the springaround the spring
Mapping the freshwater Mapping the freshwater plume in Thau lagoonplume in Thau lagoon
Bathymetry around the Vise KSMS
Isotemperatures ata 3 m depth
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Problems (1)Problems (1)
Using a boat:Using a boat:– 3 working days… 3 working days…
after several months waiting for good after several months waiting for good conditionsconditions
the boat and men, nice weather, no the boat and men, nice weather, no wind…wind…
– only 2 experiments within 3 years!only 2 experiments within 3 years!– sampling step between 25 and 250 sampling step between 25 and 250
mm
7 & 8 May 20047 & 8 May 2004 MEDITATE Kick off meeting, Montpellier, MEDITATE Kick off meeting, Montpellier, Michel BAKALOWICZ Michel BAKALOWICZ
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Problems (2)Problems (2)
With divers:With divers:
– Difficult to work at -30/-40 m depth, Difficult to work at -30/-40 m depth,
time consuming and expansivetime consuming and expansive
– Low reliability of observations : Low reliability of observations : Frequent overestimations of flow rates, Frequent overestimations of flow rates,
based on observed flow velocitiesbased on observed flow velocities Sampling everytime mixed with seawaterSampling everytime mixed with seawater
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How do we use the How do we use the data?data?
Building the freshwater plume in 3D Building the freshwater plume in 3D from :from :– the temperature fieldthe temperature field– the salinity fieldthe salinity field– the flow velocity fieldthe flow velocity field
Knowing the bathymetry and spring Knowing the bathymetry and spring depth, modelling of the plume for depth, modelling of the plume for different flow ratesdifferent flow rates
Then comparison of the simulated vs Then comparison of the simulated vs observed plume observed plume
7 & 8 May 20047 & 8 May 2004 MEDITATE Kick off meeting, Montpellier, MEDITATE Kick off meeting, Montpellier, Michel BAKALOWICZ Michel BAKALOWICZ
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Proposed approach :• from the bathymetry, a model simulates the velocity, temperature and salinity fields for several flow rates (from 50 to 1000 L/s).
Comparison simulated vs observed plume : QKSMS < 100 L/sEvaluations by divers and direct flow measurement : about 1000 L/s
7 & 8 May 20047 & 8 May 2004 MEDITATE Kick off meeting, Montpellier, MEDITATE Kick off meeting, Montpellier, Michel BAKALOWICZ Michel BAKALOWICZ
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Therefore we had got the Therefore we had got the
idea of developing an idea of developing an
autonomous engine for autonomous engine for
exploring a KSMS exploring a KSMS
freshwater plume rapidly freshwater plume rapidly
for repeating the data for repeating the data
acquisitionacquisition
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Which tasks Which tasks prescribed to the prescribed to the engine?engine? Control and recording the trajectoryControl and recording the trajectory
Measure of temperature and salinityMeasure of temperature and salinity
Measure of the velocity fieldMeasure of the velocity field
Pictures of the plumePictures of the plume
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How can we study KSMS?How can we study KSMS?
The Vise spring station on Thau lagoonThe Vise spring station on Thau lagoon
Measure well of the KSMSMeasure well of the KSMS(P, T, (P, T, 222222Rn, samplings)Rn, samplings)
Measure well of the lagoonMeasure well of the lagoon
To the data loggerTo the data logger
200 m long pipe200 m long pipeFrom the KSMSFrom the KSMS
7 & 8 May 20047 & 8 May 2004 MEDITATE Kick off meeting, Montpellier, MEDITATE Kick off meeting, Montpellier, Michel BAKALOWICZ Michel BAKALOWICZ