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| Titel |
Physical and numerical modeling of seawater intrusion in coastal aquifers |
| VerfasserIn |
Elena Crestani, Matteo Camporese, Paolo Salandin |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250128345
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| Publikation (Nr.) |
 EGU/EGU2016-8328.pdf |
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| Zusammenfassung |
| Seawater intrusion in coastal aquifers is a worldwide problem caused, among others factors,
by aquifer overexploitation, rising sea levels, and climate changes. To limit the deterioration
of both surface water and groundwater quality caused by saline intrusion, in recent years
many research studies have been developed to identify possible countermeasures, mainly
consisting of underground barriers. In this context, physical models are fundamental to study
the saltwater intrusion, since they provide benchmarks for numerical model calibrations
and for the evaluation of the effectiveness of general solutions to contain the salt
wedge.
This work presents a laboratory experiment where seawater intrusion was reproduced in a
specifically designed sand-box. The physical model, built at the University of Padova,
represents the terminal part of a coastal aquifer and consists of a flume 500 cm long, 30 cm
wide and 60 cm high, filled for an height of 49 cm with glass beads characterized by a d50 of
0.6 mm and a uniformity coefficient d60/d10 ≈ 1.5. The resulting porous media is
homogeneous, with porosity of about 0.37 and hydraulic conductivity of about 1.3×10−3
m/s. Upstream from the sand-box, a tank filled by freshwater provides the recharge to the
aquifer. The downstream tank simulates the sea and red food dye is added to the
saltwater to easily visualize the salt wedge. The volume of the downstream tank is
about five times the upstream one, and, due to the small filtration discharge, salt
concentration variations (i.e., water density variations) due to the incoming freshwater flow
are negligible. The hydraulic gradient during the tests is constant, due to the fixed
water level in the two tanks. Water levels and discharged flow rate are continuously
monitored.
The experiment presented here had a duration of 36 h. For the first 24 h, the saltwater
wedge was let to evolve until quasi stationary condition was obtained. In the last 12 h,
water withdrawal was carried out at a depth of 7 cm and at a distance of about
50 cm from the downstream tank by means of a draining trench. The experiment
was monitored by means of photos collected with regular frequency as well as
ERT (electrical resistivity tomography) with a joint surface and cross-borehole
configuration, specifically designed for the laboratory flume. The experimental results are
also compared with numerical simulations performed by the SUTRA software. |
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