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| Titel |
Mathematic modeling of complex aquifer: Evian Natural Mineral Water case study considering lumped and distributed models. |
| VerfasserIn |
Abel Henriot, Bernard Blavoux, Yves Travi, Patrick Lachassagne, Olivier Beon, Benoît Dewandel, Bernard Ladouche |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250080440
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| Zusammenfassung |
| The Evian Natural Mineral Water (NMW) aquifer is a highly heterogeneous Quaternary glacial deposits complex composed of three main units, from bottom to top:
- The “Inferior Complex” mainly composed of basal and impermeable till lying on the Alpine rocks. It outcrops only at the higher altitudes but is known in depth through drilled holes.
- The "Gavot Plateau Complex" is an interstratified complex of mainly basal and lateral till up to 400 m thick. It outcrops at heights above approximately 850 m a.m.s.l. and up to 1200 m a.m.s.l. over a 30 km² area. It is the main recharge area known for the hydromineral system.
- The “Terminal Complex” from which the Evian NMW is emerging at 410 m a.m.s.l. It is composed of sand and gravel Kame terraces that allow water to flow from the deep “Gavot Plateau Complex” permeable layers to the “Terminal Complex”. A thick and impermeable terminal till caps and seals the system. Aquifer is then confined at its downstream area.
Because of heterogeneity and complexity of this hydrosystem, distributed modeling tools are difficult to implement at the whole system scale: important hypothesis would have to be made about geometry, hydraulic properties, boundary conditions for example and extrapolation would lead with no doubt to unacceptable errors.
Consequently a modeling strategy is being developed and leads also to improve the conceptual model of the hydrosystem.
Lumped models mainly based on tritium time series allow the whole hydrosystem to be modeled combining in series: an exponential model (superficial aquifers of the "Gavot Plateau Complex"), a dispersive model (Gavot Plateau interstratified complex) and a piston flow model (sand and gravel from the Kame terraces) respectively 8, 60 and 2.5 years of mean transit time.
These models provide insight on the governing parameters for the whole mineral aquifer. They help improving the current conceptual model and are to be improved with other environmental tracers such as CFC, SF6.
A deterministic approach (distributed model; flow and transport) is performed at the scale of the terminal complex. The geometry of the system is quite well known from drill holes and the aquifer properties from data processing of hydraulic heads and pumping tests interpretation.
A multidisciplinary approach (hydrodynamic, hydrochemistry, geology, isotopes) for the recharge area (Gavot Plateau Complex) aims to provide better constraint for the upstream boundary of distributed model. More, perfect tracer modeling approach highly constrains fitting of this distributed model.
The result is a high resolution conceptual model leading to a future operational management tool of the aquifer. |
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