• A hydraulic module that routes in-stream water flows using a Muskingum scheme
[81, 82], from which water levels are derived using rating curves [34] or a
manning approximation of a steady state [35, 69]. Computed discharges in each
river cell of the hydrographic network result from both stream–aquifer fluxes and
contributions from subsurface runoff.
3.2 Implementation of the Seine Basin Model
The surface layer of the model [45] covers an area of 81,200 km
2 including the entire
76,300-km
2 Seine basin. The grid is divided into elementary watersheds of an
average area of 11 km
2 , on which the surface water balance is calculated. The
river network implemented in the model is directly provided by the Carthage
national database
1 . In this application, both discharges and stream–aquifer exchange
calculations are restricted to the main river network (Fig. 6) describing 4,520 km of
rivers from Strahler orders 3–8 [83] at the mouth of the Seine River. While the first
implementation of the model described three aquifer units [33, 39], the aquifer
system was refined up to six aquifer units by Pryet et al. [35]. The current version,
developed by Labarthe [45], discretises the multilayered structure in seven aquifer
units, including alluvial plains, using a progressive multi-scale grid of nested square
meshes, with cells varying from 200 m to 3,200 m in size. The seven aquifer units
can be regrouped, from the oldest to the most recent, in three main ensembles [1]:
• A Cretaceous chalk aquifer that has by far the largest impluvium
• A five-layer Tertiary complex ensemble, located in the centre of the basin,
covering aquifer units mainly made of limestones and sands, dating from
Palaeocene to Miocene
• Quaternary alluvial deposits surrounding the basin’s main rivers
Jurassic aquifers, which outcrop at the eastern border of the basin, are not
represented as explicit aquifer layers and are treated by a subsurface procedure
using a simplified reservoir model in order to route infiltration fluxes towards the
hydraulic network.
4 Current State of the Seine Hydrosystem
A 17-year periodicity associated with the NAO was previously identified [50] on
observed climatic and stream discharge data over the Seine basin. Both groundwater
and river water storage have also been proved to be stationary over a 17-year period
1 http://www.sandre.eaufrance.fr.
66
N. Flipo et al.
[81, 82], from which water levels are derived using rating curves [34] or a
manning approximation of a steady state [35, 69]. Computed discharges in each
river cell of the hydrographic network result from both stream–aquifer fluxes and
contributions from subsurface runoff.
3.2 Implementation of the Seine Basin Model
The surface layer of the model [45] covers an area of 81,200 km
2 including the entire
76,300-km
2 Seine basin. The grid is divided into elementary watersheds of an
average area of 11 km
2 , on which the surface water balance is calculated. The
river network implemented in the model is directly provided by the Carthage
national database
1 . In this application, both discharges and stream–aquifer exchange
calculations are restricted to the main river network (Fig. 6) describing 4,520 km of
rivers from Strahler orders 3–8 [83] at the mouth of the Seine River. While the first
implementation of the model described three aquifer units [33, 39], the aquifer
system was refined up to six aquifer units by Pryet et al. [35]. The current version,
developed by Labarthe [45], discretises the multilayered structure in seven aquifer
units, including alluvial plains, using a progressive multi-scale grid of nested square
meshes, with cells varying from 200 m to 3,200 m in size. The seven aquifer units
can be regrouped, from the oldest to the most recent, in three main ensembles [1]:
• A Cretaceous chalk aquifer that has by far the largest impluvium
• A five-layer Tertiary complex ensemble, located in the centre of the basin,
covering aquifer units mainly made of limestones and sands, dating from
Palaeocene to Miocene
• Quaternary alluvial deposits surrounding the basin’s main rivers
Jurassic aquifers, which outcrop at the eastern border of the basin, are not
represented as explicit aquifer layers and are treated by a subsurface procedure
using a simplified reservoir model in order to route infiltration fluxes towards the
hydraulic network.
4 Current State of the Seine Hydrosystem
A 17-year periodicity associated with the NAO was previously identified [50] on
observed climatic and stream discharge data over the Seine basin. Both groundwater
and river water storage have also been proved to be stationary over a 17-year period
1 http://www.sandre.eaufrance.fr.
66
N. Flipo et al.