anthropogenic pressure on the groundwater resources, which in turn modifies the
biogeochemical functioning of the interface and greenhouse gas emissions [96]. The
consequences of such alterations on river ecology are still poorly understood and are
the focus of ongoing research [97, 98]. Heavy pumping removes 10 m
3 s
À1 from
alluvial plains connected to the downstream part of the river network (Strahler orders
>3). Half of it is taken up from the alluvial aquifers, and the other half is taken
directly from rivers through the natural upward motion of the water from the aquifer
to the river [35].
At the river–aquifer interface, water is exchanged upward and downward. The
absolute summation of these two is called “gross flux”, while the difference is called
“net flux”. At the Seine basin scale, the gross flux is 50% larger than the net flux.
During dry years, those proportions remain unchanged, while they increase by 50%
during wet years [35].
As conceptualised by Flipo et al. [72], most of the water exchanges along the
main river network take place in the stream–aquifer interface represented at this scale
Fig. 4 Averaged spatial distributions over the 1993–2010 period of (a) SAFRAN annual rainfall
and simulated, (b) annual AET, (c) annual infiltration, (d) annual runoff. Units in mm a
À1
Pluri-annual Water Budget on the Seine Basin: Past, Current and Future Trends
69
biogeochemical functioning of the interface and greenhouse gas emissions [96]. The
consequences of such alterations on river ecology are still poorly understood and are
the focus of ongoing research [97, 98]. Heavy pumping removes 10 m
3 s
À1 from
alluvial plains connected to the downstream part of the river network (Strahler orders
>3). Half of it is taken up from the alluvial aquifers, and the other half is taken
directly from rivers through the natural upward motion of the water from the aquifer
to the river [35].
At the river–aquifer interface, water is exchanged upward and downward. The
absolute summation of these two is called “gross flux”, while the difference is called
“net flux”. At the Seine basin scale, the gross flux is 50% larger than the net flux.
During dry years, those proportions remain unchanged, while they increase by 50%
during wet years [35].
As conceptualised by Flipo et al. [72], most of the water exchanges along the
main river network take place in the stream–aquifer interface represented at this scale
Fig. 4 Averaged spatial distributions over the 1993–2010 period of (a) SAFRAN annual rainfall
and simulated, (b) annual AET, (c) annual infiltration, (d) annual runoff. Units in mm a
À1
Pluri-annual Water Budget on the Seine Basin: Past, Current and Future Trends
69