between 1839 and the middle of the twentieth century, thus illustrating the slow
dynamic of the Seine River here [2].
From the 1950s onwards, the Bassée alluvial plain was exploited as gravel pits,
with an average of 37 ha transformed into gravel pits every year since then (BRGM,
1995). They are typically between a few hectares and 100 ha (Fig. 6), a few metres
deep, and most of them are filled with waters from the alluvial aquifer, which is
found between 0.5 and 1.25 m from the ground level in most locations [21].
Between 1839 and 2010, the waterscape of the Bassée was completely
transformed: in 1839, the natural Seine River channel covered 400 ha, and other
bodies contributed 70 ha. In 2010, the artificial navigated channel covered 340 ha,
the former river channels and associated natural waterbodies 360 ha and the waterfilled sandpits 1,783 ha. As a whole, the open waterbody coverage of this sector has
been increased five times. This tendency will continue in the near future with the
construction of artificial water storage compartments, totalling 2,300 ha for the
whole project, to store river water when Paris and its suburbs, some 100 river km
downstream, are threatened by inundation. Ten compartments are planned, separated
by 58 km of artificial dikes, up to 4.7 m high (http://www.seinegrandslacs.fr/leprojet-global-damenagement. Accessed 15 May 2019).
As a whole, this natural major wetland has been severely transformed for
navigation (channel rectification), for construction (gravel pits) and in the future
for flood control purposes (artificial water storage compartments): the mosaic of
former natural water bodies, flooded forest and wetlands has been replaced by
another mosaic of artificial water bodies, navigation channels and sandpits, with
greater depths, often steep slopes, limited aquatic vegetation and direct exposure of
the phreatic aquifer (which may result in a deterioration of the quality of groundwater used for drinking water supply). In the last 25 years, efforts have been made to
“renaturalise” these artificial waterbodies, particularly as bird refuges.
4.3 Simplification of Seine River Channel and Loss of Islands
In the last 200 years, the navigation on the Seine River has resulted in simplification
and deepening of the channel and regulation by locks. River map archives also show
that simultaneously most islands have been reconnected to the banks. Between the
1830s and today, 405 islands have been reconnected along the 340 km river course
from the Seine-Yonne confluence to Rouen in the Seine estuary [60]. The history of
these islands, their settlements and uses, is rarely told in classical archives as these
parts of the river area are seldom inhabited [61].
The cartographic archives, along with historical information on navigation structures, can be used to reconstruct their history. Figure 9 shows the modifications of
the river channel in the Poses sector (for location, see Fig. 1), which marks today’s
upper limit of the tidal influence, between 1846 (Ponts et chaussées map) and 2015
(IGN map).
50
L. Lestel et al.
dynamic of the Seine River here [2].
From the 1950s onwards, the Bassée alluvial plain was exploited as gravel pits,
with an average of 37 ha transformed into gravel pits every year since then (BRGM,
1995). They are typically between a few hectares and 100 ha (Fig. 6), a few metres
deep, and most of them are filled with waters from the alluvial aquifer, which is
found between 0.5 and 1.25 m from the ground level in most locations [21].
Between 1839 and 2010, the waterscape of the Bassée was completely
transformed: in 1839, the natural Seine River channel covered 400 ha, and other
bodies contributed 70 ha. In 2010, the artificial navigated channel covered 340 ha,
the former river channels and associated natural waterbodies 360 ha and the waterfilled sandpits 1,783 ha. As a whole, the open waterbody coverage of this sector has
been increased five times. This tendency will continue in the near future with the
construction of artificial water storage compartments, totalling 2,300 ha for the
whole project, to store river water when Paris and its suburbs, some 100 river km
downstream, are threatened by inundation. Ten compartments are planned, separated
by 58 km of artificial dikes, up to 4.7 m high (http://www.seinegrandslacs.fr/leprojet-global-damenagement. Accessed 15 May 2019).
As a whole, this natural major wetland has been severely transformed for
navigation (channel rectification), for construction (gravel pits) and in the future
for flood control purposes (artificial water storage compartments): the mosaic of
former natural water bodies, flooded forest and wetlands has been replaced by
another mosaic of artificial water bodies, navigation channels and sandpits, with
greater depths, often steep slopes, limited aquatic vegetation and direct exposure of
the phreatic aquifer (which may result in a deterioration of the quality of groundwater used for drinking water supply). In the last 25 years, efforts have been made to
“renaturalise” these artificial waterbodies, particularly as bird refuges.
4.3 Simplification of Seine River Channel and Loss of Islands
In the last 200 years, the navigation on the Seine River has resulted in simplification
and deepening of the channel and regulation by locks. River map archives also show
that simultaneously most islands have been reconnected to the banks. Between the
1830s and today, 405 islands have been reconnected along the 340 km river course
from the Seine-Yonne confluence to Rouen in the Seine estuary [60]. The history of
these islands, their settlements and uses, is rarely told in classical archives as these
parts of the river area are seldom inhabited [61].
The cartographic archives, along with historical information on navigation structures, can be used to reconstruct their history. Figure 9 shows the modifications of
the river channel in the Poses sector (for location, see Fig. 1), which marks today’s
upper limit of the tidal influence, between 1846 (Ponts et chaussées map) and 2015
(IGN map).
50
L. Lestel et al.