the cumulated natural and man-made transformations that have shaped the territory:
any map reflects heritages of past dynamics.
Many natural (Table 1, A–E) and man-made (F–Q) elements were represented
for navigation purposes, river network (A1) (see Fig. 4a) and navigation channel (I)
(Fig. 4b, c, e), river depth (C) and topographic profiles (K) (Fig. 4d), obstacles (B, D,
Fig. 4c), harbours (G) and locks (J) (Fig. 4e), or for river regulation, dams (L) or
flooded area (A2). Other maps show places where energy is produced (water mills,
F) or ponds (Q) and starting areas for timber rafting (H) (Fig. 4a), elements related
to agriculture (ditches on very-fine-scale maps (P), Fig. 5) and food production
(fisheries, N, Fig. 4b).
The physical river state and dynamics can be studied on numerous elements:
identification of channel type and pattern from the presence and shape of the islands
[4], modified flows (watermill derivations on a lateral canal (0.1–1 km) while
the main river course is left active only at high flows) and changes in river regime
by dams and weirs; dredging area (navigation channel and ports); loss of lateral
connectivity due to the artificialisation of the banks and raising them to create
towpaths; modified groundwater/surface water exchanges due to the change in
the river’s water level (dams and weirs) and to the presence of gravel pits (O);
bank erosion in timber rafting reaches [24]; and sediment trapping within reservoirs
(L), disconnection of lateral channels (E), delineation of flooded areas (A2) and
ponds (Q).
The ecological state of the river can be addressed particularly through its
fish habitats. Presence of islands (D), disconnected lateral channels and oxbows
(E) provides potential refuges, spawning grounds and feeding grounds for fish
[2]. The deepening of the river and the bank re-profiling seen on bathymetric maps
(C) (e.g. Vuillaume, Fig. 4e) result in the loss of fish habitat areas and diversity.
Dams (L), water mills (F) and weirs (J) are obstacles to fish migration. In the 1890s,
weirs on the Lower Seine (Fig. 4d, e) were equipped with fish ladders, but they were
not sufficiently effective to allow salmon, once common in the Seine basin [50, 51],
to reach their spawning grounds 400 km upstream in the basin headwaters. The
connectivity and the ecology of fluvial wetlands are also affected by river works,
mainly dikes and levees (I) and more recently by sandpits.
The socio-economic uses of the river, the potential water conflicts and the flood
risks can be analysed from river maps: the river network (A1) shows where to access
surface water resources; water mills (F) mark where river power was used and
potential water conflicts; navigation and river access are facilitated by river works;
but new reservoirs (L) or erosion areas (H) result in loss of property. In contrast, river
channeling (I) and the related disconnection/filling of backwater wetlands lead to a
possible gain of property for the riparian landowners. Dikes and levees (I) were
considered until recently as effective protection against flooding, leading to economic development close to the river. This positive “levee effect” ([48], Cited by
[49]) is now being revised [49, 52, 53] because, although dikes prevent the natural
inundation of the floodplain, they also limit the water storage at high flows and
therefore increase the flood risk for downstream settlements.
Finally, some chemical effects on rivers can be related to fluvial elements
represented on maps. Water mills (F), dams (L) and weirs (J) have downstream
44
L. Lestel et al.
any map reflects heritages of past dynamics.
Many natural (Table 1, A–E) and man-made (F–Q) elements were represented
for navigation purposes, river network (A1) (see Fig. 4a) and navigation channel (I)
(Fig. 4b, c, e), river depth (C) and topographic profiles (K) (Fig. 4d), obstacles (B, D,
Fig. 4c), harbours (G) and locks (J) (Fig. 4e), or for river regulation, dams (L) or
flooded area (A2). Other maps show places where energy is produced (water mills,
F) or ponds (Q) and starting areas for timber rafting (H) (Fig. 4a), elements related
to agriculture (ditches on very-fine-scale maps (P), Fig. 5) and food production
(fisheries, N, Fig. 4b).
The physical river state and dynamics can be studied on numerous elements:
identification of channel type and pattern from the presence and shape of the islands
[4], modified flows (watermill derivations on a lateral canal (0.1–1 km) while
the main river course is left active only at high flows) and changes in river regime
by dams and weirs; dredging area (navigation channel and ports); loss of lateral
connectivity due to the artificialisation of the banks and raising them to create
towpaths; modified groundwater/surface water exchanges due to the change in
the river’s water level (dams and weirs) and to the presence of gravel pits (O);
bank erosion in timber rafting reaches [24]; and sediment trapping within reservoirs
(L), disconnection of lateral channels (E), delineation of flooded areas (A2) and
ponds (Q).
The ecological state of the river can be addressed particularly through its
fish habitats. Presence of islands (D), disconnected lateral channels and oxbows
(E) provides potential refuges, spawning grounds and feeding grounds for fish
[2]. The deepening of the river and the bank re-profiling seen on bathymetric maps
(C) (e.g. Vuillaume, Fig. 4e) result in the loss of fish habitat areas and diversity.
Dams (L), water mills (F) and weirs (J) are obstacles to fish migration. In the 1890s,
weirs on the Lower Seine (Fig. 4d, e) were equipped with fish ladders, but they were
not sufficiently effective to allow salmon, once common in the Seine basin [50, 51],
to reach their spawning grounds 400 km upstream in the basin headwaters. The
connectivity and the ecology of fluvial wetlands are also affected by river works,
mainly dikes and levees (I) and more recently by sandpits.
The socio-economic uses of the river, the potential water conflicts and the flood
risks can be analysed from river maps: the river network (A1) shows where to access
surface water resources; water mills (F) mark where river power was used and
potential water conflicts; navigation and river access are facilitated by river works;
but new reservoirs (L) or erosion areas (H) result in loss of property. In contrast, river
channeling (I) and the related disconnection/filling of backwater wetlands lead to a
possible gain of property for the riparian landowners. Dikes and levees (I) were
considered until recently as effective protection against flooding, leading to economic development close to the river. This positive “levee effect” ([48], Cited by
[49]) is now being revised [49, 52, 53] because, although dikes prevent the natural
inundation of the floodplain, they also limit the water storage at high flows and
therefore increase the flood risk for downstream settlements.
Finally, some chemical effects on rivers can be related to fluvial elements
represented on maps. Water mills (F), dams (L) and weirs (J) have downstream
44
L. Lestel et al.