selected major elements (e.g. nitrogen). The opening of the biogeochemical cycles
due to multiple factors has led to more systemic approaches combining the following
trajectory components: (1) state indicators; (2) controlling factors and pressures
indicators, generally economic; and (3) a set of social indicators, such as scientific
knowledge and social awareness, inclusion of issues on the political agenda, environmental surveys, as well as regulatory and technical responses.
This work is complex, since both water and river systems are at the same time a
resource, an economic good, and a cultural and symbolic asset, subject to different
regulations according to these various functions. Each function generates specific
actors or sets of actors and is perceived differently by each of these actors according
to the numerous and variable reading grids over time.
3.1 Circulation of Material Within the Basin
The main advantage of river systems is the possibility to carry out material balances
by monitoring material fluxes at the outlet of the basin. This approach provides
integrated information for the entire territory of the basin and its population, at
various time steps. Deciphering all the complexity and heterogeneity of the multiple
fluxes requires specific studies for the past and present situations. For almost
30 years, river systems have been recognized for this complexity and studied in an
interdisciplinary way owing to it, such as in the PIREN-Seine programme since 1989
or in other programmes [51].
For geologists and geochemists, natural material fluxes within river basin fluxes
are derived from the erosion and weathering products of surficial rocks and from the
uptake of atmospheric carbon and nitrogen occurring within the basin. For environmental chemists, the river-borne material contamination results from waste discharges and runoff and from the erosion of soils contaminated by diffuse sources.
For environmental economists, material flow analysis over a given territory reveals
the metabolism of the anthroposphere, the storage of left-over products, the growing
pattern of infrastructures, and the recycling of products and goods [16]. The comparison of additional river fluxes – compared with estimated natural material fluxes –
reveals that the circulation of many economic products used in the Seine River basin
is between one and two orders of magnitude greater than the natural material fluxes,
as for the heavy metals [52]. This new view of territorial functioning is schematized
in Fig. 5, in which the system is described by a set of natural and/or anthropogenic
reservoirs between which there is a continuous circulation.
The river receives a share – between 0.1 and 40% depending on products and
periods – of this economic circulation (e.g. 0.1% for metals [55], 7% for phosphorus
[56], and 40% for nitrate [57]). The specific circulations and their impacts on river
exports vary over time and may relate to different locations in a river basin (see
Fig. 6 for metals).
The reconstruction of these fluxes and of their evolution over time makes it
necessary to correlate the knowledge on the circulation of substances in the
anthroposphere (manufacturing, importation, consumption, and evolution of uses)
Trajectories of the Seine River Basin
11
due to multiple factors has led to more systemic approaches combining the following
trajectory components: (1) state indicators; (2) controlling factors and pressures
indicators, generally economic; and (3) a set of social indicators, such as scientific
knowledge and social awareness, inclusion of issues on the political agenda, environmental surveys, as well as regulatory and technical responses.
This work is complex, since both water and river systems are at the same time a
resource, an economic good, and a cultural and symbolic asset, subject to different
regulations according to these various functions. Each function generates specific
actors or sets of actors and is perceived differently by each of these actors according
to the numerous and variable reading grids over time.
3.1 Circulation of Material Within the Basin
The main advantage of river systems is the possibility to carry out material balances
by monitoring material fluxes at the outlet of the basin. This approach provides
integrated information for the entire territory of the basin and its population, at
various time steps. Deciphering all the complexity and heterogeneity of the multiple
fluxes requires specific studies for the past and present situations. For almost
30 years, river systems have been recognized for this complexity and studied in an
interdisciplinary way owing to it, such as in the PIREN-Seine programme since 1989
or in other programmes [51].
For geologists and geochemists, natural material fluxes within river basin fluxes
are derived from the erosion and weathering products of surficial rocks and from the
uptake of atmospheric carbon and nitrogen occurring within the basin. For environmental chemists, the river-borne material contamination results from waste discharges and runoff and from the erosion of soils contaminated by diffuse sources.
For environmental economists, material flow analysis over a given territory reveals
the metabolism of the anthroposphere, the storage of left-over products, the growing
pattern of infrastructures, and the recycling of products and goods [16]. The comparison of additional river fluxes – compared with estimated natural material fluxes –
reveals that the circulation of many economic products used in the Seine River basin
is between one and two orders of magnitude greater than the natural material fluxes,
as for the heavy metals [52]. This new view of territorial functioning is schematized
in Fig. 5, in which the system is described by a set of natural and/or anthropogenic
reservoirs between which there is a continuous circulation.
The river receives a share – between 0.1 and 40% depending on products and
periods – of this economic circulation (e.g. 0.1% for metals [55], 7% for phosphorus
[56], and 40% for nitrate [57]). The specific circulations and their impacts on river
exports vary over time and may relate to different locations in a river basin (see
Fig. 6 for metals).
The reconstruction of these fluxes and of their evolution over time makes it
necessary to correlate the knowledge on the circulation of substances in the
anthroposphere (manufacturing, importation, consumption, and evolution of uses)
Trajectories of the Seine River Basin
11