1 Introduction
Given that it deeply affects the functioning of terrestrial ecosystems, agriculture is
not only the major determinant of landscape structure, biodiversity and soil biogeochemistry but also an essential factor in determining the hydrology and water quality
of river systems and their receiving marine coastal waters. In particular, the nutrient
(C, N, P, Si) composition of ground- and surface water is largely dependent on
diffuse sources from the watershed which respond to land use and agricultural
practices. This response, however, is far from being simple and direct, due to the
complex cascade of processes, including storage and elimination, that nutrients,
emitted from the root zone of cropping systems, have to move across, with temporalities ranging from sub-hourly to multi-decadal.
The Seine watershed, with a catchment area of about 70,000 km
2 , is entirely
located within one of the most fertile areas of Western Europe, the Paris Basin. This
geological unit consists of concentric tertiary sedimentary formations (alternating
clay, sandstone and limestone), covered by loess in its central part and lying on a
basement of ancient crystalline rock formations outcropping at the extreme SouthEast and North-East (Fig. 1a). Paris developed in the middle of the drainage network,
at the convergence area of large tributaries draining this basin, which historically was
a favourable factor in terms of the city’s food, feed and fuel supply. Currently, the
central zone of the Seine watershed, around the huge Paris conurbation, is oriented
towards mass production of cereals and industrial crops, while animal breeding is
restricted to the peripheral areas of the basin where pedoclimatic conditions are less
suitable to stockless cropping systems (Fig. 1b).
The Seine River basin has been subject to intensive research for 30 years within
the PIREN-Seine programme [2, 3]. Here we present a synthesis of this work,
addressing the interrelated issues of agricultural dynamics, soil biogeochemistry
as well as ground- and surface water nutrient contamination. The purpose of this
chapter is to describe, over a 150-year period, the long-term dynamics through which
the current state of the agricultural system has gradually been constructed, in order to
understand both the drivers of change and the inertia of the different environmental
compartments of the water-agro-food system of the Seine watershed. Based on
this long-term view of the role of legacies on the current system functioning, the
issue of its possible future evolution will be shortly addressed.
2 Material and Methods
This chapter is mainly based on the results of two complementary integrated research
efforts developed in the PIREN-Seine programme (www.piren-seine.fr), namely, the
GRAFS-Riverstrahler and the ARSeine-STICS-MODCOU approaches, which are
here compared and merged for the very first time. These two approaches differ
in their level of detail, time and space resolution and the duration of the historical
period they are able to encompass.
The Seine Watershed Water-Agro-Food System: Long-Term Trajectories of C. . .
93
Given that it deeply affects the functioning of terrestrial ecosystems, agriculture is
not only the major determinant of landscape structure, biodiversity and soil biogeochemistry but also an essential factor in determining the hydrology and water quality
of river systems and their receiving marine coastal waters. In particular, the nutrient
(C, N, P, Si) composition of ground- and surface water is largely dependent on
diffuse sources from the watershed which respond to land use and agricultural
practices. This response, however, is far from being simple and direct, due to the
complex cascade of processes, including storage and elimination, that nutrients,
emitted from the root zone of cropping systems, have to move across, with temporalities ranging from sub-hourly to multi-decadal.
The Seine watershed, with a catchment area of about 70,000 km
2 , is entirely
located within one of the most fertile areas of Western Europe, the Paris Basin. This
geological unit consists of concentric tertiary sedimentary formations (alternating
clay, sandstone and limestone), covered by loess in its central part and lying on a
basement of ancient crystalline rock formations outcropping at the extreme SouthEast and North-East (Fig. 1a). Paris developed in the middle of the drainage network,
at the convergence area of large tributaries draining this basin, which historically was
a favourable factor in terms of the city’s food, feed and fuel supply. Currently, the
central zone of the Seine watershed, around the huge Paris conurbation, is oriented
towards mass production of cereals and industrial crops, while animal breeding is
restricted to the peripheral areas of the basin where pedoclimatic conditions are less
suitable to stockless cropping systems (Fig. 1b).
The Seine River basin has been subject to intensive research for 30 years within
the PIREN-Seine programme [2, 3]. Here we present a synthesis of this work,
addressing the interrelated issues of agricultural dynamics, soil biogeochemistry
as well as ground- and surface water nutrient contamination. The purpose of this
chapter is to describe, over a 150-year period, the long-term dynamics through which
the current state of the agricultural system has gradually been constructed, in order to
understand both the drivers of change and the inertia of the different environmental
compartments of the water-agro-food system of the Seine watershed. Based on
this long-term view of the role of legacies on the current system functioning, the
issue of its possible future evolution will be shortly addressed.
2 Material and Methods
This chapter is mainly based on the results of two complementary integrated research
efforts developed in the PIREN-Seine programme (www.piren-seine.fr), namely, the
GRAFS-Riverstrahler and the ARSeine-STICS-MODCOU approaches, which are
here compared and merged for the very first time. These two approaches differ
in their level of detail, time and space resolution and the duration of the historical
period they are able to encompass.
The Seine Watershed Water-Agro-Food System: Long-Term Trajectories of C. . .
93