3.4 Models Enable Exploration of Socio-hydrosystem
Scenarios and Their Consequences
Models have been spatially extended and gradually developed to incorporate more
processes and interactions. On the basis of an analysis of trajectories of the major
feature in the Seine basin, Riverstrahler made it possible to reconstitute the past
evolution of water quality in the drainage network. A further useful feature of models
is the exploration of the future of the hydro-socio-system through scenarios of
sectorial changes in combination (or not) with climate change scenarios and simulation of the related river response [26]. These scenarios may simulate ‘business as
usual’ (same trends in control factors), stepwise gradual changes or drastic changes
(‘what if’ scenarios), which generate different sets of spatialized results on river
state.
The model can be operated to feed scenarios, or the scenarios provide a new set of
controlling parameters to the model and input data set. Two major approaches have
been applied: (1) The preventive approach explores the possible changes in pressures
on the basin, e.g. diffuse sources from agriculture; and (2) the curative approach tests
the impact of river remediation measures.
3.4.1 Preventive Approach: Simulation of Agricultural Changes
in the Seine Basin
PIREN-Seine scientists have explored the transition from a conventional intensive
cropping system, which has dominated in the basin for several decades, to generalized organic production in response to new food demand for a ‘demitarian’ diet
(reduction by half of animal product consumption). The impact of this new type of
agriculture is based on an experimental agronomic field study with a set of farmers
changing their agricultural practices (for more details, see Sect. 4.1). The nitrogen
fluxes in soils and unsaturated areas were measured in a dozen farms over 3–6 years.
These results were then incorporated in the models and upscaled to the whole basin.
A realistic scenario of a deep structural agricultural change that is autonomous and
organic, with a reconnection of crop, livestock and a demitarian diet, has been
elaborated at the scale of the Seine basin and compared with a scenario based on
good agricultural practices (see Box 5).
Box 5
Models to explore river responses to agricultural scenarios and territorial
management in the Seine basin.
‘We have named “territorial biogeochemistry”, the branch of science that
describes and tries to understand the functioning of such complex systems,
(continued)
398
C. Carré et al.
Scenarios and Their Consequences
Models have been spatially extended and gradually developed to incorporate more
processes and interactions. On the basis of an analysis of trajectories of the major
feature in the Seine basin, Riverstrahler made it possible to reconstitute the past
evolution of water quality in the drainage network. A further useful feature of models
is the exploration of the future of the hydro-socio-system through scenarios of
sectorial changes in combination (or not) with climate change scenarios and simulation of the related river response [26]. These scenarios may simulate ‘business as
usual’ (same trends in control factors), stepwise gradual changes or drastic changes
(‘what if’ scenarios), which generate different sets of spatialized results on river
state.
The model can be operated to feed scenarios, or the scenarios provide a new set of
controlling parameters to the model and input data set. Two major approaches have
been applied: (1) The preventive approach explores the possible changes in pressures
on the basin, e.g. diffuse sources from agriculture; and (2) the curative approach tests
the impact of river remediation measures.
3.4.1 Preventive Approach: Simulation of Agricultural Changes
in the Seine Basin
PIREN-Seine scientists have explored the transition from a conventional intensive
cropping system, which has dominated in the basin for several decades, to generalized organic production in response to new food demand for a ‘demitarian’ diet
(reduction by half of animal product consumption). The impact of this new type of
agriculture is based on an experimental agronomic field study with a set of farmers
changing their agricultural practices (for more details, see Sect. 4.1). The nitrogen
fluxes in soils and unsaturated areas were measured in a dozen farms over 3–6 years.
These results were then incorporated in the models and upscaled to the whole basin.
A realistic scenario of a deep structural agricultural change that is autonomous and
organic, with a reconnection of crop, livestock and a demitarian diet, has been
elaborated at the scale of the Seine basin and compared with a scenario based on
good agricultural practices (see Box 5).
Box 5
Models to explore river responses to agricultural scenarios and territorial
management in the Seine basin.
‘We have named “territorial biogeochemistry”, the branch of science that
describes and tries to understand the functioning of such complex systems,
(continued)
398
C. Carré et al.