• Aucun résultat trouvé

en fr

N/A
N/A
Protected

Academic year: 2022

Partager "en fr "

Copied!
2
0
0

Texte intégral

(1)

HAL Id: hal-02593814

https://hal.inrae.fr/hal-02593814

Submitted on 15 May 2020

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

SSA 10 Pertuis charentais: Freshwater allocation in the Charente river catchment

Jean Prou, C. Bacher, J. Ballé Béganton, R. Mongruel, J.A. Pérez Agúndez, Françoise Vernier, Pierre Bordenave, Jacqueline Candau, François Delmas, Y.

Mensencal, et al.

To cite this version:

Jean Prou, C. Bacher, J. Ballé Béganton, R. Mongruel, J.A. Pérez Agúndez, et al.. SSA 10 Per-

tuis charentais: Freshwater allocation in the Charente river catchment. Spicosa meeting, Feb 2010,

Istanbul, Turkey. pp.1, 2010. �hal-02593814�

(2)

Standing stock

Year 1 Year 6

Model spin up Marketable stock

Grade 2 to 4

Harvest Standing stock

Year 1 Year 6

Model spin up Marketable stock

Grade 2 to 4

Harvest

2. Policy issue 1. Map of the site and the virtual system

SSA 10 Pertuis charentais

Freshwater allocation in the Charente river catchment

SSA 10 Pertuis charentais

Freshwater allocation in the Charente river catchment

1Ifremer, Environment and Resource Laboratory of Poitou Charente,

2Ifremer, UMR Amure, Marine Economics Departement

3Ifremer, Coastal System Dynamics Department

4Cemagref Cestas, ADER Unit

5SOGREAH –6EPTB Charente –7Eaucéa

7. Simulation results: oyster production

The policy issue concerns the quantitative management of the freshwater in the Charente river basin. This problem has been addressed by the regional plan for water management (SDAGE), which includes a “Water shortage Management Plan” (PGE) dedicated to the Charente river.

The SDAGE and the PGE have fixed the following:

- the hierarchy of the freshwater uses= 1) good ecological status of the coastal ecosystems 2) drinking water for households 3) other uses: agriculture, shellfish farming…

-Reachable Discharge Thresholds(RDT) at different control points, which are supposed to be sufficient to ensure the 2 first uses; the general objective of this management plan will be to make sure that the system is able to reach the RDTs during the summer at least 8/10 years.

The current debate aims at modifying the “authorised volumes of water” for each uses(consumptive uses: drinking water, irrigation) and improving the restriction rules.

Contact us: Jean.Prou@ifremer.fr, Remi.Mongruel@ifremer.fr&Francoise.Vernier@cemagref.fr

3. Extend simulation platform 4. Model calibration

The blocks and modules are organised in a user-friendly way. Graphical tools improve the visualisation of relevant indicators. Scenario, display and output blocks have been set to regroup all the model control panels.

Each module is linked to a corresponding database that records all model parameters and state variables. The model has been developped usingHierarchical and Custom blocks in ExtendSim ModL language.

5. Internal feedback loops 6. Innovative socio-economic component:

ecosystem services economic assessment

8. Participant Group

GovernanceandRegulationsystem Humanactivities(wateruses) Physicalandecologicalsystem

Jean Prou1, Cédric Bacher3, Johanna Ballé-Béganton2, Rémi Mongruel2, José A. Pérez Agúndez2,

Françoise Vernier4, Paul Bordenave4, Jacqueline Candau4, François Delmas4, Yvon Mensencal5, Harold Réthoret6 and Julien Neveu7

The above schematic presents the internal feedback loop which brings together the irrigation practices of farmers, their impacts on the river flow and the possible enforcement of irrigation restriction measures. After those measures have been implemented, irrigation is constrained and the water flow at monitoring station may increase again, leading to the suspension of the restriction measures.

At a wider scale, the system encompasses feedback loops which link the evolution of water uses and the inter-annual negotiation of the regulation framework. However, such policy changes are considered through scenarios.

The links between fresh water availability, coastal productivity and shellfish farming production are explored by the model.

Outputs of the shellfish farming sub-model estimate additional costs(benefits) associated with the productivity losses (gains) due to freshwater relative scarcity, which depends on climatic changes and the joint evolution of rival anthropogenic uses.

According to the representation of the system which has been agreed upon by the participant group, the freshwater of the Charente river provides mainly “support services” for natural habitats and shellfish farming and “provisioning services” for households and agriculture.

The economic assessment of the ecosystem services will be based on the damage costs assessment method (costs of avoided damages, productivity losses and remediation costs).

irrigation

«Charente » river flow

water flow at monitoring

stations

crisis irrigation restriction

coastal productivity

oyster growth

pluriannual irrigation restriction

Scenarios

-

-

+

-

+ +

- + Internal

Feedback Loop

- Hydrological system

Upstream activities Drinking water (households &

tourists) Water demand for crops

Governance system Stakeholders deliberations

Water management (T=inter-annual) Water shortage regulation (T=crisis)

Ecosystems

Downstream activities

Drinking water (households; tourists) Shellfish farming Agriculture on the wetlands Recreational activities Coastal waters (salinity)

Biodiversity : species and livelihoods, incl. wetlands Input = River alimentation Output = Water discharge at control point

Social demand for water Social demand for

water

Access regulation Hydrological settlements [Scenarios]

Support services Provisioning

services

Support services

Access regulatio n

Boundaries of the system for the formulation step Rules in use Scenarios SPICOSA Forum

Provisioning services

Support services

Freshwater services

Ecosystem services

Damage costs assessment

Provisioning services

Principles and methodology

Drinking water Agriculture (irrigated crops) Shellfish

farming Support services

Biodiversity (river fauna)

Costs of avoided damages

Remediation costs Productivity losses

Expenses for safeguarding fishing

Additional production costs

Market value of

"lost production"

Public expenses Productivity

losses

Model calibration is illustrated with the hydrological module.

The Hydrological module is adapted from an existing model (CycleauPE) and translated into the ExendSim modelling platform. Model outputs are tested with several input data sets (rain, evapotranspiration) and simulated riverflows are compared to the results of the original model.

The other modules (Hydrology, Coastal Productivity, Agriculture, Shellfish Farming) are also tested independently using existing datasets or outputs from existing models.

Example of the riverflow of watershed simulated during one year (blue) and comparison with the CycleauPE simulation (green).

The participant group (PG) of the SSA consists in regular de visumeetings between 6 local managersand a sub-group of 3 researchers from the SSA team. Each meeting is observed by a social scientist in order to analyse the exchanges between the managers and the researchers.

Recent meetings of the PG were dedicated to the building of scenarios, following a deliberation methodology based on transparent votes(work in progress). In a first step, the PG produced a list of 50 assumptions regarding the future of the system in three domains: trends (climate, demography), management options and changes in uses and practices. In a second step, the stakeholders voted on these assumptions in order to sort a hierarchy. In a third step, stakeholders will be asked to vote on combinations of assumptions using the deliberation matrix(in order to build complete scenarios).

Besides the existing decision support tools that they already use, the stakeholders expect from the SPICOSA experiment a scientific exploration of the complex and dynamic relationships between the three dimensions (ecology-economy-society) of the freshwater allocation problem.

Références

Documents relatifs

Net-present value approach to determine yearly cash flows Reflecting on farmers’ performance: High costs vs.

To sum up, we have pointed out that Gibbs, among others, gives the strong impression that metaphors are not costly. We were skeptical of this claim, especially if the implication

While the technical potential exists, there are, at the current costs of alternatives, questions about the economic potential (ibid.: 637). The economic costs of leveraging

The lower blue line shows the residual load that needs to be covered by conventional power producers (white area). All power generation technologies cause system effects. By virtue

More recently, another study showed that with/without opportunity costs of grain legumes were slightly positive, while those of forage legumes were zero or even negative, with a

• Negative relationships between reproduction and subsequent vegetative growth at different levels in the mango tree. • Cultivar effect on

[r]

We specify a cost function with four outputs (long and short-tail personal, long and short-tail commercial), one output quality variable (reinsurance as measured by ceded