Programme  OS1h Multi-stakeholders and institutions for IWRM  abstract 176

Modelling regional water demand for agriculture with stakeholders : an example in the Drôme basin.

Author(s): Ph. Le Grusse, J.C. Poussin, P. Ruelle, M. Le Bars, L. Brunel, J.M Gonzalès-Camacho, J.C. Mailhol, J. Granier
UMR G-eau

Keyword(s): integrated management, agricultural water demand, participative modelling, regional model

Article: abs176_article.pdf
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Session: OS1h Multi-stakeholders and institutions for IWRM
AbstractThe “integrated management of water resources” tries to

convey the functioning of the “hydro-systems” which brings together a group of resources and uses of water. This

group of resources and uses interacts within a territory, which itself includes various administrative or political units.

In order to develop this integrated management, some countries have chosen decentralization: water management is

then given to basin institutions within which representatives of the various key interests sit. These institutions

emphasize the poor support they get to encourage the dialogue. Available tools emphasize biophysical process but

provide a very simplified representation of uses, and particularly of farm uses. These uses are not only linked to

water availabilities and to its conditions of access, but also to the technological, economic, and institutional

background in which the farmers operate.

With the local stakeholders, we suggest to build a model of the

system in which they act. At the same time, this model includes the technical, economic, and environmental sides.

Therefore, this regional model includes (i) a hydrological model, which enables to assess as input the initial resource

availabilities and to measure the impacts of withdrawals, (ii) a biophysical model which enables to assess crop water

needs, yields and environmental impacts according to agricultural practices and agro-climatic conditions, and (iii) a

technical and economic model which conveys the technical choices of farmers and theirs economic consequences.

The construction of the hydrological and biophysical models can be limited to the parameterization of pre-existing

models. The technical and economic model of farm activities at the regional scale relies on a typology of farms and of

farm production units; its structure has been designed to enable an aggregation and a desegregation of the results

between various scales, which provides a detailed analysis of the studied scenarios.

The participative

construction of the regional model relies on the creation, from the start of the study, of a “steering group” compound

of the representatives of local stakeholders. This steering group takes part in the modelling by supplying the

necessary data and by validating each stage of the model construction. The model, build and validated by all the

stakeholders, can then contribute to help the local or regional decision-makers to develop reasoned scenarios in

order to define strategies of integrated and sustainable water management.

We have implemented this

approach in the Drôme basin within the framework of the APPEAU project funded by the "Agriculture et

Développement Durable" program of the French National Research Agency, and by relying on the works of the

MIPAIS project funded by the Programme Interreg III Medoc of the European Union. This paper presents the first

results obtained.

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