IWRA World Water Congress 2008 Montpellier France
1. Water availability, use and management
Ph. Le Grusse
M. Le Bars
integrated management, agricultural water demand, participative modelling, regional model
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.
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