Assessing the irrigation strategies over a wide geographical area from structural data about farming systems

Accurate estimation of regional water demand - by agriculture, mainly consumed by farmers for irrigation, is a key requirement for water management. It depends on the farmers' irrigation practices which itself depend on the farmers' irrigation strategies.' Describing irrigation strategies over a region is rather difficult due to the large number and the diversity of farmers. We seek whether it,is possible to:characterise irrigation strategies from easily. accessible farm characteristics data at,the regional scale. For that purpose, we investigated the relationships between maize irrigation strategies, and three farming sub-systems: the production system, the water resource system and the irrigation equipment system. Based on a 56-farmers survey of maize irrigation strategies carried. Put in twos different areas in south-western France, we firstly created typologies from the three farming sub-systems and from irrigation strategies and, in a second step, analysed,the links between the different typologies. Multivariate analyses, cluster analyses, linear regressions and regression, tree were used for that purpose. Only two types of irrigation strategies were found that could not be fully explained by the three sub-system typologie. However, the theoretical irrigation capacity explains a part of the irrigation strategies. Such data can be obtained, at a wide geographical scale from administrative data bases. Strategic management of irrigation is similar amongst farmers in a given area while more operational actions differ from farmer to farmer. Standardisation of strategies due to county-based advice is then discussed. (c) 2004 Elsevier Ltd. All rights reserved.