Résumé : The Coquimbo region, in Chile, receives a rainfall of 110mm (annual mean), winter rains, which allow only small scale cereal cropping and pastures for goat and sheep raising. However, thanks to subtle irrigation processes, practiced for centuries, the region used to export high value agricultural products up to mining and transportation workers and facilities settled in the northern arid area of the country. The history of ground occupation and soil uses, throughout the colonial era then in an independent Chile, designed not only the land property modalities, but also the sharing of rights of water usage. During the last sixty years, this system has changed considerably, with both technical causes (artificial lakes to stock water, cheap electric energy in rural areas) and with political and social causes (agrarian reform, agricultural foreign capital). The scientific research program “
Suivi de la désertification, connaissance des systèmes d’élevage caprin, gestion de la ressource en eau : trois aspects pour la définition d’une politique environnementale incluant la participation des populations dans la IV
région du Chili (ECOS-Conicyt)” studied theses changes and their consequences, in order to anticipate consequences and foresee negative ones: the “Limarí model” is frequently given as an example of successful economic development and is to be copied in other arid valleys. The irrigation graphic scheme of the valley of Limarí is hereafter presented in four dynamic figures, as one of the multidisciplinary supports for research into the well-known problems of geographic and economic balance between rural and urban development, between irrigated and arid areas, and upon the long range effects of the disconnection between land rights and water rights. The new social and economic order will be effected as a consequence of the relationship between new technical applications and new laws and rights. This graphic demonstration is contrived to organise and discuss available information about water, energy, irrigated areas and regulation by law.