The Vallerani system: a technology specially conceived for fighting against desertification, hunger and poverty (protection of bio-diversity, control of the climatic changes and sustainable development) through soil and water conservation, afforestation and increase of the agricultural production in the arid and semi-arid regions

captage d'eau conservation de la nature conservation des sols desertification escorrentia fertilidad del suelo gestion des eaux gestion du sol manejo del suelo nature conservation ruissellement runoff soil soil conservation soil fertility soil management soil water retention sol suelo technologie technology tecnologia water harvesting water management