The paper deals with the irrigation and drainage systems used for land reclamation in a tertiary sedimentation basin in Spain in which the Ebro River and its tributaries have incised alluvial valleys. Subjects discussed cover characteristics of the area hydrology, soils and soil conditions, soil salinity, drainage and land reclamation experimental fields, derivation of drainage equations of agro-hydrological factors, desalination processes, and subsurface drainage system.