First, the Centenario sub-basin, whose surface area extends mainly to the north of the Project area, and secondly, the Ratones sub-basin, to the south; both are made up of ephemeral fluvial streams that never reach the salars due to the extreme aridity of the climate and the high permeability of the alluvial fans.The physical separation of the Centenario and Ratones basins is materialised by the Vicuña Muerta river, at the distal end of which the river has built a dilated cone that causes the salt flats to separate on the surface.