built drainage system Collection of open and/or closed drains, together with structures and pumps used to collect and dispose of excess surface or subsurface water
drainage system A surface stream, or a body of impounded surface water, together with all other such streams and water bodies that are tributary to it and by which a region is drained. An artificial drainage system includes also surface and subsurface conduits
subsoil drainageThe removal of surplus water from within the soil by natural or artificial means, such as by drains placed below the surface to lower the water table below the root zone