drain ditch in the field
interception drain ditch
weeper drain；weep drain；drainage ditch；drain ditch
Double channel ditch (W-type ditch)
drain castinghollow casting drain tile
agricultural drainage ditch
airlift oxidation ditch
alternating triple oxidation ditch
ameliorated triple oxidation ditch
an integrated oxidation ditch
Carrousel 2000 Oxidation Ditch