**A perforated pipe with many rectangular slots has better drainage characteristics than a pipe with similar open area provided by fewer circular holes <ref>Hazenberg, G., and U. S. Panu (1991), Theoretical analysis of flow rate into perforated drain tubes, Water Resour. Res., 27(7), 1411–1418, doi:10.1029/91WR00779.</ref>. | **A perforated pipe with many rectangular slots has better drainage characteristics than a pipe with similar open area provided by fewer circular holes <ref>Hazenberg, G., and U. S. Panu (1991), Theoretical analysis of flow rate into perforated drain tubes, Water Resour. Res., 27(7), 1411–1418, doi:10.1029/91WR00779.</ref>. |