| Whilst it is recognised that many smaller perforations present a greater resistance to flow than fewer, larger perforations<ref>Pabst, M., & France, J. (n.d.). GETTING WATER INTO PIPES -NOT AS EASY AS IT SEEMS. Retrieved from http://dnrc.mt.gov/divisions/water/operations/docs/dam-safety/technical-references/getting_water_into_pipes.pdf</ref>, calibrating for this is quite complex <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><ref>Murphy, P. (n.d.). THE HYDRAULIC PERFORMANCE OF PERFORATED PIPE UNDER-DRAINS SURROUNDED BY LOOSE AGGREGATE. Retrieved from http://tigerprints.clemson.edu/all_theses</ref>. The practice of approximating, using the open area of the pipe per unit length, is commonplace, and we are unaware of ill effects arising<ref>Department of Planning and Local Government South Australia. (2010). Water Sensitive Urban Design Technical Manual Greater Adelaide Region Bioretention Systems for Streetscapes. Adelaide. Retrieved from https://www.sa.gov.au/__data/assets/pdf_file/0010/19837/WSUD_chapter_10.pdf</ref><ref>ADS pipe. (2004). Outflow from Perforated Pipe. Retrieved March 12, 2018, from http://discountdrainage.com/dev/wp-content/uploads/Technical_Note_2.105_Outflow_From_Perforated_Pipe.pdf</ref><ref>Titan Industries Inc. (n.d.). To Calculate the Amount of Water Flow (GPM) Through Slotted PVC Well Screen. Retrieved from http://www.titanpipe.com/Engineering_Titan_Industries_In/Water Flow PVC Well Screen.pdf</ref><ref>WaveRail. (n.d.). WATER WELL SCREEN & CASING SYSTEMS. Retrieved March 12, 2018, from http://www.waverail.nl/images/Template_content/PDF/documentatie/Filter-buizen.pdf</ref>. | | Whilst it is recognised that many smaller perforations present a greater resistance to flow than fewer, larger perforations<ref>Pabst, M., & France, J. (n.d.). GETTING WATER INTO PIPES -NOT AS EASY AS IT SEEMS. Retrieved from http://dnrc.mt.gov/divisions/water/operations/docs/dam-safety/technical-references/getting_water_into_pipes.pdf</ref>, calibrating for this is quite complex <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><ref>Murphy, P. (n.d.). THE HYDRAULIC PERFORMANCE OF PERFORATED PIPE UNDER-DRAINS SURROUNDED BY LOOSE AGGREGATE. Retrieved from http://tigerprints.clemson.edu/all_theses</ref>. The practice of approximating, using the open area of the pipe per unit length, is commonplace, and we are unaware of ill effects arising<ref>Department of Planning and Local Government South Australia. (2010). Water Sensitive Urban Design Technical Manual Greater Adelaide Region Bioretention Systems for Streetscapes. Adelaide. Retrieved from https://www.sa.gov.au/__data/assets/pdf_file/0010/19837/WSUD_chapter_10.pdf</ref><ref>ADS pipe. (2004). Outflow from Perforated Pipe. Retrieved March 12, 2018, from http://discountdrainage.com/dev/wp-content/uploads/Technical_Note_2.105_Outflow_From_Perforated_Pipe.pdf</ref><ref>Titan Industries Inc. (n.d.). To Calculate the Amount of Water Flow (GPM) Through Slotted PVC Well Screen. Retrieved from http://www.titanpipe.com/Engineering_Titan_Industries_In/Water Flow PVC Well Screen.pdf</ref><ref>WaveRail. (n.d.). WATER WELL SCREEN & CASING SYSTEMS. Retrieved March 12, 2018, from http://www.waverail.nl/images/Template_content/PDF/documentatie/Filter-buizen.pdf</ref>. |