Reports > CHO Concepts and Design


ITRC Report No. R 22-001.  Charles Burt

CHO Concepts and Design for Turnout Flow Measurement

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A CHO (constant head orifice) is a common outlet for flows ranging from 1 to 30 CFS. The CHO is popular in some western USA irrigation districts. With minimal training, operators can control and measure flow rates within five percent of the tabular values they have. Unfortunately, some of the details provided in USBR design manuals are incomplete, so the flow tables are inaccurate. This and other problems can be avoided by following the procedures laid out in this report.


Burt, C. 2022. CHO Concepts and Design for Turnout Flow Measurement. Irrigation Training & Research Center, California Polytechnic State University, San Luis Obispo, California, USA. ITRC Report No. R 22-001. 17 pp.

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