Section 7 Irrigation System Auditing
Questions with Correct Answers
10.1 What is the purpose of an irrigation system audit - ANSWERSThe purpose of an
irrigation system audit is to asses how effective an irrigation system is at applying water
to a specific hydrozone.
10.2 True or false: A high DU is desirable because it allows the entire root zone to be
irrigated more evenly. - ANSWERSTrue. Distribution uniformity is a measurement of
how evenly water is applied to a hydrozone. A high DU is desirable because it allows
the entire root zone to be irrigated sufficiently and evenly.
10.3 True or false: DU and IE are the same? - ANSWERSFalse. DU is a measurement
of how evenly water is applied to a hydrozone. IE is the ratio of the volume of water that
is beneficially used by the plants in a hydrozone to the volume of irrigation water
applied.
10.4 Why is head-to-head coverage of overhead spray desirable - ANSWERSHead-to-
head coverage of sprinkler spray patterns is typically used to ensure optimal DU.
Coverage between the two will be uniform. *Think of VenDiagram where A UNION B
10.5 What are some causes of poor DU and IE? - ANSWERS1. Improper head spacing
(less than head-to-head spacing)
2. Use of different head types in the same zone, e.g. rotors with spray sprinklers.
3. Water pressure that is too high, causing misting, or too low, reducing the radius of
throw.
10.6 What is the difference between the gross and net precipitation rate? -
ANSWERSGross precipitation rate measures the total flow of the hydrozone.
Net precipitation rate applied measures only the water that is effectively applied to the
hydrozone landscape area.
10.7 True or false: When the PR is matched, the flow rate of the emission device
increases as the arc increases? - ANSWERSTrue. This applies to individual emission
devices to ensure an even rate of water application.
10.8 True or false: When the PR is unmatched, the flow rate of the emission device
remains constant as the arc increases? - ANSWERSTrue. The precipitation rate of a
180-degree head is half that of a 90-degree head.
10.9 True or false: Manufacturers specifications can be used to look up the net PR? -
ANSWERSFalse.
Questions with Correct Answers
10.1 What is the purpose of an irrigation system audit - ANSWERSThe purpose of an
irrigation system audit is to asses how effective an irrigation system is at applying water
to a specific hydrozone.
10.2 True or false: A high DU is desirable because it allows the entire root zone to be
irrigated more evenly. - ANSWERSTrue. Distribution uniformity is a measurement of
how evenly water is applied to a hydrozone. A high DU is desirable because it allows
the entire root zone to be irrigated sufficiently and evenly.
10.3 True or false: DU and IE are the same? - ANSWERSFalse. DU is a measurement
of how evenly water is applied to a hydrozone. IE is the ratio of the volume of water that
is beneficially used by the plants in a hydrozone to the volume of irrigation water
applied.
10.4 Why is head-to-head coverage of overhead spray desirable - ANSWERSHead-to-
head coverage of sprinkler spray patterns is typically used to ensure optimal DU.
Coverage between the two will be uniform. *Think of VenDiagram where A UNION B
10.5 What are some causes of poor DU and IE? - ANSWERS1. Improper head spacing
(less than head-to-head spacing)
2. Use of different head types in the same zone, e.g. rotors with spray sprinklers.
3. Water pressure that is too high, causing misting, or too low, reducing the radius of
throw.
10.6 What is the difference between the gross and net precipitation rate? -
ANSWERSGross precipitation rate measures the total flow of the hydrozone.
Net precipitation rate applied measures only the water that is effectively applied to the
hydrozone landscape area.
10.7 True or false: When the PR is matched, the flow rate of the emission device
increases as the arc increases? - ANSWERSTrue. This applies to individual emission
devices to ensure an even rate of water application.
10.8 True or false: When the PR is unmatched, the flow rate of the emission device
remains constant as the arc increases? - ANSWERSTrue. The precipitation rate of a
180-degree head is half that of a 90-degree head.
10.9 True or false: Manufacturers specifications can be used to look up the net PR? -
ANSWERSFalse.
