NZQA Expiring unit standard
20956 version 2
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Title
Determine hydraulic parameters for an irrigation system
Level
4
Credits
8
Purpose
People credited with this unit standard are able to confirm
water delivery specifications for an irrigation system, and
perform hydraulic calculations for a pressurised irrigation
system.
Classification
Water Industry > Irrigation
Available grade
Achieved
Explanatory notes
1
Legislation relevant to this unit standard includes but is not limited to the Health and
Safety in Employment Act 1992.
2
Definition
Organisational procedures – the verbal and written instructions to staff on irrigation
system performance.
Outcomes and evidence requirements
Outcome 1
This unit standard is
Evidence requirements
expiring
Confirm water delivery specifications for an irrigation system.
1.1
Soil characteristics are identified, and hydraulic properties determined, for a
specified irrigation system.
Range
1.2
texture, rooting depth, available water holding capacity (AWC),
infiltration, drainage, structure, current land use.
Potential environmental impacts of irrigation activities, and environmental
factors that may affect irrigation activities, are described for a specified irrigation
system.
Range
impacts – stream flow, groundwater resources, recharge, leaching,
biodiversity;
factors – flow/water level restrictions, allocation limits.
Primary Industry Training Organisation
SSB Code 101558
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
1.3
Plant and/or crop water requirements are calculated for identified growth and
climate variables.
Range
1.4
20956 version 2
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crop growth stage descriptors (emergence, growth, maturity,
harvest, post-harvest), leaf area indexes, solar radiation
input/interception, influence of advective winds.
Water requirements are determined for specified areas and crops to be
irrigated.
Range
maximum, 7-day peak, seasonal, annual, return interval average.
Outcome 2
Perform hydraulic calculations for a pressurised irrigation system.
Evidence requirements
2.1
Static pressures between water source and delivery points are determined.
2.2
Pressure losses resulting from elevation differences, and flow in pipes of
various diameters and materials, are calculated for a given system at a range of
flow rates.
Range
2.3
Pressure losses resulting from system components are evaluated, and
components are selected for compatibility with pipes, and to achieve minimal
friction losses.
2.5
Hydraulic parameters are calculated for a given system.
Range
2.6
components include but are not limited to – fittings (tees, elbows,
nipples), valves (gate, float, ball, foot, non-return, pressure
limiting), filters, injectors, meters, drive units.
This unit standard is
Total friction loss is calculated
for a given system.
expiring
Range
2.4
includes but is not limited to – PVC, polyethylene, galvanized,
uniform and uniformly decreasing flow.
may include but is not limited to – dynamic pressure, sprinkler or
emitter operating pressure and acceptable pressure range, total
system flow, pressure requirements at off-takes, allowable
pressure loss in distribution and headworks, total required
dynamic pump pressure, velocity.
Flow through orifices of different designs and sizes is calculated for a range of
pressures and an emitter pressure:flow relationship is determined.
Range
at least two pressures; designs may include but are not limited to –
simple orifice, long path, pressure compensation emitters.
Primary Industry Training Organisation
SSB Code 101558
 New Zealand Qualifications Authority 2016
NZQA Expiring unit standard
20956 version 2
Page 3 of 3
Replacement information
This unit standard and unit standards 25139, 25140,
25141, 25135, have been replaced by unit standard
28932
This unit standard is expiring. Assessment against the standard must take place by
the last date for assessment set out below.
Status information and last date for assessment for superseded versions
Process
Version Date
Last Date for Assessment
Registration
1
19 August 2004
31 December 2020
Review
2
20 August 2015
31 December 2020
Consent and Moderation Requirements (CMR) reference
0179
This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Please note
Providers must be granted consent to assess against standards (accredited) by NZQA,
before they can report credits from assessment against unit standards or deliver courses
of study leading to that assessment.
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and
which are assessing against unit standards must engage with the moderation system that
applies to those standards.
This unit standard is
expiring
Requirements for consent to assess and an outline of the moderation system that applies
to this standard are outlined in the Consent and Moderation Requirements (CMR). The
CMR also includes useful information about special requirements for organisations wishing
to develop education and training programmes, such as minimum qualifications for tutors
and assessors, and special resource requirements.
Primary Industry Training Organisation
SSB Code 101558
 New Zealand Qualifications Authority 2016