Code of Practice - Irrigated Public Open Space - SA Water

5.9 Irrigation management technology
In order to manage irrigation efficiently, daily monitoring
of the weather and soil moisture levels is required. This can
involve ongoing complex calculations and adjustment of
irrigation schedules to respond to the ever changing plant
water requirements. Technologies have been developed to
assist the irrigation manager to monitor climatic and soil
moisture changes and adjust irrigation schedules
automatically as required. Technologies such as
computerised irrigation management systems, weather
stations, soil moisture sensors and rain sensors can all
improve irrigation management.
5.9.1 Weather based irrigation control systems
Irrigation control systems have been developed that use
climatic data to calculate irrigation run times or to schedule
irrigation events. Such systems are a useful tool in managing
irrigation and relieve the irrigation manager from the task of
calculating the irrigation requirement and automatically
adjust irrigation schedules as a function of the weather.
Some systems are fully automatic and are linked to weather
stations from which they retrieve climatic data and
automatically calculate reference ETo and effective rainfall.
The irrigation requirement is then calculated using preset
crop co-efficient and system efficiency factors. Semiautomatic
systems require manual input of a base irrigation
schedule and daily input of reference ETo and effective
rainfall from which the system determines the frequency of
irrigation events.
Services are available whereby irrigation management service
providers access climatic data from a network of weather
stations. The data is processed by a centralised computer and
transmitted to irrigation sites adjusting schedules or
regulating irrigation events according to the weather.
Climatic data can be accessed from either the Bureau of
Meteorology or from private weather stations. A significant
factor in the efficiency of the control system is the quality
of data used.
5.0 TURF & IRRIGATION MANAGEMENT PRINCIPLES
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5.9.2 Weather stations
Weather stations can be installed by organisations to
provide real time climatic data from which reference
evaporation can be calculated. Weather stations are
particularly useful for regional areas where Bureau of
Meteorology data is limited or for specific sites where
climate data is required.
Weather stations used for monitoring reference
evapotranspiration (ETo) should conform to the
requirements specified by the Bureau of Meteorology
and in the FAO Technical Paper No 56.
The following data is required;
• Air temperature.
• Relative humidity.
• Wind speed.
• Solar radiation.
Weather station data is then used by the system to calculate
ETo and subsequent irrigation schedules or events.
5.9.3 Soil moisture based
irrigation control systems
Soil moisture sensors are able to directly record the soil
moisture status of the soil. Information gained from soil
moisture sensors provides both data on soil water reduction
through ETc and a feedback loop which monitors the
accuracy of climate driven irrigation schedules. The sensors
record the net effect of the integration of soil, turf grass,
climate and irrigation to assist with identifying indicators
that drive the decision for irrigation and monitor the
efficiency of irrigation.