Water – smart horticulture at the ANBG

Water targets | Irrigation system | Resources

The Gardens uses around 1.5 megalitres of water per year with most water being used outside.

In recent years, the Australian National Botanic Gardens has made significant water savings.

These savings are in response to our desire to demonstrate sustainable practices and showcase low water use in horticulture, as well as the increased cost of water. The Gardens has met and are exceeding the water saving targets set by our local provider, ACTEW, through the water efficiency measures taken to date, including the installation of a new computerised automatic irrigation system.

Water targets

The continued drought in south-eastern Australia has reduced the supply of available water to homes, businesses and public institutions alike.

The Australian National Botanic Gardens currently uses potable (normal drinking) water supplied by ACTEW for all uses, both indoors and outdoors. Hudsons Café in the Gardens is metered separately.

The Gardens was granted a water exemption from ACTEW to continue watering its irreplaceable living collection. This meant aiming for water savings targets.

The Gardens made changes in its water use to strive to meet these targets by, for example, adjusting watering times and amounts, choosing not to water certain areas in the Gardens and reducing the watering of lawns.

As a longer term solution, the Gardens has a new $2.7m project underway to access and use non-potable water from Lake Burley Griffin for outdoor irrigation.

Irrigation system

The installation in 2005 – 2006 of an $180,000 computerised irrigation system, Irrinet, formed part of the overall water strategy for the Gardens. The new system has helped the ANBG become more efficient in its irrigation water use.

Each horticulturist programs their own water delivery schedule for their sections and receives monthly water usage reports. Knowledge of the plants' water requirements allows them to match the irrigation to the plants' needs.

The analysis of monthly water usage reports highlights any potential problems. Furthermore, the observations of staff and visitors also alert the irrigation officer to any faults in the system. The original steel water pipes used throughout the Gardens are being gradually replaced with PVC plastic pipes.

The automatic irrigation system features a series of drippers, overhead sprinklers, micro-sprayers and ground-level low volume emitters.
The irrigation system consists of:

a dedicated computer running Irrinet software
14 solar-powered, radio controlled water meters on each major line
4 solar-powered, radio controlled water valves
a solar-powered weather station which measures rainfall, temperature, humidity, solar radiation and evaporation.

The Irrinet system is operated from a dedicated PC or by logging in remotely to trouble-shoot or check daily activity. This allows the system to be monitored after hours and the valves can be shut down remotely if required.
Four solar-powered soil moisture sensors are located in different soil types around the Gardens. These sensors are not integrated into the irrigation system, but provide additional information for assessing the soil wetness profile. For instance, the use of the soil sensor in the café lawns can indicate when the lawn is sufficiently well-watered to allow the irrigation system to be turned off.

Resources