Greening cities in dry times

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Maintaining our urban green spaces (parks, playing fields, golf courses, gardens) provides significant social and economic benefits.

These include, amongst others:

• Positive affects on physical and mental health through the provision of sporting and recreational space (this in turn generates income from festivals and sporting events)
• Positive hydrological impacts through increased water infiltration (less stormwater run-off) and the removal of pollutants such as phosphorus, lead and nitrogen from stormwater
• Producing a cooling effect, thereby potentially reducing building energy consumption

However maintaining these green spaces has become increasingly challenging due to continuing dry conditions, competing house-hold water demands and increasing population. Given current climate change predictions, we will need to continue developing innovative solutions for managing urban green spaces with reduced water availability. To date this has primarily occurred in the areas of:

• Demand management
• Increasing water use efficiency
• Utilisation of alternative water sources

Reducing the demand for water in green spaces can be achieved by:

• Reducing the area that needs to be irrigated – including turning off irrigation and installing hard surface landscapes
• Managing existing landscapes with less water (plants undergo some level of water stress)
• Using more water efficient or drought tolerant species (to realise the potential of these species will also require a good soil profile, checking water quality and ensuring that water can enter the soil and be stored there for plants to use)

Achieving high efficiency in urban irrigation is not straight forward due to shallow rooted vegetation, highly variable soils and multiple plant species of varying water requirements in close proximity. However there is a range of technology and training to aid irrigators in applying water more effectively, such as:

• High uniformity, low precipitation rate sprays for small turf areas
• Subsurface drip for turf and landscapes
• Robust micro-irrigation for landscape areas

While weather stations, soil moisture sensors, and rain sensors and switches etc will assist irrigators to manage soil and weather conditions through efficient scheduling.

Alternative water sources such as recycled water and harvested stormwater are recognised as valuable resources within the integrated water cycle, helping to conserve potable water for high quality needs. Irrigation with recycled water and stormwater may require irrigators to implement additional management practices depending on water quality. These often relate to managing salinity and could include irrigation at night, application of soil amendments, annual soil testing and careful plant selection. Further information on management practices can be found in Irrigation of Amenity Horticulture with Recycled Water (PDF) – A handbook for parks, gardens, lawns, landscapes, playing fields, golf courses and other public open spaces.

Storm-water harvesting is a crucial component of developing water sensitive cities, with removal of pollutants achieved through both vegetated (rain-gardens and wetlands) and non-vegetated methods. Storage of harvested storm-water within urban locations can be problematic, however authorities are increasingly working together to overcome treatment and storage barriers to deliver innovative water sensitive urban design (WSUD) projects.

Further information on WSUD projects can be found at www.watersensitivecities.org.au.

Caption: Werribee Park Golf Course

Citation

Land & Water Australia. 2010. Greening cities in dry times. [Online] (Updated November 29th, 2010)
Available at: http://lwa.gov.au/node/3795 [Accessed Thursday 1st of March 2012 12:30:05 AM ].