Local climatic and environmental considerations

Chapter 5 of the Natural Grass vs. Synthetic Turf Surfaces Study Final Report.

An additional key component of the decision making process is the local climatic and environmental factors which affect the local region.  In particular the water supply, rainfall events and other weather conditions.  Western Australia has been experiencing a period of drought conditions and in some areas access to a reliable water supply for irrigating sports grounds has been limited.  These considerations are elaborated on below. 

Water supply

There are two principle water supplies available for irrigating natural grass sports facilities in Perth. Water Corporation is responsible for “Scheme” water and The Department of Water is responsible for bore water.  Reclaimed water, storm water and other alternatives are available for irrigation in varying capacity across the state. Local waste water treatment schemes may be available in regional areas.  In some regional areas it is understood that potable water is currently being transported in to maintain sports grounds due to a shortage of water from usual sources.

The majority of natural grass sports surfaces are watered using ground water bores managed by the Department of Water. Licences are issued to users, generally through Local Government.  The licence conditions state the quota and conditions of usage. Generally bore water used for irrigating sports fields is allowed on 3 days per week between the hours of 6.00 pm and 9.00 am with further irrigation subject to exemption permit. There is no charge for bore water other than an annual licence fee and pumping costs (as at December 2011). Ground water areas are at their sustainable limit and it is understood that it is unlikely that bore licences will be granted for new users or increased for existing users.

Water Corporation ‘scheme water’ is available for use for irrigating sports grounds subject to water wise measures similar to the use of bore water. Irrigation is permitted on 3 days per week between the hours of 6.00 pm and 9.00 am with further irrigation subject to exemption permit. The cost of scheme water for 2011/12 is $1.72 kL with additional charges depending on the size of the water supply metre.

Further and current information on water supply costs, watering times options is available from Water Corporation and Department of Water

Irrigation requirement

The irrigation requirement for both warm and cool season’s natural grass, for varying quality of natural sports turf, has been calculated using the models developed as part of the ‘Code of Practice – Irrigated Public Open Space’[1].

The ‘Turf Quality Visual Standard’ (TQVS) classification system was developed in the Code of Practice. The TQVS system has 4 classifications of natural turf and is shown in the table below.

Table 1: Turf Quality Visual Standard Classification System

TQVS Classification

Description

Comment

1

Elite Sports Turf

International/National Level Sport: e.g. WACA, Subiaco Oval, Perth Oval

2

Premier Sports Turf

State/Regional/District Level Sport: e.g. Leederville Oval, Baseball Park, Fremantle Oval

3

Local Sports Turf

Local Level Sports: e.g. local based sports grounds’

4

Passive Recreational Turf

Non-Sports Turf: e.g. Community parks/Passive reserves

The irrigation requirement for elite sports turf is higher than that for premier or local sports turf. Likewise the irrigation requirement for cool season grasses is higher than that for warm season grasses.

High irrigation requirement occurs in conditions where there is least rainfall and high evapotranspiration (Etc). For Perth this is in the warmer months from September to March as illustrated in Figure 1 below.

Relationship between rainfall and turf water management table

Figure 1: Relationship between Rainfall and Turf Water Requirement

Using climatic data for the Bureau of Meteorology weather station located at Perth Airport, the irrigation requirement for the 4 TQVS classifications of natural grass using cool and warm season natural grass has been calculated and can be seen in Table 2 below.

Table 2: Irrigation Requirements for the 4 TQVS Classification of Natural Grass

TQVS

Classification

Description

Irrigation Requirement

Cool Season Turf

kL / ha

Irrigation requirement

Warm season Turf

kL / ha

1

Elite Sports Turf

15,840

11,830

2

Premier Sports Turf

9,040

6,780

3

Local Sports Turf

7,520

5,520

4

Passive Recreational Turf

5,990

4,260

 

Warm season natural grass uses between 35 – 40% less water than cool season natural grass and irrigation requirements for local natural sports turf is approximately 50% less than elite natural sports turf.