Australian Natural Resources Atlas

Natural Resource Topics

Water resources - Management and Development - Queensland

Location map of Rochedale

Groundwater Management Unit: Rochedale

Introduction

Management Context:

Issues of high priority in the Rochedale GMU pertain to the degradation of groundwater quality and quantity. Increasing numbers of bores in the GMU have caused depletion of groundwater supplies and a resultant fall in bore water level, while changes in farming practices and crop type have lead to a reduction in water quality. These issues are likely to continue if proper management of the aquifer is not initiated and current levels of activity (in late 1990s) continue. However a move to urban land use practices may see a reduction in stress on the system.

Strategies suggested to better manage irrigation practices in response to falling water levels include: (1)Regulated use of groundwater by licencing and monitoring abstraction, (2) changing irrigation practices, (3) controlled drainage to increase percolation to the vadose zone.

Recommendations to control chemical pollution include: (1)Using fertilisers that do not leach readily into the underlying groundwater, (2)not fertilizing when heavy rain is expected but trying to control fertilizer to stay in the root zone for as long as possible and (3) reducing the amount of fertilizer being used by planting more resistant crop varieties and/or using more effective spraying techniques.

Priority issues

Declining Water Levels

 YES

Salt Water Intrusion

 NO

SALINISATION

 

Dryland

 NO

Irrigation

 NO

Groundwater

 NO

Surface Water

 NO

Urban

 NO

Point Source Pollution

 NO

Diffuse Source Pollution

 YES

Subsidence

 NO

Artificial Recharge (ML/yr)

 no data

Ecosystems Protection

 NO

Surface Water Interaction

 NO

Management Plans

 NO

Defined Minimum Water Level

 NO

Comments on Management Responses

2020 Management Response:

A forecast use estimate of 300 Ml/yr is made for the Rochedale GMU in 2020. This forecast assumes that less than one quarter of the sustainable gorundwater yield will be utilised in 2020 due to urbanisation and the subsequent changed in land use.

2050 Management Response:

A forecast use estimate of 50 Ml/yr is made for the Rochedale GMU in 2050. This forecast assumes that groundwater use will be limited to domestic urban gardens due to urbanisation and the susequent changes in land use.

See QLD Water Resources Assessment 2000 Technical Report for a review of management responses.

Assessment of monitoring in Rochedale

Efficacy of the network:

Monitoring of water levels in two bores commenced in 1987 and continues on a monthly to three monthly frequency. Water quality data is limited, for 3 bores within the GMU,from 1987 to 1990. There are no groundwater use figures available.

No monitoring bores were proposed for the Rochedale GMU in the 1997 review into the Queensland Groundwater Monitoring Network. The two bores currently monitored by QUT will however continue to be monitored at a monthly to quarterly frequency.

Data management requirements:

Queensland groundwater monitoring data, including water level and water quality, is stored within the Groundwater Database (GWDB) system. The new GWDB system uses web technology and is available through the Department's intranet.

Data is currently collected by QUT in two ex-department monitoring bores in the Rochedale GMU. This data is supplied to the Department and will continue to supplement the Rochedale data set in the GWDB.

Protective management:

The Rochedale GMU is a non-active Department of Natural Resources area however still records water level fluctuations through the Queensland University of Technology. This monitoring is proposed to continue into the future. A groundwater quality survey should also be conducted to ensure the resource is not degraded from over use of fertilisers.

Options for monitoring:

Water level monitoring by Queensland University of Technology should continue at current levels in the Rochedale GMU. A groundwater quality study should be completed as soon as possible with government chemical laboratory analysis of samples from a suit currently used bores. Testing for known commonly used chemical species including trace metals, pesticides, herbicides and others would be valuable in assessing the condition of the resource.

See QLD Water Resources Assessment 2000 Technical Report for a review of monitoring.

What is the estimated demand for groundwater?

Sustainable Yield

Comment about sustainable yield figure: 

A sustainable yield of 1300 Ml/yr is estimated for the Rochedale GMU at supply rates up to 8.80 l/s in the deepest part of the lower aquifer. The sustainable yield was calculated on the assumption that a safe supply would be equivalent to the long term average annual recharge. The recharge was however assessed on a limited period of water level monitoring in the area and does not meet the existing use.

Sustainable yield:

ML/yr

Threshold year for sustainable year:

1,990 

Abstraction Volume 1996/1997:

2,000 ML 

Current Resource development categorisation:

 

Estimated Use in 2020

Comment:

 

Estimated use in 2020:

300 ML 

% change from 1996/1997:

-85 

Resource development categorisation:

 

Estimated in 2050

Comment:

 

Estimated use in 2050:

50 ML 

% change from 1996/1997:

-97 

Resource development categorisation:

 

What assumptions were used in this assessment

Development Potential:

Groundwater in the Rochedale GMU aquifers is under stress from overuse and concentration of agricultural chemical products. Poor water quality and/or low supplies severely limits the groundwater development potential of the aquifers within the groundwater management area.

Comparison of abstraction estimates and sustainable yield for the aquifers indicates that groundwater is fully developed, and over- abstracted. Present groundwater use of approximately 2000 Ml/yr is well over the estimated optimal extraction of 1300 Ml/yr. Aquifers therefore have no potential for development. An additional hindrance to the development of the Sunnybank Formation aquifer is its high susceptibility to contamination by leaching of pollutants.

Estimate of Use:

With the anticipation of urbanisation it is likely that gorundwater use will reduce accordingly. Estimates of forecast groundwater use in 2020 and 2050 are based on urbanisation and the subsequent changes in land use.

Data Availability,Gaps and Recommendations

Data Availablility:

There is very little recorded data for the Rochedale GMU. Water level monitoring commenced in 1987 to late 1989 and then from 1993 onwards in only two observation bores. Limited water quality data exists for 3 bores within the GMU with most recent analysis from 1987 to 1990.

Additional data is derived from a 1993 thesis and journal paper, covering hydrogeology and chemistry of the Rochedale Basin.

Current Gaps and Recommendations:

Data Gaps: Water level and quality monitoring data is very limited for the GMU. Between 1987 and 1993 water level sampling gaps occurred from 1990 to 1992 while water quality data is available for only 3 bores over the period from 1987 to 1990. No abstraction data is available for the GMU.

Recommendations: It is recommended that monitoring in of the two observation bores in the GMU continue without need to expand the network. Due to the potential for groundwater to become polluted from excessive fertiliser use, water quality/chemistry should also be checked intermittently and include investigation of private bores.

Future Gaps:

Although there is limited interest in the Rochedale GMU from the Deparment of Natural Resources, a groundwater quality survey should be conducted to ensure the resource is not degraded from fertiliser use. Water level monitoring should also continue at the current frequency.

Further information

Key

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