Australian Natural Resources Atlas

Natural Resource Topics

Water resources - Management and Development - Queensland

Location map of Braeside / Nebo

Groundwater Management Unit: Braeside / Nebo

Introduction

Management Context:

Declining groundwater levels are a priority issue in the Braeside/Nebo GMU and have elevated community interest in the operation and management of the borefield. Declining groundwater levels, due to prolonged drought conditions, resulted in a suspension in the water supply from the borefield in late 1994. Investigation is currently underway into a proposed expansion of the Braeside borefield with the intention to more evenly distribute pumping rather than to increase overall capacity.

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

 NO

Subsidence

 NO

Artificial Recharge (ML/yr)

 no data

Ecosystems Protection

 NO

Surface Water Interaction

 NO

Management Plans

 NO

Defined Minimum Water Level

 NO

Comment: Declining water levels due to prolonged drought conditions has resulted in suspended water supply

Comments on Management Responses

2020 Management Response:

The estimate of 2500 Ml/yr for the forecast use for the year 2020 is based upon the GMU's assessed sustainable yield, development potential and the desired level of resource management.

2050 Management Response:

The estimate of 2500 Ml/yr for the forecast use for the year 2050 is based upon the GMU's assessed sustainable yield, development potential and the desired level of resource management.

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

Assessment of monitoring in Braeside / Nebo

Efficacy of the network:

The current monitoring network for the Braeside/Nebo groundwater management unit consists of 64 observation bores, with a proposed bi-annual to monthly monitoring frequency.

Continuous monitoring of water levels has occurred since the early 1970's to the present. Management of the Braeside borefield has involved monitoring and maintenance programs to monitor the impact of pumping on groundwater resources. These programs commenced in 1983 and include a detailed review of borefield performance and an impact assessment on the groundwater system every two years.

Water levels are monitored on an approximate quarterly basis by the Department of Natural Resources and on a monthly basis by borefield maintenance personnel. The monitoring of the groundwater level assists in the interpretation of borefield performance and as an indication of aquifer storage. The Braeside/Nebo GMU is overcommitted with respect to groundwater allocation and use, and it is desirable that the proposed level of monitoring continue.

Data management requirements:

Queensland groundwater monitoring data, both water level and water quality, is stored within the Groundwater Database (GWDB) system. The new system is based on web technology and is available through the Department's intranet. Allocation and use data is obtained through the Water Entitlements Registration Database (WERD) which is an electronic database for water licence details. Both databases are managed locally at district level, with respect to the collection and entering of water monitoring, allocation and use data; and are accessed statewide.

Protective management:

Management of the groundwater resource of the Braeside/Nebo groundwater management unit aims at maintaining a longterm, sustainable resource. Protective management requriements for the Braeside/Nebo GMU include:

prevention of intrusion of poor quality groundwater form the flanks of the alluvium where the groundwater is brackish and could migrate if the groundwater sytem is placed under stress;

a revision of groundwater allocation, through a survey of actual groundwater usage compared to allocation, which may allow for increased potential for development by 'freeing up' unused allocations.

Options for monitoring:

Options for Commonwealth and State agencies to address data and information gaps include:

a revision of groundwater allocation, through a survey of actual groundwater usage compared to allocation., which may allow for increased potential for development by 'freeing up' unused allocations.

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: 

An assessment of 2500 Ml/yr for sustainable yield was made in 1999, based upon a finite difference groundwater flow model and water balance calculations. The sustainable yield is inadequate to meet the borefield's existing allocation requirements of approximately 3250 Ml/annum.

Sustainable yield:

ML/yr

Threshold year for sustainable year:

1,997 

Abstraction Volume 1996/1997:

2,800 ML 

Current Resource development categorisation:

Estimated Use in 2020

Comment:

Estimated use in 2020:

2,500 ML 

% change from 1996/1997:

-10 

Resource development categorisation:

Estimated in 2050

Comment:

Estimated use in 2050:

2,500 ML 

% change from 1996/1997:

-10 

Resource development categorisation:

 

What assumptions were used in this assessment

Development Potential:

The Braeside borefield was initially considered to be a temporary water supply that would allow development of the mining ventures to proceed whilst the proposed Spencer Dam on Denison Creek was to be constructed jointly by mining companies. However, due to a downturn in the coal mining industry in the 1970's, and the time and cost involved in building and commissioning a major storage, the construction of Spencer Dam was abandoned. A 1983 report indicated that sufficient supplies would be available for operation of the borefield for a maximum of approximately 5 years, after which time supplies available to the borefield would become severely depleted. However, the Braeside borefield remains operational to date and has produced an average abstraction of approximately 2800 ML/annum since the commissioning of the borefield in 1983.

Increasing pressure is being placed upon water resources within the GMU due to increasing competition from potential users within catchments upstream of the borefield, and the potential impact these activities will have on recharge to the borefield. The development potential of the groundwater resources within the GMU are considered to be low. A revision of groundwater allocation, through a survey of actual groundwater usage compared to allocation.,may allow for increased potential for development by 'freeing up' unused allocations.

Estimate of Use:

The estimate of 2500 Ml/yr for the forecast use for the years 2020 and 2050 is based upon the GMU's assessed sustainable yield, development potential and the desired level of resource management.

Data Availability,Gaps and Recommendations

Data Availablility:

In excess of 200 observation bores, both private and State owned, are located within the Braeside/Nebo GMU. The availability of water level data is high, with continuous water level monitoring in 64 observation bores from 1975 to the present. Comprehensive water quality data exists for 20 observation bores within the GMU with recent analyses from 1992 to the present. Use and allocation data is available, as the GMU is within the declared Braeside sub-artesian area.

Current Gaps and Recommendations:

Data Gaps: Indescriminate water level data gaps, of up to four years, exist in the hydrographs for most bores in the Braeside GMU. No metered groundwater abstraction data for irrigation bores is available.

Recommendations: A revision of groundwater allocation, through a survey of actual groundwater usage compared to allocation.,may allow for increased potential for development by 'freeing up' unused allocations.

Future Gaps:

A revision of groundwater allocation, through a survey of actual groundwater usage compared to allocation.,may allow for increased potential for development by 'freeing up' unused allocations.

Further information

Key

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