Australian Natural Resources Atlas

Natural Resource Topics

Water resources - Management and Development - Queensland

Location map of Burdekin River Delta

Groundwater Management Unit: Burdekin River Delta

Introduction

Management Context:

Saltwater intrusion of the groundwater resouces of the Burdekin River Delta groundwater management unit was highlighted as a problem in 1935 following an extended drought, during 1930 - 1935, which resulted in extreme reductions in groundwater levels below sea level due to excessive use. Excessive demand placed upon the groundwater resources within the GMU has resulted in water level declines and degradation of water quality in some areas of the GMU. The water overdraft situation was finally addressed during the severe drought of 1965 with the implementation of an artificial groundwater recharge scheme. Management of the water resources within the GMU have significantly changed since the implementation of the artificial recharge scheme, with the system now considered one of conjunctive use of both surface and groundwater supplies.

Maintenance of the artificial recharge scheme to encourage replenishment and development of recharge pits is critical to ensuring the long term sustainability of irrigation based farming operations in the GMU. The current development of a groundwater management model for the GMU area aims to assist in evaluating the long-term water management strategies.

Elevated iron concentration presents as another water quality priority issue within the Burdekin River Delta GMU. Elevated iron levels in groundwater reduces irrigation efficiency through soil degradation, and reduces pumping efficiency following iron precipitation in bores.

Other water quality issues within the GMU occur along the western margin of the GMU where the Burdekin River Delta GMU meets the Giru Benefitted Area GMU, as groundwater of a reduced quality flows from the Giru Benefitted Area GMU into the Burdekin River Delta GMU.

Priority issues

Declining Water Levels

 NO

Salt Water Intrusion

 YES

SALINISATION

Dryland

 NO

Irrigation

 YES

Groundwater

 YES

Surface Water

 NO

Urban

 NO

Point Source Pollution

 YES

Diffuse Source Pollution

 YES

Subsidence

 NO

Artificial Recharge (ML/yr)

 80,000

Ecosystems Protection

 YES

Surface Water Interaction

 NO

Management Plans

 NO

Defined Minimum Water Level

 NO

Comment: The aquifer of the Burdekin Rive Delta GMU is susceptible to both point and diffuse source pollution from leaking septic tanks, and fertilizer and pesticide application respectively, due to the unconfined nature of the aquifer.

Comments on Management Responses

2020 Management Response:

The estimate of 350000 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 350000 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 Burdekin River Delta

Efficacy of the network:

The current monitoring network for the Burdekin River Delta groundwater management unit consists of 268 observation bores, with a proposed bi-annual to monthly monitoring frequency and includes two automatic data loggers.

A number of observation bores within the Burdekin River Delta GMU have been specifically constructed to locate the fresh/salt water interface and monitor the movement of the saltwater wedge. These particular observation bores have continuously slotted casing which enables monitoring to consist of conductivity readings recorded at 1 m intervals from the water level to the base of the bore. The existing groundwater monitoring network within the GMU is adequate for the detection of further seawater intrusion or a marked rise in the water table, and observation bores should continue to be measured for water level, major ions, pH, and conductivity and salinity movements.

Monitoring of water levels and complete water quality (including nutrients) is essential to the management facilitating integration between surface water and groundwater resources, and enabling swift management response to changes in water quality.

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 license 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 Burdekin River Delta GMU aims at maintaining a longterm sustainable resource. Coastal aquifers prone to salt water intrusion, such as those of the Burdekin River Delta GMU, remain capable of yielding a sustainable source of freshwater if protective and flexible management practices are implemented. Protective management requirements for the Burdekin River Delta GMU include:

maintenance of the artificial recharge scheme, with respect to replenishment encouragement and the development of recharge pits, to ensure the long term sustainability of irrigation based farming operations in the GMU;

development of a groundwater management model for the GMU area to assist in evaluating the long-term water management strategies (currently underway);

consideration of the long term protection of the groundwater system from saltwater intrusion, with maintenance and continuation of water level and water quality monitoring;

maintenance of the Burdekin River, with respect to environmental needs and environmental flow requirements.

Options for monitoring:

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

addressing monitoring frequency requirements with respect to saltwater intrusion and the movement of salinity from Mt Kelly and Stokes Range,

addressing the effects of elevated iron concentration in groundwater and the effect upon irrigation efficiency and pumping efficiency,

maintenance of the artificial recharge scheme and assessment of recharge efficiency with respect to quantifying recharge.

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 350000 Ml/yr for sustainable yield of the Gurdekin River Delta groundwater management unit was made in 2000 based upon a preliminary water balance study, with approximately 80000 Ml/yr of the sustainable yield attributed to artificial recharge, 20000 Ml/yr to the Burdekin River, and 250000 Ml/yr to floods and rainfall.

Sustainable yield:

ML/yr

Threshold year for sustainable year:

1,970 

Abstraction Volume 1996/1997:

350,000 ML 

Current Resource development categorisation:

Estimated Use in 2020

Comment:

Estimated use in 2020:

350,000 ML 

% change from 1996/1997:

0 

Resource development categorisation:

Estimated in 2050

Comment:

Estimated use in 2050:

350,000 ML 

% change from 1996/1997:

0 

Resource development categorisation:

 

What assumptions were used in this assessment

Development Potential:

The groundwater resources of the Burdekin River Delta groundwater management unit are not expected to sustain any significant increase in development, due to variable quality and quantity. Although the artificial groundwater recharge scheme has resulted in reducing the over use of groundwater, the groundwater system remains threatened by saltwater intrusion.

Development of a groundwater management model to enable the evaluation of water management strategies, ensuring sustainable irrigation, is presently underway. Maintenance of the artificial recharge scheme to encourage replenishment and development of recharge pits is critical in ensuring the long term sustainability of irrigation based farming operations in the GMU. The current development of a groundwater management model for the GMU area aims to assist in evaluating the long-term water management strategies.

Estimate of Use:

The estimate of 350000 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 1700 observation bores, both private and state owned, are located within the Burdekin River Delta GMU. The availability of water level data is high, with water level monitoring conducted in 168 observation bores, some from 1951 to the present, on an approximately bi-monthly basis. Comprehensive water quality data exists for 293 observation bores within the GMU, with recent analyses to 1998.

Current Gaps and Recommendations:

Data Gaps: A survey of private groundwater facilities and water demand in the GMU is presently underway and aims to address data gaps pertaining to the demand for water generated by different land uses and the extent and behaviour of the groundwater system, culminating in the development of a groundwater management model. Additional data is required to determine the hydraulic characteristics and extent of the aquifer, and soil infiltration rates.

Recommendations: Pump test analysis is required to determine the hydraulic characteristics of the aquifer, with additional sub-surface investigation required to assist in defining the extent of the aquifer and identifying better aquifer materials. A detailed soil survey is required to determine infiltration rates.

Future Gaps:

Information needs and gaps for the Burdekin River Delta groundwater management unit include:

pump test analysis to determine the hydraulic characteristics of the aquifer, with additional sub- surface investigation to assist in defining the extent of the aquifer and identifying better aquifer materials, with infiltration rates determined through a detailed soil survey;

evaluation of the change in use of water resources within the GMU, from groundwater to the conjunctive use of surface and groundwater resources, following the introduction of the artificial groundwater recharge scheme;

consideration of the long term protection of the groundwater system from saltwater intrusion;

development of a management plan which will consider the potential for future expansion of groundwater use within the GMU.

Further information

Key

   Links to an another web site
   Opens a pop-up window