Australian Natural Resources Atlas

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Water resources - Management and Development - Queensland

Location map of Tully / Murray Rivers

Groundwater Management Unit: Tully / Murray Rivers

Introduction

Management Context:

Assessment of the Tully and Murray Rivers GMU has identified three groundwater-related issues concerned with:

- Preservation of groundwater supplies for domestic and irrigation purposes in the unconfined alluvium;

- The effects of drainage on groundwater quantity and quality; and

- Preservation of the unconfined alluvium from contamination.

Due to very high rainfall in the GMU there is a need to drain surface water and near surface groundwater at the conclusion of wet seasons (April to May). Drainage networks allow for viable crop management following wet periods however their implementation can effect groundwater quantity and quality.

Recharge to the unconfined alluvial aquifer, which occurs mainly by direct infiltration of rain, is enhanced by the presence of a head of water. The presence of a drainage system therefore affects infiltration by reducing head. Furthermore it is anticipated that a smaller net recharge would result in such a situation. Introduction of a close drainage network would also significantly impact on the ability of the aquifer to maintain reliable supplies later in the year (October December).

The unconfined aquifer is also highly susceptible to contamination. The sandy nature of the aquifer and rapid response to rainfall, means that contaminants would be quickly delivered to the aquifer. The contaminants that may commonly put the aquifer at risk include septic effluent, agricultural fertilisers, oil and petroleum products, pesticides and herbicides.

Priority issues

Declining Water Levels

 NO

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

 YES

Defined Minimum Water Level

 NO

Comment: The flooding nature of the area within the GMU necessitates a drainage network for viable crop management. This would however have groundwater quality and quantity concerns.The sandy nature of the aquifer make it highly susceptible to contamination.

Comments on Management Responses

2020 Management Response:

Forecast use is estimated to reach a maximum level of 3000 Ml/yr in the year 2020 bases upon historical estimates of use and development potential of the Tully and Murray Rivers GMU.

2050 Management Response:

Forecast use is estimated to reach a maximum level of 6000 Ml/yr in the year 2050 bases upon historical estimates of use and development potential of the Tully and Murray Rivers GMU.

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

Assessment of monitoring in Tully / Murray Rivers

Efficacy of the network:

Monitoring of bore water levels in the Tully and Murray Rivers GMU commenced in 1987, for a limited number of bores, and between 1992 to 1994 for the majority of the bores. Levels were taken approximately quarterly with a common sampling gap in 1991/92. Post 1990 water quality data exists for 71 bores and there is no abstraction data as there is no metering in the GMU.

The current monitoring network for the Tully and Murray Rivers groundwater management unit consists of 43 observation bores with a proposed bi-annual to monthly monitoring 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. The databases is managed at a district level, with respect to the collection and entering of water monitoring data; and is accessed statewide.

Protective management:

Management of the groundwater resource of the Tully and Murray Rivers groundwater management unit aims at maintaining a longterm, sustainable resource and therefore, requires continued monitoring of water level and water quality.

Options for monitoring:

The aquifers in the Tully and Murray Rivers GMU are identified as being commonly at risk from contamination from septic effluent, agricultural fertilisers, oil and petroleum products, pesticides and herbicides. It is recommended that a community education program is implemented to provide a set of management practices for the use of chemicals, fuel and septic systems in the GMU.

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: 

The sustainable yield, from the alluvial aquifers within the GMU, is estimated to be around 19000 Ml/yr with a further 1500 Ml/yr available from overlying sand dune deposits.

Sustainable yield:

ML/yr

Threshold year for sustainable year:

2,100 

Abstraction Volume 1996/1997:

2,000 ML 

Current Resource development categorisation:

 

Estimated Use in 2020

Comment:

 

Estimated use in 2020:

3,000 ML 

% change from 1996/1997:

50 

Resource development categorisation:

 

Estimated in 2050

Comment:

 

Estimated use in 2050:

6,000 ML 

% change from 1996/1997:

200 

Resource development categorisation:

 

What assumptions were used in this assessment

Development Potential:

Groundwater in the Tully and Murray Rivers GMU is utilised extensively for domestic supplies and the irrigation of bananas while sugar cane and watermellon crops are minor users. As the area is not declared, or subject to groundwater use regulations, no licence is required by land owners to drill for or use groundwater. There may therefore be unidentified irrigation bores in the GMU and with expansion in the banana industry increases in groundwater use are anticipated. Based on sustainable yield and use estimates there is about 17000 Ml/yr available for development on the assumption that there is full recharge in the wet season.

Estimate of Use:

Forecast use estimates in Tully and Murray Rivers GMU for the years 2020 and 2050 are based upon historical estimates of use and development potential.

Data Availability,Gaps and Recommendations

Data Availablility:

Limited monitoring of groundwater level commenced in 1987 and is proposed to continue in the current monitoring network of 43 observation bores. Gaps in sampling, in most bores, occur in 1991/92. Post 1990 water quality data exists for 71 bores within the GMU and there is no metering of groundwater use.

Current Gaps and Recommendations:

Data Gaps: Sampling gaps in most bores, occur in 1991/92 in the Tully and Murray Rivers GMU and there is no metering of groundwater use.

Recommendations: Monitoring of groundwarter levels and quality should continue in the observation network on a bi-annual to monthly frequency. There is however no current need to meter groundwater abstractions.

Future Gaps:

With the exception of continued monitoring of water level and water quality in the Tully and Murray Rivers GMU, no information needs or gaps are identified.

Further information

Key

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