Australian Natural Resources Atlas

Natural Resource Topics

Water resources - Management and Development - Queensland

Location map of Mulgrave River

Groundwater Management Unit: Mulgrave River

Introduction

Management Context:

The most significant issue concerning the groundwater resource of the Mulgrave River GMU is the potential impact of providing groundwater to Cairns for their town water supply. Currently groundwater allocations in the GMU amount to over 9000 Ml/yr and with the potential addition of 14000 Ml/yr, for Cairns town supply, the water resource would face over-allocation. At present further simulations and analysis on spacial and temporal variations in water extractions would be necessary to estimate the possibility of obtaining a higher yield.

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

 NO

Subsidence

 NO

Artificial Recharge (ML/yr)

 no data

Ecosystems Protection

 NO

Surface Water Interaction

 NO

Management Plans

 YES

Defined Minimum Water Level

 NO

Comment: No priority issues are reported.

Comments on Management Responses

2020 Management Response:

A forecast use estimate of 15000 Ml/yr in 2020 is based upon current and historical use and includes the supply of town water to Cairns.

2050 Management Response:

A forecast use estimate of 20000 Ml/yr in 2050 is based upon current and historical use and includes the supply of town water to Cairns.

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

Assessment of monitoring in Mulgrave River

Efficacy of the network:

Water level monitoring in the Mulgrave River groundwater management unit commenced in 1976. Levels were taken approximately quarterly with a number of sampling gaps in 1988/89, 1995/96 and a regional sampling gap in 1986. Post 1990 water quality data exists for 47 bores within the GMU. Allocation data is available for the Mulgrave GMU however groundwater abstraction is not metered.

The current monitoring network in the GMU consists of 31 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.

Allocation and use data is obtained through the Water Entitlements Registration Database (WERD) which is an electronic database for water licences.

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. data.

Protective management:

The Russell / Mulgrave Landcare Group operates in the Mulgrave Catchment and address major issues in the area.

Options for monitoring:

A Water Management Plan (WMP) is recommended for implementation in the GMU with the conclusion of the groundwater model for the Mulgrave River alluvial aquifer system.

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 Mulgrave River GMU has an assessed sustainable yield of 20000 Ml/yr. This assessment comes from a groundwater flow model for the Mulgrave River alluvium completed in 1999.

Sustainable yield:

ML/yr

Threshold year for sustainable year:

2,050 

Abstraction Volume 1996/1997:

35 ML 

Current Resource development categorisation:

 

Estimated Use in 2020

Comment:

 

Estimated use in 2020:

15,000 ML 

% change from 1996/1997:

42,758 

Resource development categorisation:

 

Estimated in 2050

Comment:

 

Estimated use in 2050:

20,000 ML 

% change from 1996/1997:

57,043 

Resource development categorisation:

 

What assumptions were used in this assessment

Development Potential:

Although the Mulgrave River GMU falls within the Cairns Coast Declared Sub-Artesian Area only few licences for high yielding bores exist on account of the high annual rainfall. Currently the sustainable yield, of 20000 Ml/yr, will meet the demand. In the event of supplying Cairns with town water however, development potential would be significantly reduced.

Estimate of Use:

Under a high demand scenario, forecast use in the Mulgrave River GMU is estimated to be less than 1200 Ml/yr in 2011. Forecast use in the years 2020 and 2050 however include the supply of town water to Cairns.

Data Availability,Gaps and Recommendations

Data Availablility:

Limited monitoring of groundwater level commenced in 1976 to early 1994 during which time a number of sampling gaps occured in 1986, 1988/89 and 1995/96. Post 1990 water quality data exists for 47 bores within the GMU. Allocation data is available for the GMU however abstraction data is incomplete as there is no groundwater metering.

Current Gaps and Recommendations:

Data Gaps: During the peroid of water level monitoring a number of sampling gaps occurred in 1986, 1988/89 and 1995/96. Abstaction data for the reporting year is also incomplete.

Recommendations: Monitoring of groundwarter levels and qulaity 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:

The Mulgrave River groundwater resource requires continued groundwater quantity and quality monitoring. From groundwater flow modelling of the resource it was also recommended that further simulations and analysis of spatial and temporal variations in water extractions are necessary to estimate the possibility of higher yield

Further information

Key

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