Australian Natural Resources Atlas

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Water resources - Availability - Northern Territory

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Northern Territory

Northern Territory Overview

With a comparatively small population base and low intensity of land use, there has been relatively little pressure on the Northern Territory's (NT) water resources to date. This, however, is changing, and increasingly the NT's largely intact water resources are becoming subject, generally locally, to a complex range of needs and demands.

As demand on the NT's water resources grows, along with increased awareness in the community of environmental issues, so to do the demands on assessment, planning and sustainable development of the water resources. The NT has an extreme range of climatic zones, limited data across most areas and a resource knowledge base limited to areas of current demand. Much assessment work is still required to better understand issues like environmental flow requirements and surface water - groundwater interaction in order to enable effective management of the water resources.

Surface Water Reporting Units

Forty Surface Water Management Areas (SWMAs) have been defined, and 38 of them are same as the respective basins designated by the Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) within NT, and are shown in Figure 1. This includes nine management areas (001.NT, 005.NT, 007.NT, 023.NT, 026.NT, 809.NT, 810.NT, 910.NT and 912.NT) which represents the NT portion of the respective basins. The Finniss River basin has been further subdivided to distinguish between developed and undeveloped river systems.

Groundwater Reporting Units

Groundwater information has been reported at two levels - Groundwater Management Units (GMUs) and Unincorporated Areas (UAs). Eight GMUs have been reported and these are selected major aquifer systems within gazetted Water Control Districts. The UAs comprise the majority of the NT and these are classified according to Groundwater Sub-Province (major aquifer) and typical bore yield. Some 46 Unincorporated Areas have been defined. Both GMUs and UAs are sub-areas of Groundwater Provinces which are the hydrogeological basins within the NT and the unit of reporting for the 85 Review.

For further information, contact the Northern Territory Department of Natural Resources, Environment and The Arts www.nreta.nt.gov.au.

How much surface water does Northern Territory have?

Hydrology

The mean annual flow (MAF) of all NT SWMAs is 75,400 GL. The NT can be considered to have two climatic zones, humid and arid. The boundary of these two zones approximates the catchment boundary of the streams that flow to the north (to the Timor Sea and Gulf of Carpentaria) and the streams that flow to the south (to inland ephemeral lakes and floodouts).

River flows in the humid zone have a distinct seasonal pattern and moderately low year to year variability. About 90% of the average annual discharge occur in the four month period from December to March and mean annual runoff(MAFSWMA /AREASWMA) from SWMAs vary from 70 mm to 470 mm. In the arid zone the yearly variability is high to very high. The mean annual runoff from SWMAs is very small, and varies between 0.1 and 5 mm.

Available Resource

The total annual divertible yield of the 40 SWMAs is approximately 55,900 GL or approximately 74% of the total mean annual flow. It should be noted that divertible Yield was based on median annual flow, which is generally lower than the mean annual flow. The remaining 26%, has limited development potential due to salinity (tidal) or environmental flow requirements for National Parks (eg. SWMAs 819, 820 and 821). Quoted annual divertible yield does not account for environmental water requirements outside National Parks.

Sustainable yield is defined as the maximum volume of water that can be diverted after taking account of all environmental water requirements. In the NT this requirement has been set, for the interim, at 80% of the Divertible Yield in the humid zone, and 95% in the arid zone. The total sustainable yield is approximately 11,100,000 ML or approximately 15% of the total mean annual flow.

The SWMA with the most highly developed surface water resource is 815.A (Darwin / Blackmore Rivers), with a developed yield of 38.2 GL. This represents about 72% of the total developed yield in the NT.

Map of mean annual run-off Map of mean annual run-off
Basin/Surface Water Management AreaMean Annual Run-off (GL/yr)% of stateNatural mean annual out-flow (GL/yr)In-flow (GL/yr)
Adelaide River 1,8802.491,8800
Barkly 600.800
Bathurst and Melville Islands 3,1004.113,1000
Blyth River 1,8402.441,8400
Buckingham River 2,8003.712,8000
Burt 20.0300
Calvert River 9401.259400
Daly River 6,7408.946,7400
Darwin / Blackmore Rivers 440.583400
East Alligator River 6,8709.116,8700
Finke River (NT) 164.22no data0
Finniss / Elizabeth / Howard Rivers 2,6803.552,6800
Fitzmaurice River 1,5001.991,5000
Georgina River (NT) 2,4873.32,4870
Goomadeer River 1,3001.721,3000
Goyder River 1,6852.231,6850
Groote Eylandt 680.96800
Hay River (NT) 146.19no data0
Keep River (NT) 510.68720210
Koolatong River 1,7602.331,7600
Limmen Bight River 1,5702.081,5700
Liverpool River 4,2605.654,2600
Mackay (NT) 22.0300
Mary River 2,1802.892,1800
McArthur River 3,2704.343,2700
Moyle River 600.86000
Nicholson River (NT) 674.896740
Ord River (NT) 8301.18300
Robinson River 9601.279600
Roper River 5,5407.345,5400
Rosie River 500.665000
Settlement Creek (NT) 8301.18300
South Alligator River 5,7507.625,7500
Todd River 86.1100
Towns River 540.725400
Victoria River 4,5406.024,5400
Walker River 3,5004.643,5000
Warburton (NT) no data no data0
Wildman River 8151.088150
Wiso 8201.0900

How saline are Northern Territory's surface water resources?

Table: Surface water resource by salinity class for divertible yield (GL)

Surface Water Managemnet Area<500 mg/l (GL/yr)500 - 1500 mg/l (GL/yr)1500 - 5000 mg/l (GL/yr)5000 -14000 mg/l (GL/yr)>14000 mg/l (GL/yr)Total volume (GL/yr)
Northern Territory111,827no datano datano datano datano data
Adelaide River 2,960no datano datano datano data1,480
Barkly 1,200no datano datano datano data600
Bathurst and Melville Islands 5,400no datano datano datano data2,700
Blyth River 2,600no datano datano datano data1,300
Buckingham River 4,400no datano datano datano data2,200
Burt 39no datano datano datano data20
Calvert River 1,780no datano datano datano data890
Daly River 11,120no datano datano datano data5,560
Darwin / Blackmore Rivers 704no datano datano datano data352
East Alligator River 5,720no datano datano datano data2,860
Finke River (NT) 328no datano datano datano data164
Finniss / Elizabeth / Howard Rivers 4,800no datano datano datano data2,400
Fitzmaurice River 2,840no datano datano datano data1,420
Georgina River (NT) 4,974no datano datano datano data2,487
Goomadeer River 2,300no datano datano datano data1,150
Goyder River 3,028no datano datano datano data1,514
Groote Eylandt 1,300no datano datano datano data650
Hay River (NT) 292no datano datano datano data146
Keep River (NT) 780no datano datano datano data390
Koolatong River 3,160no datano datano datano data1,580
Limmen Bight River 2,980no datano datano datano data1,490
Liverpool River 5,680no datano datano datano data2,840
Mackay (NT) 44no datano datano datano data22
Mary River 3,880no datano datano datano data1,940
McArthur River 6,340no datano datano datano data3,170
Moyle River 1,080no datano datano datano data540
Nicholson River (NT) 1,348no datano datano datano data674
Ord River (NT) 1,660no datano datano datano data830
Robinson River 1,800no datano datano datano data900
Roper River 9,560no datano datano datano data4,780
Rosie River 900no datano datano datano data450
Settlement Creek (NT) 1,620no datano datano datano data810
South Alligator River no datano datano datano datano datano data
Todd River 172no datano datano datano data86
Towns River 1,020no datano datano datano data510
Victoria River 5,600no datano datano datano data2,800
Walker River 6,600no datano datano datano data3,300
Warburton (NT) no datano datano datano datano datano data
Wildman River 178no datano datano datano data89
Wiso 1,640no datano datano datano data820

How much of Northern Territory's surface water resource has been developed?

Currently only two major water-supply systems use surface water in the NT. Darwin is supplied from Darwin River Dam (259 GL capacity). The town of Katherine is supplied from a weir on Katherine River.

Map of developed yield of surface water management areas Map of developed yield of surface water management areas

How committed are Northern Territory's surface water resources?

All the Surface Water Management Areas are in development category 1, except for the Darwin / Blackmore River Management Area (815.A), which is in category 2. There are no over-developed management areas in the Territory. About 99% of the sustainable yield is undeveloped.

Map of NT's surface water development status Chart of Surface Water Management Areas development status
Basin/SWMAVolume diverted (GL/yr)Sustainable (GL/yr)Diversion Development class
Adelaide River 2290LOW DEVELOPMENT
Barkly 130LOW DEVELOPMENT
Bathurst and Melville Islands 1588LOW DEVELOPMENT
Blyth River 0220LOW DEVELOPMENT
Buckingham River 0440LOW DEVELOPMENT
Burt 14LOW DEVELOPMENT
Calvert River 1180LOW DEVELOPMENT
Daly River 81,110LOW DEVELOPMENT
Darwin / Blackmore Rivers 3670MEDIUM DEVELOPMENT
East Alligator River 0900LOW DEVELOPMENT
Finke River (NT) 18LOW DEVELOPMENT
Finniss / Elizabeth / Howard Rivers 1480LOW DEVELOPMENT
Fitzmaurice River 1280LOW DEVELOPMENT
Georgina River (NT) 1125LOW DEVELOPMENT
Goomadeer River 0490LOW DEVELOPMENT
Goyder River 0303LOW DEVELOPMENT
Groote Eylandt 3130LOW DEVELOPMENT
Hay River (NT) 17LOW DEVELOPMENT
Keep River (NT) 178LOW DEVELOPMENT
Koolatong River 0310LOW DEVELOPMENT
Limmen Bight River 1300LOW DEVELOPMENT
Liverpool River 0570LOW DEVELOPMENT
Mackay (NT) 12LOW DEVELOPMENT
Mary River 1400LOW DEVELOPMENT
McArthur River 1630LOW DEVELOPMENT
Moyle River 0110LOW DEVELOPMENT
Nicholson River (NT) 1134LOW DEVELOPMENT
Ord River (NT) 1166LOW DEVELOPMENT
Robinson River 1180LOW DEVELOPMENT
Roper River 1950LOW DEVELOPMENT
Rosie River 190LOW DEVELOPMENT
Settlement Creek (NT) 1160LOW DEVELOPMENT
South Alligator River 0no dataLOW DEVELOPMENT
Todd River 14LOW DEVELOPMENT
Towns River 0100LOW DEVELOPMENT
Victoria River 2560LOW DEVELOPMENT
Walker River 0660LOW DEVELOPMENT
Warburton (NT) 0no dataLOW DEVELOPMENT
Wildman River 060LOW DEVELOPMENT
Wiso 140LOW DEVELOPMENT

The volume diverted is the total volume of the SWMA's surface water resources diverted for use both within the management area and for export to other management areas.

A four-class classification system was developed to provide a simple method to communicate the status of the use and allocation of Australia's water resources in relation to sustainable water management.

It is important to recognise that adequately quantifying a sustainable flow regime or sustainable yield and consequent operating rules is a complex matter. State, Territory and scientific agencies continue to develop and apply methods and measures for determining sustainable flow regimes and sustainable yields.

This categorisation provides a general guide only. Please refer to the State and Territory Overview and Technical reports for detail on the analysis methods used.

CategoryDevelopment status
1<30%Low development
230 - 70%Moderate development
370 - 100%Highly developed
4100%Overdeveloped

* Water use as a percentage of sustainable flow regime (surface water) and sustainable yield (groundwater)

How much groundwater does Northern Territory have?

Hydrology

The principal groundwater resources in the NT are contained in fractured rock aquifers of Palaeozoic and Pre Cambrian age and porous Tertiary/Cretaceous sediments. Bore yields are typically less than 2 L/s but higher yields occur in several provinces. Of note in this regard are the widespread fractured and cavernous Cambrian limestones of the Daly, Wiso and Georgina Basins and the porous and fractured Palaeozoic sandstones of the Amadeus Basin.

Recharge is generally related to the north to south rainfall distribution across the NT. In the higher rainfall areas of the north (>800mm/year), recharge is relatively high and occurs regularly each year. In the low rainfall areas of the south recharge are very low and occur infrequently. This is obviously the major influence on reliability and long term sustainability of groundwater supplies.

Available Resources

The available groundwater resource is defined to be the amount of groundwater that is renewable or recharging the systems. Across the different aquifer systems of the NT this volume totals approximately 13,000 GL annually.

Generally to determine aquifer recharge, the NT was subdivided into 4 zones based on the likely dominant mechanism of recharge.

Recharge Zone 1 was considered to have distributed recharge over the catchment. Recharge Zone 2 - recharge from upper catchment rivers and creeks with some distributed recharge over parts of the catchment. Recharge Zone 3 - recharge from ephemeral lakes, floodouts, creeks and rivers. Recharge Zone 4 - recharge from floodouts, creeks and rivers.

Within the zones the probable recharge rates (ML/Ha/year) ranged from 0.2 to 5 ML/Ha/year in the northern most zone to 0.02 to 2.5 ML/Ha/year in the southern most zone. The range of recharge mechanisms and rates combine to reflect relatively higher annual recharge in the north to lower and infrequent recharge in the south. The rate applied to the GMUs and UAs was based upon the level of understanding of the GMU/UA.

An estimate of the percentage of the total GMU/UA area that receives recharge was also made again based on the level of understanding of the GMU/UA. The annual GMU/UA groundwater recharge volume, or available groundwater resource, was determined by multiplying the probable recharge rate by the estimated recharge area.

The areas of greatest potential for use, if considered only with respect to the amount of available groundwater, are those with the highest estimated recharge rates. These areas are naturally in the northern most part of the NT where the rainfall is highest and where the rock types are favourable for recharge. They include limestone aquifers of the Pine Creek Groundwater Province, the Daly River Groundwater Province  and the McArthur Groundwater Province and sedimentary aquifers of the McArthur Groundwater Province , the Melville Groundwater Province , the Bonaparte Groundwater Province , the Pine Creek Groundwater Province and the Arafura Groundwater Province.

Across the NT the average depth to the aquifer varies from 5 to 80m. Predominantly across the northern region the depth is less than 20m. In the Wiso, Amadeus, Ngalia, Georgina and Great Artesian Groundwater Provinces, which comprise approximately 30% of the NT, the depth is greater than 50m. Through the west-southwest of the NT the depth is predominantly between 20 and 50m. No relationship exists between the depth to the aquifer and the usage of groundwater because most groundwater is used for public or pastoral water supplies.

Sustainable Yield and Environmental Allocation

In the humid zone, the Sustainable Yield is estimated as 20% of the Divertible Yield, and in the arid zone it is estimated as 5%.

The sustainable yield of an aquifer system in the NT for the Audit has been defined by DLPE as 50% of the average annual aquifer recharge. Effectively this is stating that of the available groundwater resources, 50% is required to be allocated to sustain groundwater dependent ecosystems. The sustainable yield of the NT's groundwater resources is approximately 6,500 GL/year. Considering the annual use of groundwater, approximately 2% of the sustainable yield is being utilised.

Currently, without further scientific knowledge, the groundwater requirements of the environment can not be determined with greater confidence or accuracy. To narrow this gap in knowledge, the NT is undertaking 5 projects as part of the National River Health Program - Environmental Flows Initiative. The details of these projects are mentioned in the Environmental Water Requirements section.

Map of sustainable yield (GL/yr) of groundwater provinces

How committed are Northern Territory's groundwater resources?

Table: Allocation volumes (GL/yr in each development category)

Note: "GMU"=Groundwater Management Unit "UA"=Unallocated Area

ProvinceOverHighMedLowTotal (GL/yr)
AmadeusGMU14no datano data014
UAno datano datano data22
ArafuraGMUno datano datano datano datano data
UAno datano datano data11
AruntaGMU14no data05
UAno datano datano data33
BonaparteGMUno datano datano data22
UAno datano datano data11
Daly RiverGMUno datano datano data11
UAno datano datano data11
GeorginaGMUno datano datano datano datano data
UAno datano datano data99
Great ArtesianGMU9192911,017
UAno datano datano datano datano data
Halls CreekGMUno datano datano data77
UAno datano datano datano data0
McarthurGMUno data12no datano data12
UAno datano datano data22
MelvilleGMUno datano datano datano datano data
UAno datano datano datano data0
MusgraveGMUno datano datano data00
UAno datano datano data11
NgaliaGMUno datano datano datano datano data
UAno datano datano data11
Ord-VictoriaGMUno datano datano data00
UAno datano datano data66
Pine CreekGMUno datano datano data1212
UAno datano datano data55
TanamiGMUno datano datano data00
UAno datano datano data11
Tennant CreekGMUno datano datano datano datano data
UAno datano datano data11
WisoGMUno datano data3no data3
UAno datano datano data22

A four-class classification system was developed to provide a simple method to communicate the status of the use and allocation of Australia's water resources in relation to sustainable water management.

It is important to recognise that adequately quantifying a sustainable flow regime or sustainable yield and consequent operating rules is a complex matter. State, Territory and scientific agencies continue to develop and apply methods and measures for determining sustainable flow regimes and sustainable yields.

This categorisation provides a general guide only. Please refer to the State and Territory Overview and Technical reports for detail on the analysis methods used.

CategoryDevelopment status 
1<30%Low development
230 - 70%Moderate development
370 - 100%Highly developed
4100%Overdeveloped
Chart of Yield (%) In Each salinity class

Table: Groundwater resource by salinity class

Province<1500 mg/l (GL/yr)5000 mg/l (GL/yr)14000 mg/l (GL/yr)>14000 mg/l (GL/yr)Total volume (GL/yr)
Northern TerritoryGMU105173981882084254
UA56919181767593241351407092009369
AmadeusGMU13,848no data30no datano data
UAno datano data7920no data
ArafuraGMUno datano datano datano datano data
UA121no datano datano datano data
AruntaGMUno data511no datano data
UAno datano data28117no data
BonaparteGMUno datano data123no datano data
UA1,140no datano data2no data
Daly RiverGMU27,053no datano datano datano data
UA623no datano datano datano data
GeorginaGMUno datano datano datano datano data
UAno datano data172no datano data
Great ArtesianGMU187,400327904130
UAno datano datano datano datano data
Halls CreekGMUno data218no datano datano data
UAno data1no datano datano data
McarthurGMU12,150no datano datano datano data
UA2,349no datano datano datano data
MelvilleGMUno datano datano datano datano data
UA246no datano datano datano data
MusgraveGMUno datano data139no data
UAno datano data25no datano data
NgaliaGMUno datano datano datano datano data
UAno datano data84no data
Ord-VictoriaGMUno data10291no datano data
UA35119no datano datano data
Pine CreekGMU52,122no datano datano datano data
UA866no datano datano data6
TanamiGMUno datano data25no data95
UAno data1915no datano data
Tennant CreekGMUno datano datano datano datano data
UAno data29no datano datano data
WisoGMUno data6no datano datano data
UAno data111no datano datano data

How much water does Northern Territory trade?

The Total reported Volume Traded in Northern Territory is 0 GL; in 0 transactions.

The State and Territory water management agencies continue to consider water use efficiency and optimisation strategies within existing infrastructure (e.g. water supply efficiency, precision irrigation and scheduling, water recycling, trading and pricing) as part of water resource development planning.

Recognising that water is a finite resource, the States and Territories have developed water allocation systems where security and reliability are assigned to entitlement, trading is provided so water can be moved to high value uses and the choices of individuals are maximised.

Part of the decision-making framework to enable and facilitate water trading, changes in water allocation and definition of rights to water is the need for water use monitoring. Water use monitoring will assist decision-making and provide an opportunity over time to evaluate the effectiveness of allocation policies.

Environmental water requirements

In the absence of rigorous scientific assessment basis, environmental flow requirement is assumed to be 80% of the Divertible Yield (median annual flow) in the Humid Zone and 95% in the Arid Zone.

Catchment wide management decisions impacting on flow regimes can lead to unintended consequences for the environment. The provision of water for existing and potential water resource demands, both surface and groundwater, and associated infrastructure should be implemented in a manner consistent with nationally agreed policy frameworks relating to the ecologically sustainable management of water resources.

Underpinning ecologically sustainable management is scientific knowledge on water requirements of ecosystems (ie timing, quantity and quality). Across the humid, arid and semi-arid regions of the NT the paucity of scientific knowledge on water requirements of ecosystems is acknowledged.

As part of the National River Health Program - Environmental Flows Initiative, the NT is undertaking 5 projects to assist in the establishment of environmental flow requirements for aquatic ecosystems (including flood plains and ecosystems). These projects are concentrated in the Daly River Basin and their title and aims are detailed below:

Modelling Dry-season Flows and Predicting the Impact of Water Extraction on a Flagship Species

The aim of this project is to provide recommendations on environmental flows consistent with maintaining the biota of the Daly River, given the competing demands of agriculture, recreation and tourism, conservation and Aboriginal culture.

Inventory and Risk Assessment of Water Dependent Ecosystems in the Daly Basin

The aim of this project is to provide a mapping-base for further assessment of water-dependent ecosystems in the Daly basin. This will be done through remote sensing and GIS and will allow overlaying of further information sets, such as land use and water management structures that may affect the water dependent ecosystems. Threats to these ecosystems from forecast and existing water use and land management practices will be established and those ecosystems most at risk will be identified.

Environmental Flow Requirements of Vallisneria nana

This project will map the distribution, dimensions and performance of key habitat patches of Vallisneria nana and record and analyse associated hydraulic parameters. The habitat preferences of Vallisneria and dependent macroinvertebrate fauna will allow predictions of the response of these species to altered flow. Importantly, the interaction between these two ecological components will be investigated as part of furthering environmental flow assessment methods and understanding of the requirements of different biota.

Water requirements for riparian vegetation

Effect of reduced dry season flow on phytoplankton and periphyton

For the Daly catchment, the projects will develop information to increase the understanding of the need to maintain environmental flows and for a rational basis for the determination of sustainable water use, considering all commercial and non-commercial values of the region. This will include a well-supported example of the consequential effects of flow alteration on the biology of a key element of the Daly River's fauna.

At the NT level, the project outcomes will assist to improve the scientific basis for decisions underpinning the move to sustainable management of water resources under the principles set out by the COAG Water Reform Framework, National Principles for the Provision of Water for Ecosystems (ARMCANZ and the Australian and New Zealand Environment Conservation Council) and the National River Health Program Strategy - Environmental Flows Initiative.

Further information

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