Water - Northern Territory - Water Resources Overview
Surface and Groundwater Management, Availability, Allocation and Efficiency of Use
Northern Territory Water Resources Overview
Introduction
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.
Legislative Framework
The Department of Lands, Planning and Environment (DLPE) has responsibility for the management of water resources under the provisions of the NT Water Act 1992 and Regulations. The Act and regulations provides for the investigation, use, control, protection, management allocation and administration of water resources and applies across the NT. As the single statutory framework for all aspects of water resource management, they are used to implement Integrated Catchment Management and Integrated Resource Management as well as providing the means for comprehensive allocation and entitlement systems. Additionally, they are the statutory means whereby the National Water Quality Management Strategy is implemented.
The Minister for DLPE is responsible to Parliament for the effective administration of the Act. The Minister appoints a Controller of Water Resources who has the responsibility for day to day administration of the Act and Regulations.
COAG Compliance
In its 1994 communique the Council of Australian Governments (COAG) agreed:
That action needs to be taken to arrest widespread natural resource degradation in all jurisdictions occasioned, in part, by water use and that a package of measures is required to address the economic environmental and social implications of future water reform; To implement a strategic framework to achieve an efficient and sustainable water industry.
Such widespread degradation of water resources, however, has not occurred in the NT. Through the COAG Water Reform Framework the NT recognises the opportunity to develop its water resources in an economic, ecological and sustainable manner thus avoiding the natural resource degradation experienced elsewhere in the country.
The NT's Policy with respect to the COAG Water Reform Framework is summarised below:
In relation to water allocations or entitlements:
- Water allocation systems will be provided at regional scale in the form of declared allocation (or share) of assessed water resources to beneficial uses (environmental values in the National Water Quality Management Strategy).
- Entitlements are provided in the form of licences under the Water Act to take surface water or groundwater.
- All surface water extraction must be licensed; with the exception of domestic and stock bores, all bore extractions exceeding 15 L/sec must be licensed and all bores in declared groundwater management areas must be licensed.
- Surface water and groundwater extraction licences are granted within assessed sustainable yield of regional water resources.
- All licences specify ownership and limits to extraction volume (but do not specify reliability, transferability or quality), and trading is possible in Water Control Districts.
- The NT is working to implement the National Principles for Providing Water for Aquatic Ecosystems; both through the formulation of regional water allocation plans and in research to establish scientific methods to determine environmental water requirements.
In relation to trading in water allocations or entitlements:
- Water allocations will not be tradeable in the NT since they will take the form of formally declared regional plans. Trading arrangements for licences (entitlements) are currently being developed in consultation with water users and, following minor changes to Regulations under the Water Act, will result in trade being possible.
In relation to the environment:
- Beneficial Use declarations continue under the Water Act in accordance with the National Water Quality Management Strategy.
- Waste discharge licensing, monitoring programs and development of catchment management strategies proceed from Beneficial Use declarations
- Landcare and Waterwatch groups are expanding throughout the NT and are associated in many cases with river and stream protection.
Water Industry Structure
The DLPE has responsibility for the planning and management of land use to promote and ensure sustainable development. The department administers natural resource legislation related to the management of water, land and soil resources, land use planning, and the specific management of land leased for pastoral purposes. The DLPE also gauges the environmental impact of designated developments and seeks development approvals under Environmental Impact Assessment legislation. Through the NT Water Act 1992, the Natural Resources Division of DLPE is responsible for the investigation, use, control, protection, management allocation and administration of water resources.
The Power and Water Authority (PAWA) is the largest water utility in the NT. It supplies water to the major urban centres, smaller regional centres and remote communities across the NT. Water is sourced either from surface storages, rivers or groundwater. PAWA's water sources for domestic and industrial supplies for the NT's major population centres include:
Darwin - Darwin River Dam (90%), McMinns' Borefield (10%)
Tennant Creek, Alice Springs, Yulara - Borefield supplies
Katherine - Borefield (40%) and river supply (60%)
Also across the NT, small private water supplies are operated by mining and pastoral companies, local development associations and the Aboriginal and Torres Strait Island Commission.
Surface Water Resource
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.
Figure 1: Surface Water Management Areas
Hydrology
The mean annual flow (MAF) of all NT SWMAs is 75,400,000 ML. 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 70mm to 470mm. In the arid zone the yearly variability is high to very high. The mean annual runoff from SWMAs is very small, and vary between 0.1 and 5mm.
Available Resource
The total annual divertible yield of the 40 SWMAs is approximately 55,900,000 ML 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 38,200ML. This represents about 72% of the total developed yield in the NT.
Developed Use and Allocation
The total annual volume of surface water licensed for use in the NT is 52,500 ML. These licences have been issued for urban and rural water supplies, irrigation, aquaculture, and mining. For the Audit, the set limit on surface water extraction licences and entitlements have been reported as allocations.
At present, about 50,700 ML of surface water is used in the NT annually. This represents 0.46% of the sustainable yield of the resource.
Surface water use in NT is dominated by urban water supply, which use approximately 74% of total extracted water on average each year. Rural water supply accounts for 5%, Irrigation use accounts for 12% of total use and the cattle industry consumes approximately 6%. The remainder is consumed primarily for mining activities, and aquaculture. Most of the land under irrigation using surface water is located in Katherine River floodplain area within Daly River SWMA 814.
Water Supply Systems
Currently there are only two major water supply systems that use surface water in the NT. Darwin is supplied from Darwin River Dam (259,000 ML capacity). The town of Katherine is supplied from a weir on Katherine River.
Categorisation
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.
The percentage of management areas in each 'development' category is summarised in Table 1.
Table 1 Summary of Surface Water Management Areas (SWMA) 'Development' Categories
| Category Description | Number of SWMAs (%) |
|---|---|
| Low Level Resource Development (0-30%) | 39 (98) |
| Medium Level Resource Development (30-70%) | 1 (2) |
| High Level Resource Development (70-100%) | Nil |
| Over Developed Resource (>100%) | Nil |
The total volume of undeveloped water (sustainable yield less the total annual use) available for development is 11,000,000ML. Thirty-nine SWMAs in the NT have water available for development.
Figure 2: SURFACE WATER MANAGEMENT AREAS, DEVELOPMENT CATEGORIES 
Groundwater Resource
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 ÒWater Control DistrictsÓ. 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. The boundaries for these units are shown in Figure 3. Figure 3:GroundWater Management Units 
Hydrogeology
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 Resource
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 13,000,000 ML annually.
Generally to determine aquifer recharge, the NT was subdivided into 4 zones based on the likely dominant mechanism of recharge. These zones are shown in Figure4 Groundwater Recharge Zones.
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 (NT1, NT2, NT15, NT18), the Daly River Groundwater Province (NT3, NT22, NT24) and the McArthur Groundwater Province (NT28) and sedimentary aquifers of the McArthur Groundwater Province (NT8, NT27), the Melville Groundwater Province (NT9, NT10), the Bonaparte Groundwater Province (NT12), the Pine Creek Groundwater Province (NT17) and the Arafura Groundwater Province (NT21).
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.
Use of the Resource
Water supplies from groundwater resources have been developed to meet urban, rural domestic, pastoral, irrigated agriculture, mining, construction and aquaculture demands. In total, it is estimated that the annual use of groundwater in the NT is 144,000 ML.
Of the major population centres in the NT, Alice Springs and Tennant Creek rely entirely on groundwater, with Darwin and Katherine having ground and surface water supplies. Most all other smaller communities in the NT rely on groundwater supplies. Approximately 48,000 ML/year of groundwater is used for urban and industrial use. In rural areas where domestic production bores are the main source of water, approximately 8,500 ML/year is used. Regionally across the NT, the dominant use of groundwater is by the pastoral industry. Estimate of use based on cattle numbers is 23,500 ML/year. Irrigated agriculture and horticulture, which is predominantly in the Darwin and Katherine regions, uses approximately 47,000 ML/year. Use of groundwater by mines across the NT is estimated to be of the order of 17,000 ML/year, with the major user the Nabalco bauxite mine.
Data on water use is lacking in the NT. With the exception of borefield production figures from the water utility - the Power and Water Authority and Nabalco. It is recognised that improvements in metering or monitoring of groundwater use are required. As such, the above quoted estimates have been made from a variety of indirect means including crop area and per hectare use estimates, cattle stocking numbers and estimates of bore numbers and average rural domestic use.
Sustainable Yield and Environmental Allocation
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 6,500,000 ML/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.
Categorisation
Of the 8 Groundwater Management Units, 2 are abstraction category 4, 1 is abstraction category 3, and 5 are abstraction category 2. The remaining 46 Unincorporated Areas are abstraction category 1.
The percentage of management areas in each 'abstraction' category is summarised in Table 2.
Table 2. Summary of GMUs and GMUs + UAs 'Abstraction' Categories
| Category Number | Category Description | Number of GMUs (%) | Number of GMUs+UAs (%) |
|---|---|---|---|
| Low Level Resource Abstraction | 0 | 46 (85) | |
| Medium Level Resource Abstraction | 5 (64) | 5 (9) | |
| High Level Resource Abstraction | 1 (12) | 1 (2) | |
| Over Abstracted Resource | 2 (24) | 2 (4) |
The over-abstracted management units are NT6 (Mereenie Sandstone aquifer which is the town water supply for Alice Springs) and NT7 (Alice Springs town basin aquifer which is being deliberately over- abstracted to manage a rising water table).
Regional groundwater allocation plans have only been prepared for three GMUs and these are currently under review. Entitlements to groundwater however are provided for through the NT Water Act 1992 by a formal extraction licence or a riparian entitlement for domestic or pastoral use. Although the NT Water Act 1992 has provision for the licensing of all bores with yield greater than 15 L/s anywhere in the NT and for all bores within a Water Control District the issuing and enforcement of such licensing has been predominantly limited to the southern region. Extraction licences have been issued to Power and Water Authority for urban water supplies in Darwin, Tennant Creek and Alice Springs, and Nabalco for mining and urban water supply. Several licences have also been issued in Darwin, Ti-Tree and Alice Springs for irrigation and horticultural supplies, mainly associated with the larger developments. As such the allocation categories for the GMUs/UAs reflect the level of groundwater extraction licences issued and recognition of riparian entitlements.
Based on the above definition, 2 GMUs are allocation category 4, 2 are category 3, 1 is category 2 and 3 are category 1. The remaining 46 Unincorporated Areas are allocation category 1.
The percentage of management areas in each 'allocation' category is summarised in Table 3.
Table 3.Summary of GMUs and GMUs + UAs 'Allocation' Categories
| Category Number | Category Description | Number of GMUs (%) | Number of GMUs+UAs (%) |
|---|---|---|---|
| Low Level Resource Allocation | 3 (40) | 49 (90) | |
| Medium Level Resource Allocation | 1 (12) | 1 (2) | |
| High Level Resource Allocation | 2 (24) | 2 (4) | |
| Over Allocated Resource | 2 (24) | 2 (4) |
The over-allocated management units are NT6 and NT7 as described above.
Figure 5: Abstraction categories, Groundwater Management Units 
Figure 6: Allocation category, Groundwater Management Units 
Joint Groundwater and Surface Water Use
The current major joint groundwater and surface water use schemes are Water Supply for Darwin and greater Darwin area, and Katherine Town. The type of connectivity between the surface water and groundwater resources is Physical as well as Policy/Management.
There is likely to be no potential major joint schemes. However there is potential for many minor joint schemes for agriculture, and cattle industry within a SWMA, and the type of connectivity between the resources is only Policy/Management.
Potential for Development
Demand Trends
Urban water demand depends on two major variables: population growth rates and water consumption per head of population, both of which would greatly affect the demand in Darwin and greater Darwin areas. Using data assembled as part of this audit, urban water demand was projected over 50 years to the year 2050. Based on these projections it is expected that Darwin water use would increase from 37,300ML/yr to 126,130ML/yr. This was based on a growth rate of 2.3%. The growth rate in Alice Springs, Katherine, and other towns would also increase the water demand.
As mentioned previous, the prediction of future irrigation water use is extremely difficult. From the figures provided by the O.R.D. the demand trend for irrigated agriculture is for growth at a rate of 10% through to 2020. For this trend to occur through to 2020, areas outside of the current established management units will have to be utilised as available groundwater is limiting. This is just one of many factors which will influence the growth of the irrigated agricultural industry and hence the future demand for groundwater.
Development Constraints
The main constraints on the development of the NT's water resources are associated primarily with infrastructure. The cost to establish infrastructure in the NT is generally higher relative to the rest of Australia due to factors associated with isolation, transport and power. Also as the level development of water supply infrastructure is generally low, use of existing infrastructure is limited which can add to the costs of water supplies.
As the level of development of the NT's water resources is relatively low, the advantages in terms of available water are obvious. However, as a constraint this can mean a lower level of detailed knowledge and understanding of the water resource. In some cases this can translate to added costs for a developer or industry to investigate and evaluate the capability of a suitable water resource, be it surface water or groundwater.
The seasonal nature of rainfall also poses added challenges and possible constraints to the development of surface water supplies. With approximately 90% of the average annual discharge occurring between December and March in the humid zone, the ability to capture or divert water and store it are the primary concerns.
With respect to groundwater resources, the ability to develop appropriate groundwater supplies for intensive development can pose a constraint. Although this audit indicates that there are significant groundwater resources, there are constraints related to the location of aquifer systems suitable for development of high yielding production bores or borefields required for intensive developments such as horticulture.
The water requirements of the environment, environmental flows and groundwater dependent ecosystems, can also be perceived as a constraint on development. For the Audit, the NT has generalised this requirement, however there may be some SWMAs and or GMUs/UAs where the determined amount of water for the environment is limiting for development.
Development Potential
Several potential dam sites have been identified for water supply, recreation, and flood mitigation purposes. Some of the sites have been analysed in terms of hydrology, while others are just sites where topography is suitable for storage purposes. Table 4 gives details of some of the potential dams where hydrological studies have been done without consideration for environmental flow requirement. Most of these dam sites are alternative sites for a future water supply source. Suitable soils for agriculture and horticulture exist in the humid zone. There is potential for development of off-stream storages, as well as run-of river extraction especially in Daly, Finniss, Adelaide, Victoria and Roper basins.
Table 4: SUMMARY OF POTENTIAL DAMS
| Dams | Estimated Safe Yield (ML/Annum) |
Capacity ML |
||
|---|---|---|---|---|
| Warrai Dam | 67,000 | Water Supply | Adelaide River | 780,000 |
| Marrakai Dam | 508,000 | Water Supply | Adelaide River | 2,800,000 |
| Acacia Gap Reservoir | 32,000 | Water Supply | Manton River | 112,000 |
| Mt.Bennet Reservoir | 175,200 | Water Supply | Finniss River | 700,000 |
| Pine Creek Dam No.15 | 650 | Water Supply | u/s of McKinlay River | 1,800 |
| Upper Manton Dam | 8,500 | Water Supply | Manton River | 41,000 |
| McAddens Dam No.3 | 11,700 | Water Supply | McAddens Creek | 50,000 |
| Dorothy Dam No.1 | 5,600 | Water Supply | Dorothy Creek | 24,500 |
Considering 2% of the NT's total sustainable groundwater resources are currently being utilised, the potential for development is high. However, when considering other factors such as environmental values, potential users, existing support infrastructure, land capability, population and heritage issues, this potential is reduced. Seven GMUs are associated with the NT's main population centres and the eighth a major bauxite mine. NT1, NT5 and NT8 are considered to have medium development potential. NT1 and NT5 have both potential demand and available resources for development. The potential in the case of NT8 is due to an expected decline in current use making more water available for other uses in the future.
Two GMUs, NT6 and NT7 are currently being mined. NT6 is the major water supply for Alice Springs and will continue to be utilised whilst it is considered economical. A new borefield still exploiting the Mereenie Sandstone, which will shift the pumping centre away from the current Roe Creek borefield, is being considered. NT7 is an alluvial basin underlying urban Alice Springs and water levels are being managed to reduce the mobilisation of salts into the aquifer to reduce adverse infrastructure impacts.
So far as the remaining 98.8% of the NT which is Unincorporated, the development potential varies. Areas can be identified which are more prospective for significant regional development. With associated supporting infrastructure, potential users and population the development potential for these areas would be considered to be good.
Overall, it is considered that the main opportunity for development exists for water supply and horticultural industry, through the development of high return, niche market crops.
Forecast Use
Predicted use in 2020 and 2050 has been estimated primarily from figures provided by the NT Office of Resource Development (O.R.D.). Considering the current use types, projections of growth were made for urban, rural and irrigation use. Future urban use was based on population growth projections, rural use on population growth and cattle stocking rate projections and irrigation use on projections of horticultural growth. The growth projections were made on a regional basis and applied to current levels of use in the specific areas to determine 2020 and 2050 average volumes of use.
Current and predicted population figures were obtained from the NT Treasury Department and the Australian Bureau of Statistics for statistical local areas and towns across the NT. Percentage growth rates were determined from these figures and applied to current urban use volumes for the main population centres in the 8 GMUs. These same population growth rates were applied to the current rural domestic use volumes. Annual growth rates to 2020 ranged from 2.3% for Darwin to 0.8% for Alice Springs. Negative growth rates of 2.2% and 0.3% for Tennant Creek and Nhulunbuy reflected those towns' reliance on mining. 2020 to 2050 annual growth rates ranged from 1.6% for Darwin to 1.1% for the rest of the NT.
Figures for cattle populations from O.R.D. indicate that growth in this industry will occur mainly in the northern region of the NT. With predicted annual growth rates in this region ranging from 0.6 to 3.2 % cattle numbers are predicted to rise from their current 745,000 to 870,000 in 2020 to 1,065,000 in 2050. In the southern region the annual growth rate ranges from 0 to 0.4 % with respective cattle numbers of 820,000, 850,000 and 900,000.
The only other significant water user in the NT is the irrigated agricultural industry. It was also the most difficult sector in which to obtain figures of forecast growth and associated water use. This was mainly due to the relatively early stage of development of irrigated agriculture and horticulture in the NT, and the difficulty therefore of predicting growth where there is currently little or no development and scant historical water use records. The O.R.D. predictions are based on estimates and surveys of current crop areas and their knowledge of potential areas for development. Consideration of future markets was also factored in to their predictions. The main areas in the NT for irrigated agriculture or horticulture development are the Darwin, Katherine, Ti-Tree and Alice Springs regions. To 2020 annual growth rates of around 10% are predicted for all these regions. Beyond to 2050 an annual growth rate of 1% is predicted.
The above figures were the basis upon which the forecast uses in 2020 and 2050 were made, and hence the abstraction categories for the 8 GMUs.
Categorisation in 2020 and 2050
A summary of the SWMA and GMU categories is provided in the two tables below.
Table 5. GMU Abstraction Category for 2020 and 2050.
| GMU No. | Year 2020 Abstraction | Year 2050 Abstraction |
|---|---|---|
| NT1 | 2 | 4 |
| NT2 | 4 | 4 |
| NT3 | 4 | 4 |
| NT4 | 1 | 2 |
| NT5 | 4 | 4 |
| NT6 | 4 | 4 |
| NT7 | 4 | 4 |
| NT8 | 3 | 2 |
Table 6. SWMA Development Category for 2020 and 2050.
| SWMA No. | Year 2020 | Year 2050 |
|---|---|---|
| 001.NT | 1 | 1 |
| 005.NT | 1 | 1 |
| 006 | 1 | 1 |
| 007.NT | 1 | 1 |
| 023.NT | 1 | 1 |
| 026.NT | 1 | 1 |
| 027 | 1 | 1 |
| 028 | 1 | 1 |
| 029 | 1 | 1 |
| 809.NT | 1 | 1 |
| 810.NT | 1 | 1 |
| 811 | 1 | 1 |
| 812 | 1 | 1 |
| 813 | 1 | 1 |
| 814 | 1 | 1 |
| 815A | 2 | 2 |
| 815B | 1 | 1 |
| 816 | 1 | 1 |
| 817 | 1 | 1 |
| 818 | 1 | 1 |
| 819 | 1 | 1 |
| 820 | 1 | 1 |
| 821 | 1 | 1 |
| 822 | 1 | 1 |
| 823 | 1 | 1 |
| 824 | 1 | 1 |
| 825 | 1 | 1 |
| 826 | 1 | 1 |
| 901 | 1 | 1 |
| 902 | 1 | 1 |
| 903 | 1 | 1 |
| 904 | 1 | 1 |
| 905 | 1 | 1 |
| 906 | 1 | 1 |
| 907 | 1 | 1 |
| 908 | 1 | 1 |
| 909 | 1 | 1 |
| 910.NT | 1 | 1 |
| 912.NT | 1 | 1 |
| 929 | 1 | 1 |
Environmental Water Requirements
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:
1. 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.
2. 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.
3. 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.
4. Water requirements for riparian vegetation
5. 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.
Water Resource Management
Surface Water Management Initiatives
The NT is implementing a number of initiatives to encourage water users to manage their water in an environmentally sensitive way. The primary instrument is through the Beneficial Uses process. Water quality management in the Territory is controlled by the Water Act and in accordance with the National Water Quality Management Strategy. The term ÒBeneficial UseÓ is an indication of how the community and government want to manage and use the water in the catchment. Twenty Beneficial Uses have been declared mostly in the Top end Basins. Details are in Table 6. The Power and Water Authority of NT has developed Demand Management Plans, and short and long term Drought Management Plans that take into account environmental considerations. In terms of public education, the following initiatives are currently being developed.
- National Water Week - all relevant water authorities participate in National Water Week;
- Waterwise Program - covers water customers in major populated areas in NT;
- Waterwatch - community monitoring of water quality
Groundwater Management Initiatives
Specific initiatives being undertaken by the Natural Resources Division of DLPE with respect to the management of the NT's groundwater resources include:
- An NT wide assessment and mapping program to identify appropriate groundwater resources with significant regional development potential. Currently mapping has been completed or is in progress covering approximately 75% of the NT. This level of information is vital for effective planning for appropriate groundwater resource development.
- Groundwater database development to improve the management, use, analyses and dissemination of data and information to all users. The need to more effectively utilise existing groundwater data has resulted in investment in digital systems that enable greater access to and improved scope for analyses of data and information. As a result the ability to respond effectively to management issues is enhanced.
- Providing information to the public at an appropriate level in order to raise public awareness about groundwater. The NT has a groundwater page on the Department's web site which is aimed at providing educational material to the general public. The Division is also planning to provide hydrological and hydrogeological data, maps and information over the Internet. Specifically, water resource assessments have and are being undertaken for specific client groups such as the pastoral industry and aboriginal groups. An important aspect of these assessments is to provide a product which meets the needs of clients. This has resulted, in some cases, in multi-media packages of tailored maps, reports, databases and images being distributed on CD.
- Water bore driller licensing and bore construction standards are enforced to protect the integrity of the groundwater resources.
- A network of baseline groundwater resource monitoring is in place to provide for ongoing resource capability assessments.
- Integrated management of surface water and groundwater
- Groundwater Management Plans
| Basin 814, Daly River | Copperfield Creek & tributaries | Drinking Water; Aquatic Ecosystem Protection |
|---|---|---|
| Edith River & Tributaries | Aquatic Ecosystem Protection | |
| Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics; Agricultural Water Use | ||
| Katherine River Tributaries | Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics; Raw Water for Drinking Water Supply; Agricultural Water Use | |
| Katherine Region - ground waters | Raw Water for Drinking Water Supply, Agriculture and Industrial Purposes | |
| Basin 815A, Darwin/Blackmore Rivers | Darwin and Blackmore Rivers Catchment Area | Raw Water for Drinking Water Supply; Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics; Agricultural Water Use |
| Basin 815B, Finniss, Elizabeth and Howard Rivers | Hudson Creek and Tributaries | Aquatic Ecosystem Protection |
| Darwin Harbour and marine reaches of rivers and creeks draining into Harbour | Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics | |
| Fog Bay Area as defined in the Declaration | Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics | |
| Shoal Bay - Vernon Islands | Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics | |
| Crater Lake as defined in the Declaration | Recreational Water Quality; Aesthetics | |
| Rapid Creek - freshwater reaches | Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics | |
| Elizabeth and Howard Rivers Region - all Waterways including tributaries | Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics | |
| Elizabeth and Howard Rivers Region - Ground water | Raw Water for Drinking Water Supply and Agriculture | |
| Basin 817, Adelaide River | Howley Creek and Tributaries | Aquatic Ecosystem Protection |
| Coomalie Creek Catchment including Tributaries | Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics; Agricultural Water Use | |
| Basin 818, Mary River | Stock water; Aquatic Ecosystem Protection | |
| Stock water; Aquatic Ecosystem Protection | ||
| Aquatic Ecosystem Protection | ||
| Basin 901, Koolatong River | Gove Area as defined in the Declaration | Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics |
| Basin 907, McArthur River | McArthur River Area as defined in the Declaration | Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics |
| Basin 929, Groote Eylandt | Groote Eylandt Area as defined in the Declaration | Aquatic Ecosystem Protection; Recreational Water Quality; Aesthetics |
Key Management Issues
There are a number of key management principles for a sustainable water sector. The following discussion lists some of the important issues that face the NT.
- Investment in knowledge about the resource is an important issue. Ongoing resource capability assessment will lead to the definition of the quantity and quality of the resource as well as helping to define significant processes such as the interaction of surface water and groundwater. Continual investment will ensure that the latest information technology is used to generate, update and extend information. Sound information is required to underpin management decisions.
- Determination of the water requirements of ecosystems is the key to the ecologically sustainable management of water resources. Assessment work is required to provide the scientific knowledge base upon which groundwater dependent ecosystems can be identified and their water requirements estimated and also upon which environmental flow requirements can be determined.
- The goal of ecologically sustainable development of water resources must be enchanced by the community, industry and individuals.
- Regional Management Strategies need to be developed and implemented.
The Natural Resources Division has prioritised four main regions where Water Allocation Plans and Regional Management Strategies need to be developed: Darwin and surrounds, Katherine/Daly Region, Ti-Tree Basin and Alice Springs and surroundings. Together with the Water Reforms and requirements of the National Principles for the Provision of Water for the Environment (ANZECC 1996), the forecast increases in water use in these regions has driven the need for a consistent approach to managing water and incorporating environmental water requirements.
Data and Information Gaps
The search for knowledge and the continual striving for improvement will always result in a need for more data and information. Current topics where further research is required are:
- determination of environmental water requirements
- interaction of surface water and groundwater
- quantification of groundwater recharge and storage
- monitoring and determination of water use
The last decade has also seen a shift in focus from traditional water supply development activity to the identification of water resources with significant regional development potential.
Limited resources for gauging information will mean that data estimation techniques become more important. Appropriate technology to define these estimates will continually need to be improved and refined.
A water resources information environment is being developed to enable government, industry, and the community to have appropriate on-line access to data and associated information.
Future Directions
Water will continue to be vital to the NT. In determining future directions it is important that water be treated as a finite, renewable resource and that there is acknowledgment that it may become scarce. The value of water will continue to increase. The following goals and responses have been identified for the NT's water sector future.
- Continual building of our knowledge base to enable sustainable management of a finite resource. This goal will be achieved through the development of decision support systems, investment in appropriate upgraded information management modelling techniques and investment in new communication technology.
- The development of an efficient and equitable water allocation system to enhance social, economic and environmental well being. Water administration arrangements will be developed to reflect the value of the resource.
- Natural water resources will be protected to meet declared Beneficial Uses.
- More water will be made available through both existing resources and new sources and will contribute to sustainable development. Information on the incremental costs of new storages will be updated and a decision tree and rapid appraisal methodology for pre-feasibility will be developed that includes social and environmental costs.
- A pro-active risk management approach will be developed. Water resource planning techniques will increase in sophistication and the community will be made more aware of risk management and its implications.
References
Water Resources Division, Power and Water Authority - NT Water Blueprint for Future Direction.
Gordon, N. D., McMahon, T. A. and Finlayson, B. L. (1992). Stream Hydrology - An Introduction for Ecologists, John Wiley & Sons, Chichester.
Jolly, P. B. and Chin, D. N. (1991). Long term rainfall - recharge relationships within the Northern Territory, Australia. The Foundations of Sustainable Development. Proceedings of the International Hydrology and Water Resource Symposium ÒChallenges for Sustainable DevelopmentÓ, Perth 2 - 4 October, 824 - 829.
The Australian Urban Water Industry Report 1999.
Tickell, S. J. (1994). Dryland Salinity Hazard Map of the Northern Territory. Report 54/94D, Northern Territory Power and Water Authority, Darwin.
AWRC - Australian Water Resources Council. (1987). 1985 Review of Australian Water Resources and Water Use. Vol. 1 & Vol. 2, November 1987.
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