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National Water Account 2016

Ord: Geographic information

The Ord River is one of the more significant waterways in northern Australia. A distinctive feature is Lake Argyle, a Ramsar-listed wetland of international importance, which supports irrigated agriculture and hydroelectric generation in the region. Groundwater is also an important water source in the region, primarily used for mining purposes and town supply.

General description

Area: 65,800 km²
Population: 9,000 (Australian Bureau of Statistics [ABS] 2011)

The Ord region is located in the East Kimberley region of Australia, as shown in Figure R1. The region overlaps the border between Western Australia and the Northern Territory. About 75% of the region is in Western Australia.

 

Figure R1  Location map of the Ord region within Australia
Figure R1 Location of the Ord region within Australia

 

The boundary of the Ord region is physically defined by two surface water catchments: the Ord River and the Keep River (Figure R2).

 

Figure R2  Contextual map of the Ord region
Figure R2 Contextual map of the Ord region

 

The Ord River catchment is one of the major river systems in northern Australia and forms the greater part of the Ord region. It extends from the Kimberley Plateau in the south and discharges into the Cambridge Gulf near Wyndham, via the Ord River estuary. The Ord River catchment includes the King River (Figure R2) which supplies water to the town of Wyndham.

The Keep River catchment, which lies in the northeast of the Ord region, extends from the Pinkerton Range in the southeast and discharges into the Timor Sea.

 

Region definition

The Ord region is physically defined by the boundaries of the Ord River and Keep River catchments and includes all water resources within or beneath the physical area.

The region includes water stored in and transactions related to:

Lake Argyle, Ord River iStock © author unknown

  • surface water storages in the region
  • rivers within the region
  • groundwater aquifers beneath the region.

The Ord region excludes water stored in and transactions related to:

  • water held in pipes and infrastructure of the urban water system
  • off-channel water storages and rainwater tanks, such as farm dams and private commercial water storages used to harvest runoff or collect rainwater
  • water held in the landscape, such as soil moisture.

For more information regarding items in this water accounting report, please refer to the Water accounting policies note.

 

Land use

The Ord region contains several small urban centres, remote stations, and Aboriginal settlements. The largest urban centres in the region are:

  • Kununurra: urban centre population 4,600
  • Halls Creek: urban centre population 1,400
  • Wyndham: urban locality population 800 (ABS 2011).

Other settlements in the region include Warmun, Durack, and Lake Argyle Village. Urban areas make up less than 0.1% of the region.

The major land uses in the Ord region include:

  • pastoral grazing
  • conservation and natural environments.

These two land use categories make up approximately 79% and 19% of the region respectively. The relative area and location of each major land use in the Ord region is shown in Figure R3 (Australian Bureau of Agricultural and Resource Economics and Sciences 2014).

 

Figure R3  Map of land use in the Ord region
Figure R3 Land use in the Ord region

 

Most irrigated agriculture occurs in the Ord River Irrigation Area and land adjacent to the Ord River that has access to water for irrigation. All of this irrigated land is downstream of Lake Argyle and makes up approximately 0.2% of the region. A variety of crops are grown in these areas, with the major crops being sandalwood, mahogany, and a range of horticultural crops and grains.

Key mining activities in the region concern diamonds and nickel. Argyle Diamond Mine is situated near Lake Argyle and uses water from Lake Argyle for its operations. Nickel is also mined approximately 120 km north of Halls Creek. The total mining area makes up less than 0.1% of the region.

There are over 4,000 km² of parks and reserves in the Ord region, including:

These areas, which are shown in Figure R2 and identified as 'Conservation and natural environments' in Figure R3, are of cultural significance and form the basis of the tourism industry in the region.

 

Significant aquatic ecosystems

The region contains several significant aquatic ecosystems (as shown in Figure R4):

 

Figure R4  Map of significant wetlands in the Ord region
Figure R4 Significant wetlands in the Ord region

 

The Ord River and associated aquatic ecosystems have a strong cultural significance for a number of Aboriginal groups, particularly the Miriuwung and Gajerrong peoples (Barber and Rumley 2003).

 

Water resources

There are five major surface water resources in the Ord region:

Champagne Springs, Western Australia (iStock © Sam Valtenbergs)

  • Lake Argyle
  • Lake Kununurra
  • Arthur Creek storage
  • Ord River channel
  • Moochalabra storage.

There are two groundwater resources in the Ord region:

  • Kununurra aquifers
  • Halls Creek aquifers.

Tributaries of the Ord River, both upstream and downstream of Lake Argyle, provide additional water resources.

Surface water resources support the main water users in the region, including irrigated agriculture, hydroelectric power generation, commercial forestry, and urban and self-supply licensees.

Groundwater resources in the region are primarily used for mine dewatering and operations and also urban supply.

 

Surface water

Surface water resources of the Ord region are highly developed due to the Ord River Irrigation Scheme. Lake Argyle, one of Australia's largest human-made storages, is used to supply water to irrigated agriculture and forestry. Other storages and tributaries are used to supply townships and self-supply irrigators.

 

Storages

Major storages within the Ord region are shown in Figure R5.

 

Figure R5  Map of major storages in the Ord region; capacity of each storage is also shown
Figure R5 Major storages in the Ord region; capacity of each storage is also shown

 

Lake Argyle is formed by the Ord River Dam, and collects runoff from the upper Ord River catchment. Water is released from Lake Argyle for hydroelectric power generation, and the resulting flows are used to supply downstream users and meet environmental water provisions in the lower Ord River.

Most of the inflow into Lake Kununurra, which is formed by the Kununurra Diversion Dam, comes from water released from Lake Argyle. Runoff from the catchment between Lake Argyle and the Kununurra Diversion Dam (approximately 1,000 km²) also contributes inflows into the lake during the wet season. Lake Kununurra is primarily used to supply water to the Ord River Irrigation Area (see Irrigation scheme).

Arthur Creek is a large private storage located on a tributary of the Dunham River that is used for self-supply irrigation. Moochalabra, located on the King River in the western part of the Ord region, is used for Wyndham's town water supply.

 

Rivers

Seasonal flow characteristics of rivers within the Ord region reflect the annual rainfall pattern of the region. Most of the rainfall occurs during the wet season (November–March). Consequently, most of the streamflow within the region occurs between January and May (Figure R6).

The gauging stations used to represent the general seasonal flow patterns of the Ord region in Figure R6 are located along the Negri River at the Mistake Creek Homestead (Station 809315), and along the Ord River at the Old Ord Homestead (Station 809316) and at Tarrara Bar (Station 809339). These three stations are shown in Figure R7. There are other gauging stations in the Ord region although they are not shown in this map.

Upstream of Lake Argyle, flows are very low or cease to flow during the dry season (April–October). The Ord River below Lake Argyle receives specific releases to maintain minimum environmental flows in the lower Ord River. Consequently, flow in the lower Ord River is perennial (Figure R6).

Other rivers in the Ord region, such as the Dunham, Keep and King rivers, also exhibit seasonal flow patterns similar to rivers upstream of Lake Argyle.

 

Figure R6  Graph of mean monthly flows along the Ord (upper and lower) and Negri rivers and mean monthly rainfall for the Ord region
Figure R6 Mean monthly flows along the Ord (upper and lower) and Negri rivers and mean monthly rainfall for the Ord region

 

Figure R7  Map of key flow gauging stations along the main rivers within the Ord region
Figure R7 Key flow gauging stations along the main rivers within the Ord region

 

Licensed river access

Self-supply licensees access water from rivers for commercial mining and forestry operations, small scale irrigation, and stock and domestic purposes. Licensed river access represents less than 10% of the total surface water entitlements in the Ord region.

Private irrigation development at Arthur Creek on the Dunham River is the largest entitlement in the region outside of the Ord River Irrigation Area, with approximately 20,000 ML per annum licensed for diversion.

The Keep River is not currently accessed as a water resource. The Western Australian Government plans to develop the resource as part of the Ord–East Kimberley Expansion Project (see Major water reforms in 'Climate and Water' for more information).

The Ord River, downstream of Lake Argyle, is regulated by releases of water from Lake Argyle to maintain flows in the lower Ord River. Self-supply licensees access the river for small scale irrigation, industrial, commercial, and stock and domestic purposes.

 

Groundwater

Groundwater resources in the region are not extensively developed. Borefields in localised fractured rock aquifers are used for urban supply to Halls Creek and mining operations in the upper reaches of the Ord region. Sedimentary aquifers adjacent to Lake Kununurra are used to supply the town of Kununurra.

Groundwater monitoring occurs in sedimentary aquifers underlying the Ord River Irrigation Area. Although no groundwater is used for irrigation, the focus of the groundwater monitoring is the rising water table caused by irrigation activities.

An expansion of the monitoring bore network and improved understanding of aquifer extent, properties, and groundwater processes would be required if groundwater resources in the region were to be developed.

 

Water systems

Irrigation scheme

The Ord River Irrigation Area comprises an open canal network that is used to distribute water for irrigated agriculture. About 130 km² is irrigated on the Ivanhoe Plain (to the east and north of the river), with 20 km² irrigated on the Packsaddle Plain (to the west of the river), as shown in Figure R8. Irrigation has also now commenced on the 74 km² of land in the Goomig Farmlands (see Major water reforms).

Water supplied to the Ord River Irrigation Area represents more than 90% of the total surface water entitlements in the Ord region. Irrigation water is diverted from the Ord River at Lake Kununurra to the Ivanhoe and Packsaddle plains via the M1 supply channel and the Packsaddle pump station respectively. Irrigation water to the Goomig Farmlands is also currently diverted at Lake Kununurra via the M1 supply channel.

Most of the irrigation water is diverted via the M1 supply channel to the Ivanhoe Plain and Goomig farmlands; less than 10% is diverted to the Packsaddle Plain (Department of Water 2013).

 

Figure R8  Map of Ord River Irrigation Area
Figure R8 Ord River Irrigation Area

 

Areas of proposed irrigation expansion within the Ord region are described in Major water reforms in 'Climate and water'.