Dry Tropics Catchments
The Dry Tropics Catchments, located in north eastern Queensland, covers and area of approximately 133,242km2 (equivalent to about 8% of the state) and has a population of approximately 190,000. The region is comprised of several sub-catchments and spans three main bioregions. The vaious physical environments lead to an incredibly biodiverse region (Tait 2004).
The Dry Tropics Catchments are primarly defined by the catchment area of the Burdekin River plus the associated coastal and marine areas.
The region has a population of approximately 190,000 which is predominately urban with up to three quarters based within major population centres including the twin cities of Townsville-Thuringowa, Ayr, Bowen and Charters Towers. Away from the major centres the region is very sparsely populated. The population is increasing in the larger centres of Thuringowa and Townsville, however most rural areas are experiencing population decline.
Approximately 5% of the population in the region is Indigenous. It includes the largest Torres Strait Islanders population outside of the Torres Strait, located primarily in the Townsville-Thuringowa area. There is also a significant Melanesian South Sea Islander population within the region particularly in the lower Burdekin which originates from indentured Kanaka labourers who were used in the development of the sugar industry in the late 1800s.
The economy of the Burdekin Dry Tropics region is heavily reliant upon natural resource based industries, particularly agriculture. Agriculture is by far the most important employer in the rural areas of the region. Other major industries include mining and tourism.
Following a period of European exploration in the mid 1800s, pastoralism spread through the Burdekin Dry Tropics region, gold was discovered in the Charters Towers and Ravenswood area. This consolidated the development of Townsville as a port of servicing mining centres and the development of the sugar industry which began on the floodplains of the Burdekin Delta.
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Hydrology
The Burdekin River Basin forms parto of Australia's North East Coast Drainage Division. Within this division it is bound by the Fitzroy River Basin to its southeast, by the Herbert River to the north and small catchments to the east. Its western margin adjoins two other drainage divisions, the Gulf of Carpentaria Drainage Division to the northwest and the internal Lake Eyre Drainage Division to the southwest. The Burdekin River is one of Australia's largest. It carries a massive sediment load and is on average the biggest single source of sediment and fresh water to the Great Barrier Reef lagoon.
The region is comprised of several distinct sub-catchments. These include two larger basins, the Upper Burdekin which drains the north west of the region including the western side of the coastal ranges, and the Belyando-Suttor which drains more arid inland areas in the south and the central west via the smaller Cape River. These two major basins flow to Lake Dalrymple formed by the Burdekin Falls Dam at the top of the Burdekin Gorge. Another significant catchment Burdekin sub-catchment, the Bowen-Broken, joins downstream from the Burdekin Gorge. From Clare downstream the drainage of localised rainfall and overbank flows is generally away from the main river via a number of prior river channels, which form floodplain and delta distributaries. These include the Barratta, Sheep Station, Plantation and Saltwater Creek systems.
River flows within the region reflect rainfall patterns, but are also affected by river regulation. Natural flows peak from December to April and are low to negligible from May to November. At this time many smaller tributaries cease flowing. In general, flows are dominated by large cyclone or monsoon driven events. These are pronounced annual flucuations and variable from year to year. High flows may be followd by extended dry periods. The catchments that drain the wetter coastal ranges i.e. the Upper Burdekin and the Bowen-Broken contribute more flow relative to their area than semi arid inland basins such as Belyando-Suttor.
| Sub-catchment | Area(km2) | %Area Burdekin Basin at Clare | Sub-catchment annual contribution (ML/a) | % of Total flow |
|---|---|---|---|---|
| Upper Burdekin | 36,181 | 28% | 4067000 | 52% |
| Belyando/Suttor | 73,828 | 57% | 2554500 | 33% |
| Bowen/Broken | 9,413 | 7% | 1021760 | 13% |
| Lower Burdekin | 10,028 | 8% | 132700 | 2% |
| Total at Clare | 129,450 | 100% | 7775960 | 100% |
On the Burdekin River flows below Lake Dalrymple are regulated by releases from the Burdekin Falls Dam. The Burdekin Falls Dam dominates flow regulation with an ability to store 1,860,000 ML of water which represents about 88% of the total constructed basin storage capacity (Roth et al. 2002).
Flows on the Bowen-Broken system are regulated by the Eungella Dam with some inter basin transfers out of the system to service nearby coal mining areas (NR&M 2000). Other smaller dams, weirs and river extractions also affect river flows in the region these include Paluma Dam, two weirs in the Upper Burdekin, the Collinsville Weir in the Bowen River, six weirs in the lower Burdekin and two on the Haughton (Roth et al. 2002).
The hydrology of the Lower Burdekin catchment is highly modified. Historically flows with the river and floodplain distributary systems were very seasonal but are now regulated. Some of the regulated flow is extracted from the river by several large pumping stations. These stations supply water to the Burdekin Haughton Water Supply Scheme(BHWSS) on the Burdekin and Haughton floodplains. This is undertaken via distributory streams and constructed channels and the North Burdekin Water boards aquifer replenishment schemes on the Burdekin Delta. Smaller sand dam and drop board structures that form part of these schemes and irrigation tail water flows, also affect the hydrology of receiving water bodies, including streams and wetlands.
Surface water flows and wetland hydrology within the region's coastal catchments including the Haughton and Ross Rivers are also modified by a range of dams, weirs, tidal barrages, constructed drainage networks, bund walls for ponded pasture and water extraction.
A major source on the Upper Ross River, the Ross River Reservoir provides the primary water supply for the cities of Townsville-Thuringowa. This reservoir has a pipeline connecting it to the Haughton Balancing Storage for emergency augmentation effectively drought proofing Townsville-Thuringowa. The pipeline is an important element in the future growth in this area.
Townsville and Thuringowa's other main piped water supply is sourced from Paluma Dam which is part of the Burdekin River catchment.
In most areas of the region rainfall is far less than the amount of water used by plants for transpiration, therefore in general terms there is not much water that passes through the soil to recharge groundwater acquifiers (Roth et al. 2002). However heavy monsoonal rainfall during the wet season will usually give some recharge. There is limited water balance and groundwater resources information available and tends to be for areas where shallow groundwater acquifiers are important for irrigation, industrial or residential water resources. These include the Don River and Burdekin River deltas and the lower Ross River and Black River catchments.
Assets
The region contains a number of assets:
- Land
- Biodiversity
- Water
- Coastal and Marine
- Atmosphere
- Community
- Cultural Resources
Threats
Each of these critical regional assets is affected by a number of threats. These threatening processes are broad and encompass a wide range of specific activities:
- Insufficient community engagement and capacity
- Lack of Traditional Owner involvement
- Excessive grazing pressure
- Water quality degradation
- Dryland Salinity/Irrigation Salinity
- Native vegetation degradation
- Loss of biodiversity
- Soil degradation
- Pests plants and animals
- Unsustainable development
- Poor data acquisition and monitoring
