1.1.5.1 Surface water systems


This section describes the rainfall, evaporation, river systems, flooding history and water storage infrastructure in each river basin of the Clarence-Moreton bioregion. Table 9 details the area, percentage agricultural land, rainfall, evaporation and runoff for each river basin as reported for the National Land and Water Resources Audit (NLWRA, 2001). River basin sizes in the bioregion range from 508 km2 for the Brunswick River to over 22,000 km2 for the Clarence River. Rainfall ranges from an annual mean of 922 mm for the Brisbane river basin to 1879 mm for the Brunswick river basin. Mean annual actual evaporation ranges between 800 to 1131 mm and runoff coefficients (runoff divided by rainfall) vary by a factor of more than two (0.14–0.40) across the bioregion (NLWRA, 2001). The water supply infrastructure in each river basin is described in more detail in the following sections, but it is also worth noting the existence of the SEQ water grid (Queensland Water Commission, 2010) which connects many of the river basins and population centres in south-east Queensland. The SEQ water grid connects the water supply system provided by 12 dams in the region – from the Gold Coast in the south to the Sunshine Coast in the north and Toowoomba in the west. A total of 535 km of pipeline connects the dams and water supply systems so that water can be moved throughout the region to meet demands. The grid is also connected to the Western Corridor Recycled Water Project and the Gold Coast desalination plant.

Table 9 River basin characteristics and annual rainfall, actual evaporation (canopy + soil) and runoff


Basin

Brisbane River

Logan-Albert River

South Coast

Tweed River

Brunswick River

Richmond River

Clarence River

Area (km2)

13,572

4141

1349

1077

508

7020

22,284

Agricultural land proportion (%)

16%

15%

27%

23%

31%

10%

5%

Rainfall (mm/y)

922

1055

1551

1846

1879

1334

1111

Actual evaporation (mm/y)

800

862

1043

1105

1131

947

854

Runoff (mm/y)

129

199

509

742

752

390

257

Runoff (GL/y)

1751

824

687

799

382

2737

5726

Runoff coefficient (runoff/rainfall)

0.14

0.19

0.33

0.40

0.40

0.29

0.23

Source data: NLWRA (2001)

1.1.5.1.1 Brisbane river basin

The Brisbane river basin (Figure 22) is the most northerly in the Clarence-Moreton bioregion and covers an area of 13,572 km2. The description presented here is relevant to the entire Brisbane river basin; however, it should be noted that only 42% of this river basin (mainly in the south) is included within the bioregion boundary. The headwaters are located on the eastern side of the Great Dividing Range with the river draining to the coast into Moreton Bay downstream of Brisbane. A number of tributaries contribute to the Brisbane River including the Bremer and Stanley rivers, and the Cooyar, Emu, Cressbrook, Lockyer, Laidley, Buaraba and Warrill creeks. A water resource management plan has been established for the Brisbane river basin to control the allocation and sustainable use of water. Details are provided in the Queensland Government’s Water Resource (Moreton) Plan 2007 and those interested in further information are directed to this piece of legislation. The Water Resources Plan defines the availability of water, sustainable extractions of surface water, groundwater and overland flow, and priorities for future water requirements.

The major water supply storages include Wivenhoe Dam (capacity 1165 GL) and Somerset Dam (capacity 380 GL), which combined account for approximately 70% of the water storage capacity for the city of Brisbane. These dams are part of the SEQ Water Grid, which links water storages and allows water transport through this region. Wivenhoe and Somerset dams also have an additional flood storage capacity of 1974 GL. Other significant storages in the Brisbane river basin include Moogerah Dam (capacity 84 GL) on Warrill Creek and Atkinson (capacity 30 GL) and Clarendon (capacity 24 GL) dams in the Lockyer Valley.

The major areas of irrigated agriculture are located within the Central Lockyer Valley, Lower Lockyer and Warrill Valley water supply schemes. Other smaller areas of irrigation are fed by a number of small water storages and groundwater bores. Of the total area of the Brisbane river basin, 4% is used for irrigated agriculture (CLUM, 2012).

Mean annual rainfall for the basin is 922 mm and mean annual actual evaporation is 800 mm (Table 9). The river flows year round and modelled mean annual flow for the entire basin is 1751 GL (NLWRA, 2001). The runoff coefficient (runoff/rain) is 0.14 making it the lowest of any of the basins in the bioregion (NLWRA, 2001). In part, this relatively low runoff coefficient is a consequence of the basin’s relatively low rainfall, but is also partly due to the substantial level of flow regulation in the basin.

The Brisbane river basin is occasionally subjected to cyclonic activity and associated monsoon depressions which can bring extremely high rainfall and, therefore, flooding to this region. There have been 11 major floods in the Brisbane River at the city since 1830 with the most recent occurring in 2011, which resulted in widespread inundation of much of the low-lying areas of the basin. The occurrence of floods in the Brisbane River at the city has been greatly reduced since the construction of the Wivenhoe Dam in 1984. The mean annual flow at Savages Crossing gauge, which is located on the Brisbane River downstream of Wivenhoe Dam and 131 km from the river mouth, is 755 GL for the period between 1961 and 2012. The upstream catchment area at this point is equivalent to 75% of the total area of the Brisbane river basin. The maximum daily flow recorded during this period is 641 GL.

Figure 22

Figure 22 Brisbane river basin, major water storages and active stream gauging locations

1.1.5.1.2 Logan-Albert river basin

The Logan-Albert river basin (Figure 23) covers an area of 4141 km2. Its headwaters are located in the Border Ranges which include parts of the Mount Barney and Lamington national parks. This basin has two main rivers: the Logan River, which accounts for about 80% of the total basin area; and the Albert River, which contributes the remaining 20%. Most of the Logan river basin (85%) is located within the bioregion boundary. The excluded area covers a large component of the coastal lowlands. The two rivers join and flow into the lagoons and tidal wetlands of southern Moreton Bay. The tributaries of the Logan River include Teviot Brook and Christmas and Running creeks. Major water storages in the Logan river basin include Maroon Dam (capacity 44 GL) and Wyaralong Dam (capacity 103 GL). A water resource management plan has been established for the Logan-Albert river basin to control the allocation and sustainable use of water. Details are provided in the Queensland Government’s Water Resource (Logan Basin) Plan 2007 and those interested in further information are directed to this piece of legislation. The Water Resources Plan defines the availability of water, sustainable extractions of surface water, groundwater and overland flow, and priorities for future water requirements.

About 16% of the Logan-Albert river basin is under agricultural production, but just 3% of the total area is accounted for by irrigated agriculture (CLUM, 2012). While irrigation occurs across a number of areas of the Logan-Albert river basin, the Logan River Water Supply Scheme is the largest and includes an irrigation area along a 101 km stretch of the Logan River and along a 27 km stretch of Burnett Creek (Seqwater, 2012). This scheme includes the Maroon and Wyaralong dams, the Cedar Grove, Bromelton and South Maclean weirs and an off-stream storage at Bromelton.

Mean annual rainfall for the basin is 1055 mm and mean annual actual evaporation is 862 mm (Table 9). The river flows year round and modelled mean annual flow for the entire basin is 824 GL with a runoff coefficient of 0.19 (NLWRA, 2001). According to the Bureau of Meteorology’s flood warning alerts, average basin rainfall in excess of 200 mm in 24 hours may result in moderate flooding while average basin rainfall in excess of 300 mm in 24 hours may result in severe flooding. The most notable flood was that of January 1974, in which major flooding occurred throughout south-east Queensland. The streamflow gauge on the Logan River at Yarrahappini has a catchment area equivalent to 58% of the total area of the Logan-Albert river basin and is located 78 km from the river mouth. Its mean annual flow was 310 GL for the period between 1970 and 2012. The maximum daily flow recorded during this period was 368 GL (i.e. greater than the mean annual flow).

Figure 23

Figure 23 Logan-Albert river basin, major water storages and active stream gauging locations

1.1.5.1.3 South Coast basin

The total area of the South Coast basin is 1349 km2 (Figure 24). This basin includes the Coomera River and the Nerang River, both of which flow into the Broadwater and then to the Coral Sea. Mudgeeraba Creek flows into the Nerang River while the three remaining major creeks – Reedy, Tallebudgera and Currumbin – flow directly to the Coral Sea. Only 10% of the South Coast basin falls within the Clarence-Moreton bioregion, with the intersecting area forming the south-western headwaters of the basin.

A water resource management plan has been established for the South Coast basin to control the allocation and sustainable use of water. Details are provided in the Queensland Government’s Water Resource (Gold Coast) Plan 2007 and those interested in further information are directed to this piece of legislation. The Water Resources Plan defines the availability of water, sustainable extractions of surface water, groundwater and overland flow, and priorities for future water requirements.

The major water storages in the South Coast basin include Hinze Dam and Little Nerang Dam. Hinze Dam is the largest with a capacity of 311 GL and it provides most of the water for the Gold Coast and some flood mitigation. This dam has been built in a number of stages with the latest being completed in 2011. Little Nerang Dam (7 GL capacity) is a secondary source of water for the Gold Coast. Some irrigated agriculture is found in this basin (0.1% of total area) but it is not widespread (CLUM, 2012).

Mean annual rainfall for the basin is 1551 mm and mean annual actual evaporation is 1043 mm (Table 9). The rivers flow year round and modelled mean annual flow for the entire basin is 687 GL with a runoff coefficient of 0.33 (NLWRA, 2001). Most flooding in this basin is associated with cyclonic activity. Since records commenced in 1920, there have been four major flooding events. The mean annual flow for the Nerang River at Glenhurst (146002B), which is the furthest point downstream on the largest river system in this basin, was 88 GL for the period between 1970 and 2012. The maximum daily flow recorded during this period was 100 GL.

Figure 24

Figure 24 South Coast basin, major water storages and active stream gauging locations

1.1.5.1.4 Tweed river basin

The Tweed river basin (Figure 25) covers an area of 1077 km2. Only 39% of the basin falls within the Clarence-Moreton bioregion and most of this represents headwater areas. The basin is formed in the caldera of the now extinct Tweed Volcano of which Mount Warning is the volcanic plug. Major tributaries to the Tweed River include the Rous and Oxley rivers and numerous smaller creeks. The Tweed River flows to the Coral Sea at Tweed Heads. Cobaki Broadwater, Terranora Broadwater and Cudgen Lake are large natural near-coastal water bodies in this basin.

A water resource management plan has been established for the Tweed river basin to control the allocation and sustainable use of water. Details are provided in the NSW Government’s Water Sharing Plan for the Tweed River Area Unregulated and Alluvial Water Sources 2010 and those interested in further information are directed to this piece of legislation. The Plan defines the availability of water, sustainable extractions, storage operation rules, and management of water access licences.

Most of the water use in this basin is for town supply, however, it is also used for irrigation of pasture for dairying and horticulture. Irrigation accounts for less than 1% of the total area (CLUM, 2012). The Clarrie Hall Dam (capacity 15 GL) is the only dam in the Tweed river basin and is used to supplement the water supply for the Tweed Shire. Weirs exist on the Oxley River at Tyalgum and at Bray Park on the Tweed River.

Mean annual rainfall for the basin is 1846 mm and mean annual actual evaporation is 1105 mm (Table 9). The river flows year round and modelled mean annual flow for the entire basin is 799 GL. Its runoff coefficient of 0.40 is the highest in the bioregion (NLWRA, 2001). As with other basins in this region, flooding is associated with cyclonic activity. The last major flood in the area occurred as a result of the passing of ex-tropical cyclone Oswald in 2013. The mean annual flow at Uki (201900) on the Tweed River, which has an upstream catchment area of 275 km2, was 142 GL for the high quality data period between 1968 and 2012. The maximum daily flow recorded during this period was 54 GL.

Figure 25

Figure 25 Tweed river basin, major water storages and active stream gauging locations

1.1.5.1.5 Brunswick river basin

The Brunswick river basin (Figure 26) is the smallest in the Clarence-Moreton bioregion and covers an area of 508 km2. Only 11% of the Brunswick river basin is contained within the Clarence-Moreton bioregion, comprising the headwaters at the southern end of the basin. A water resource management plan has been established for the Brunswick river basin to control the allocation and sustainable use of water. Details are provided in the NSW Government’s Water Sharing Plan for the Upper Brunswick River Water Source 2003 and those interested in further information are directed to this piece of legislation. The Plan defines the availability of water, sustainable extractions, storage operation rules, and management of water access licences.

A weir is located on Mullumbimby Creek upstream of the Mullumbimby township and further upstream is the Mullumbimby hydro-power station. The water supply for Mullumbimby comes from the Laverty’s Gap weir which is on the Wilsons River in the neighbouring Richmond river basin. Most of the major creeks and rivers in the Brunswick river basin flow to the sea through a large estuary which then drains to the ocean through Brunswick Heads. Lacks Creek and Marshalls Creek in the north, and Tyagarah and Simpsons Creek in the south join the Brunswick River at its estuary. Mullumbimby Creek, Yankee Creek and Pipeclay Creek join the Brunswick River upstream. Belongil Creek forms a small estuary behind the beach north of Byron Bay.

More than 30% of the basin is under agricultural production (NLWRA, 2001), while irrigated agriculture accounts for a little over 1% of the total area (CLUM, 2012). Water is used to irrigate pasture for dairying, turf farming and horticulture.

Mean annual rainfall for the basin is 1879 mm, which is the highest amongst all basins of the Clarence-Moreton bioregion. Mean annual actual evaporation is 1131 mm, which is also the highest in the bioregion (Table 9). The rivers flow year round and modelled mean annual flow for the entire basin is 382 GL with a runoff coefficient of 0.40 (NLWRA, 2001). Major floods have occurred in this basin in 1974, 1976, 1978 and 2005 with extensive inundation of low-lying areas. The mean annual flow on the Brunswick River at Durrumbul, which has an upstream catchment area of 34 km2, was 31 GL between 1955 and 2012. The maximum daily flow recorded during this period was 11 GL.

Figure 26

Figure 26 Brunswick river basin, major water storages and active stream gauging locations

1.1.5.1.6 Richmond river basin

The Richmond river basin (Figure 27) covers an area of 7020 km2. The vast majority (95%) of this basin falls within the Clarence-Moreton bioregion. Its headwaters are located in the Border Ranges, Tweed Volcano and the Richmond Range. The major tributaries to the Richmond River include Wilsons River, Coopers Creek, Terania Creek, Leycester Creek, Iron Pot Creek, Shannon Brook, Sandy Creek and Bungawalbin Creek. The Richmond River has a large barrier estuary which flows to the ocean at Ballina. The Evans River forms in a small sub-basin to the south which flows to the coast at Evans Head. This river is joined to the Richmond River by a canal that was constructed to alleviate flooding.

A water resource management plan has been established for the Richmond river basin to control the allocation and sustainable use of water. Details are provided in the NSW Government’s Water Sharing Plan for the Richmond River Area Unregulated, Regulated and Alluvial Water Sources 2010 and those interested in further information are directed to this piece of legislation. The Plan defines the availability of water, sustainable extractions, storage operation rules, and management of water access licences.

Water storages in the basin include Toonumbar Dam (capacity 11 GL),which stores water for irrigation stock and town water; and Rocky Creek Dam (capacity 14 GL) and Emigrant Creek Dam (capacity 0.82 GL), which provide water for the towns of Lismore and Ballina. There are three weirs on the Richmond River near Casino and one on the Wilsons River that provides water to Mullumbimby in the Brunswick river basin. Approximately 1% of the Richmond river basin is used for irrigated agriculture (CLUM, 2012). Irrigated pastures are found around the alluvial flats of the Richmond and Wilson rivers and groundwater is used to irrigate fruit and nut crops on the Alstonville Plateau.

Mean annual rainfall for the basin is 1334 mm and mean annual actual evaporation is 947 mm (Table 9). The rivers flow year round and modelled mean annual flow for the entire basin is 2738 GL with a runoff coefficient of 0.29 (NLWRA, 2001). Many major floods have been documented for the Richmond River and the towns of Ballina, Casino and Lismore. As with other basins in the Clarence-Moreton bioregion, these floods are normally associated with extreme rainfall derived from cyclonic activity. The mean annual flow on the Richmond River at Casino (203004), which has an upstream catchment area of 1790 km2, was 587 GL for the high quality data period between 1944 and 2012. The maximum daily flow recorded during this period was 154 GL.

Figure 27

Figure 27 Richmond river basin, major water storages and active stream gauging locations

1.1.5.1.7 Clarence river basin

The Clarence river basin (Figure 28) has the largest area and discharge of all NSW coastal river basins. The total area is 22,284 km2. Of the total area, 35% – mainly in the lower parts of the basin – falls within the Clarence-Moreton bioregion boundary. The headwaters are located in the Macpherson Ranges in the north; the Baldblair Ranges, Doughboy Ranges and the Dorrigo Plateau in the south; and the Great Dividing Range in the west. The major tributaries to the Clarence River include the Maryland, Cataract, Timbarra, Mann, Guy Fawkes, Nymboida and Orara rivers. Before entering the Coral Sea at Yamba, the river passes through a large estuary system which includes Wooloweyah Lagoon and The Broadwater.

A water resource management plan has been established for parts of the Clarence river basin to control the allocation and sustainable use of water. Details are provided in the NSW Government’s Water Sharing Plan for the Dorrigo Plateau Surface Water Source and Dorrigo Basalt Groundwater Source 2003 and those interested in further information are directed to this piece of legislation. The Plan defines the availability of water, sustainable extractions, storage operation rules, and management of water access licences. A merger of this Plan with a proposed plan for Clarence River unregulated and Alluvial water sources is likely in the future.

Most of the Clarence river basin is unregulated. Major water storages in this basin are associated with the Nymboida River and include Shannon Creek Dam (capacity 30 GL), Karangi Dam (capacity 6 GL) and Rushford Road Reservoir (100 ML). A weir on the Nymboida River supplies water to the Karangi Dam. Non-irrigated agriculture dominates the Clarence Valley with only small areas of irrigation. An Australian Bureau of Statistics analysis (ABS, 2006) estimated that 0.3% of the total agricultural land in the Clarence valley was irrigated.

The mean annual rainfall for the basin is 1111 mm and mean annual actual evaporation is 854 mm (Table 9). The river flows year round and modelled mean annual flow for the entire basin is 5727 GL – the largest in the bioregion. The runoff coefficient is 0.23 (NLWRA, 2001). The headwaters for the Clarence river basin represent some of the highest rainfall areas in NSW. As a result, flooding is a regular occurrence. There have been 73 major and moderate flood events since 1839 (based on the Grafton streamflow gauge). Extensive levee walls have been constructed to protect Grafton and Maclean from flooding. The mean annual discharge between 1923 and 2012 of the Clarence River at Lilydale gauge (204007), which has an upstream catchment of 16,690 km2, was 3400 GL. The maximum daily flow recorded during this period was 1200 GL.

Figure 28

Figure 28 Clarence river basin, major water storages and active stream gauging locations

Last updated:
23 March 2016
Thumbnail images of the Clarence-Moreton bioregion

Product Finalisation date

28 May 2014