1.1.5.3 Surface water flow


The surface water flow in the Gippsland Basin bioregion originates from four river regions (South Gippsland, Mitchell–Thomson, Snowy and East Gippsland) by its numerous headwater streams. Each of these river regions are characterised by large variations in discharge and flow duration. There are a large number of streamflow monitoring stations across the Gippsland Basin bioregion. A list of end-of-system stream gauges for major watercourses in the Gippsland Basin bioregion along with mean annual flow (MAF) and mean annual runoff (MAR) is given in Table 18. Details of the streamflow characteristics of different river regions that are included in the Gippsland Basin bioregion are described in the subsequent sections.

Table 18 List of stream gauges in the Gippsland Basin bioregion located in four river basins that are part of Gippsland Basin bioregion hydrological study


Gauge number

Name of stream gauge

River Region

Catchment area

(km2)

Mean annual flow

(GL)

Mean annual runoff (mm)

Data period

GS 221225

Bemm River upstream of pump house

East Gippsland

935

122

131

1966–1975 and 2009–present

GS 223209

Tambo River at Battens Landing

Mitchell–Thomson

2,781

206

74

1977–present

GS 223210

Nicholson River at Sarsfield

Mitchell–Thomson

471

41

87

1997–present

GS 224200

Mitchell River at Bairnsdale

Mitchell–Thomson

4,425

331

75

1889–present

GS 225201

Avon River at Stratford

Mitchell–Thomson

1,485

162

109

1976–present

GS 225232

Thomson River at Bundalaguah

Mitchell–Thomson

3,538

373

105

1976–present

GS 226227

Latrobe River at Kilmany South

Mitchell–Thomson

4,464

502

112

1976–present

GS 222200

Snowy River at Jarrahmond

Snowy River

13,420

912

68

1889–present

GS 227200

Tarra River at Yarram

South Gippsland

215

32

151

1946–present

GS 227201

Bruthen Creek at Woodside

South Gippsland

174

29

166

1946–1960

GS 227202

Tarwin River at Meeniyan

South Gippsland

1,067

254

238

1955–present

GS 227216

Albert River at Hiawatha (Below Falls)

South Gippsland

41

14

337

1964–1989

GS 227240

Merriman Creek at Prospect Road Seaspray

South Gippsland

529

28

52

1983–present

Source: Department of Environment and Primary Industries (2014b). Mean annual flow statistic sourced from Bureau of Meteorology (2014)

Water in the South Gippsland River Region is derived from several small river catchments within the bioregion. The average runoff varies from 52 mm for the Merriman Creek at Prospect Road Seaspray to 254 mm for the Tarwin River at Meeniyan. Although most streams in the South Gippsland River Region are perennial, streamflow varies between years and months. Figure 39 shows an example of yearly and monthly flow distribution based on observed streamflow at Meeniyan for the period of 1989 to 2013. MAF between the periods from 1989 to 2013 varies from 65 to 457 GL with a mean of 235 GL. Mean monthly flow varies from 2.5 to 51 GL with about 84% of the annual flow occurring from June to October.

Figure 39

Figure 39 Flow distribution at Meeniyan on the Tarwin River in South Gippsland River Region for the Gippsland Basin bioregion, (a) mean monthly and (b) annual (GS:227202)

Data: Bioregional Assessment Programme (Dataset 5)

Water in the Mitchell–Thomson River Region is predominantly derived from runoff from headwater catchments. The average runoff across the river region varies from 41 mm for the Nicholson River at Sarsfield to 502 mm for the Latrobe River at Kilmany South. Streamflow in Mitchell–Thomson River Regions varies between years from very small flow to large flooding, and between months. Figure 40 shows an example of yearly and monthly flow distribution based on gauge data for the period of 1980 to 2013 at Glenaladale on the Mitchell River. MAF at Glenaladale varies from 123 to 1394 GL with a mean of 724 GL. Mean monthly flow varies from 16 to 138 GL between the months with 78% of the annual flow occurring from June to October.

Figure 40

Figure 40 Flow distribution at Glenaladale on the Mitchell River in Mitchell-Thomson River Region for the Gippsland Basin bioregion, (a) mean monthly and (b) annual (GS:224203)

Data: Bioregional Assessment Programme (Dataset 5)

Water in the Snowy River Region is predominantly derived from runoff from the headwater catchments of the Snowy River, located outside the bioregion. The runoff across the river region varies based on location within the river region. The mean annual runoff for a headwater catchment at Bombala is 89 mm and it is 68 mm at a downstream gauge at Jarrahmond on the Snowy River. Streamflow varies between years and months. Figure 41 shows an example of yearly and monthly flow distribution based on observed streamflow data at Sardine Creek on the Brodribb River in the Snowy River Region. MAF between the periods from 1980 to 2013 varies from 27 to 308 GL with a mean of 98 GL. Monthly flow varies from 5 to 20 GL with about 67% flow occurs during June to October.

Figure 41

Figure 41 Flow distribution at Sardine Creek on the Brodribb River in Snowy River Region for the Gippsland Basin bioregion, (a) mean monthly and (b) annual (GS:222202)

Data: Bioregional Assessment Programme (Dataset 5)

The source of water in the East Gippsland River Region that is part of Gippsland Basin bioregion originates in the headwaters of the Bemm and Cann rivers. Only the Bemm and Cann rivers of the East Gippsland River Region contribute surface water to the Gippsland Basin bioregion. The annual average runoffs are 131 mm and 168 mm for the Bemm river basin at pump house (GS 221225) and the Cann river basin at Offtake (GS 221224), respectively. All across the river region, streamflow varies between years and months. A typical example of monthly and annual flow distribution is shown in Figure 42. MAF between the periods from 1980 to 2013 varies from 48 to 417 GL with a mean of 160 GL. Monthly flow varies from 6 to 27 GL, 75% of the mean annual flow occurred during June to October.

Figure 42

Figure 42 Flow distribution at Princes Highway on the Bemm River in East Gippsland River Region for the Gippsland Basin bioregion, (a) mean monthly and (b) annual (GS:221212)

Data: Bioregional Assessment Programme (Dataset 5)

Information on water availability and entitlements is available for all major watercourses in the Gippsland Basin bioregion. Table 19 shows the annual average volume of surface water availability for consumptive use and water that remains in each river region for the environment. It is based on long-term annual averages of about 50 years of data reported in Department of Environment and Primary Industries (2011). It is important to note that because these are annual average estimates, the volume of use or streamflow in any one year is unlikely to match the annual average. Actual use and streamflow will vary from year to year with climate variability and the historical take-up of entitlements. The estimates in the table reflect an upper limit that could be taken under the entitlements, rather than historical use.

Table 19 Surface water availability and usage for the river regions in the Gippsland Basin bioregion


River Region

Mean annual flow (GL/year)

Bulk entitlements

(GL/year)

Licensed diversion

(GL/year)

Catchment dam

(GL/year)

Unallocated water

(GL/year)

Environmental entitlement

(GL/year)

Environmental flows

(GL/year)

East Gippsland

714.0

0.6

0.6

1.6

16.0

0.0

695.2

Mitchell–Thomson

3131.5

563.9

51.7

44.2

26.1

18.1

2427.5

Snowy

2162.1

1142.0

3.1

2.0

0.0

46.6

968.4

South Gippsland

911.5

9.6

10.5

32.2

38.0

0.0

821.3

Source: Department of Environment and Primary Industries, Victorian Government.

Note: Bulk entitlement includes unban, industrial and irrigation usage

Last updated:
8 January 2018
Thumbnail of the Gippsland bioregion

Product Finalisation date

2015