FLOOD WARNING SYSTEM
for the
NEBINE, MUNGALLALA AND WALLAM CREEKS

Wallam Creek at Homeboin

Contained in this document is information about: (Last updated June 2008) Flood Risk Previous Flooding Flood Forecasting Local Information Flood Warnings and Bulletins Interpreting Flood Warnings and River Height Bulletins Flood Classifications Catchment Map

Flood Risk

The Nebine, Mungallala and Wallam Creek catchments are located about 100 to 150 kilometres west of St George in southwestern Queensland and drain an area of approximately 36,000 square kilometres. Mungallala Creek rises in the Chesterton Ranges 50 kilometres northwest of Mitchell. The Nebine and Wallam Creeks rise in an area south of a line between Mitchell and Morven. The small townships of Bollon and Mungallala are the only towns in the catchment.

All three creek systems flow in a southerly direction, parallel to each other for some 250 to 300 kilometres, before crossing the Queensland and New South Wales border west of the town of Hebel. They join the Culgoa River prior to entering the Darling River system upstream of Bourke. 

Floods normally develop in the headwaters area of Nebine, Mungallala and Wallam Creeks. However, general heavy rainfall situations may occur throughout these vast catchments. In recent years, the catchments have seen extensive flooding particularly in May 1983, April 1990 and February 1997.

Previous Flooding

Previous flood information for the Nebine, Mungallala and Wallam Creek catchments are well documented, with river height records for Homeboin and Tomoo dating back to the 1950's.

Flood Forecasting

The Bureau of Meteorology operates a flood warning system for the Nebine, Mungallala and Wallam Creeks based on a rainfall and river height observations network shown on the map. The network consists of a number of volunteer rainfall and river height observers who forward observations by telephone when the initial flood height has been exceeded at their station. 

The Bureau's Flood Warning Centre issues Flood Warnings and River Height Bulletins for the Nebine, Mungallala and Wallam Creeks during flood events. Qualitative flood forecasts are issued when moderate flood levels are likely to be exceeded. 

Local Information

The Local Government is able to provide further information on flooding in your area of the Nebine, Mungallala and Wallam Creek catchments.

Flood Warnings and Bulletins

The Bureau of Meteorology issues Flood Warnings and River Height Bulletins for the Nebine, Mungallala and Wallam Creek catchments regularly during floods. They are sent to radio stations for broadcast, and to local Councils, emergency services and a large number of other agencies involved in managing flood response activities. Flood Warnings and River Height Bulletins are available via : 

Local response organisations

Internet/World Wide Web

Telephone Weather

Interpreting Flood Warnings and River Height Bulletins

Flood Warnings and River Height Bulletins contain observed river heights for a selection of the river height monitoring locations. The time at which the river reading has been taken is given together with its tendency (e.g. rising, falling, steady or at its peak). The Flood Warnings may also contain predictions in the form of minor, moderate or major flooding for a period in the future. River Height Bulletins also give the height above or below the road bridge or causeway for each river station located near a road crossing. 

One of the simplest ways of understanding what the actual or predicted river height means is to compare the height given in the Warning or Bulletin with the height of previous floods at that location. 

The table below summarises the flood history of the Nebine, Mungallala and Wallam Creek catchments - it contains the flood gauge heights of the more significant recent floods.

Historical flood heights for all river stations in the Nebine, Mungallala and Wallam Creek catchments Floodwarning network, as shown on the map, are available from the Bureau of Meteorology upon request.

Flood Classifications

At each flood warning river height station, the severity of flooding is described as minor, moderate or major according to the effects caused in the local area or in nearby downstream areas. Terms used in Flood Warnings are based on the following definitions.

Major Flooding : This causes inundation of large areas, isolating towns and cities. Major disruptions occur to road and rail links. Evacuation of many houses and business premises may be required. In rural areas widespread flooding of farmland is likely. Moderate Flooding : This causes the inundation of low lying areas requiring the removal of stock and/or the evacuation of some houses. Main traffic bridges may be closed by floodwaters.  Minor Flooding : This causes inconvenience such as closing of minor roads and the submergence of low level bridges and makes the removal of pumps located adjacent to the river necessary.

Each river height station has a pre-determined flood classification which details heights on gauges at which minor, moderate and major flooding commences. Other flood heights may also be defined which indicate at what height the local road crossing or town becomes affected by floodwaters. 

The table below shows the flood classifications for selected river height stations in the Nebine, Mungallala and Wallam Creek catchments.  

All heights are in metres on flood gauges.

(B) = Bridge  (A) = Approaches  (C) = Causeway  (X) = Crossing

The above details are correct at the time of preparing this document. Up-to-date flood classifications and other details for all flood warning stations in the network are at:

http://www.bom.gov.au/hydro/flood/qld/networks/index.shtml

Catchment Map showing the Nebine, Mungallala & Wallam Creek flood warning network

For further information, contact:
The Regional Director, Bureau of Meteorology, GPO Box 413, Brisbane Q 4001