| Locks, Weirs and River Regulation |  |
How many locks & weirs are there?
- 40 locks on the Darling/Barwon River between Wentworth and Walgett
- 26 locks on the River Murray between Blanchetown in SA and Torrumbarry,
downstream of Echuca
- 9 locks on the Murrumbidgee River between the Murray junction and Hay.
<...Back to Top...>
Where are they?
River Murray Weirs and Locks
1. Blanchetown
2. Waikerie
3. Overland Corner
4. Bookpurnong
5. Renmark
6. Murtho
7. Rufus River
8. Wangumma
9. Kulnine
10. Wentworth
11. Mildura
15. Euston
26. Torrumbarry
(Locks 12 to 14 and 16 to 25 were abandoned from the original plans to regulate the River)
<...Back to Top...>
What do they do? What is a lock? What is a weir?
The weirs and locks along the River Murray serve three main purposes; 1. they facilitate navigation,
2. assist the diversion of water for irrigation
3. and improve regulation.
The weirs and locks were originally constructed on the Murray in the 1920s and 1930 to provide year-round navigation for commercial cargo and passenger paddlesteamer. They are maintained and operated for the Murray-Darling Basin Commission by the NSW, Victorian and SA Constructing Authorities to serve an increasing number of houseboats, tourist cruise boats and other recreational craft.
Weirs
The basic objective of weir operations during regulated flow conditions is to maintain upstream ‘pool level’. Removing or replacing stop logs, which are concrete bars slid into slots on the weir pillars, can change this level. During flood periods the whole lock and weir structure becomes completely submerged and as a result there is no control over the water levels in the River.
Weirs do not control discharge but operate in response to variations of incoming flow to each structure. The weirs are not used to change flow within South Australia, only to maintain upstream pool levels.
Locks
A lock is a rectangular concrete chamber that is a controlled opening through which boats can pass. Each lock has 2 gates from which boats can enter either from upstream or downstream.
When a boat passes through the lock, the water inside the chamber must be at the same level as the top or bottom stream level, depending on the direction the boat is travelling. Water enters from the lock chamber through tunnels to the weir pool.
Boats are raised to upstream level or lowered to the downstream level as required. When the water in the lock is equal to the level of water in the weir pool, the gates can be opened and the boat can continue travelling.
<...Back to Top...>
When were the locks & weirs built?
River Murray Weirs and Locks
1. Blanchetown 1922
2. Waikerie 1928
3. Overland Corner 1925
4. Bookpurnong 1929
5. Renmark 1927
6. Murtho 1930
7. Rufus River 1934
8. Wangumma 1935
9. Kulnine 1926
10. Wentworth 1929
11. Mildura 1927
15. Euston 1937
26. Torrumbarry 1924
(Locks 12 to 14 and 16 to 25 were abandoned from the original plans to regulate the River) <...Back to Top...>
How much does the water levels change at the locks & weirs?
Each weir raises the level of water behind it by an average of 3.1 metres, to create a continuous series of stepped pools between Blanchetown and Mildura.
<...Back to Top...>
Why did they install the locks & weirs to regulate the river flows?
The River Murray in its natural state was an unreliable supplier of water and during droughts it could be reduced to a chain of saline ponds. A regulated river provided a reliable source of water and gave confidence in the Murray’s development. A succession of drought years from 1895 to 1902 emphasised the need for drought protections to enable further development in the Murray Valley.
In 1917 NSW, Victoria, SA, made available funding for the construction of weirs and navigational locks to regulate water flow and facilitate navigation and irrigation.
<...Back to Top...>
How have the river flows changed?
River flows are now regulated and therefore there is no seasonal flow and as a result summer flows are higher, winter flows are reduced and weirs upstream of SA have reduced the incidence of floods.
Present now are permanent wetlands and a slow flowing river, compared to temporary wetlands and occasionally fast flowing water before river regulation.
<...Back to Top...>
Information
Information sheets
Controlling the River Murray brochure
What’s What about River Operations and the River Murray, Fact Sheet 11, 1997 (also River Murray Urban Users Committee)
River Flows, Murray Mysteries, Information Sheet, 1998.
Murray Darling Association
The River Murray System: The Regulation and Distribution of River Murray Waters, MDBC, 1990.
Murray-Darling Basin Commission
River Murray Navigation, Murray Darling Basin Commission
Websites
Murray-Darling Basin Commission
<...Back to Top...>
|
