Weir Operation

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. These stop logs can be removed during floods. 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

Source: MDBC

Lock Operation

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. It takes only 7 minutes to empty or fill the lock chamber but it normally takes 15 to 20 minutes to pass a boat through the lock. Six to 8 medium houseboats can be accommodated in one lockage.

Source: MDBC

Content sourced from Majestic Murray User Guide 2nd Edition 2001

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