Like their counterparts elsewhere in the world, Australian engineers gaily pockmarked the basin with dams, weirs and locks, with little thought for what that would do downstream.By the 1990s the drawbacks were evident.
The construction of fish ladders around dams and weirs, and the release of extra water into important breeding grounds, has spawned a recovery in native species.
A rapidly built network of dams and weirs, and massive amounts of gypsum and acetic acid, have stemmed or at least neutralised the tide of toxic waste that hit the river after a reservoir wall gave way at the MAL Zrt aluminium plant at Ajka, in western Hungary, on October 4th.
The flow of rivers is regulated by weirs and dams.
Pöyry Energy, based in Switzerland, and the French Compagnie Nationale du Rhône are trying to convince Cambodia, Vietnam and other sceptics that the Xayaburi dam will be benign.Both firms argue that "fish passes" or weirs can be built to enable 85% of the river's fish to get past the dam's turbines.
Guo Shoujing, a 13th-century scientist, is still revered for designing a network of lakes, weirs and waterways.
They have also built stone weirs across these canals at regular intervals, to slow the current down still further and encourage water to spill over the canal banks.
Sometimes both weirs and pipes are provided.
In 1843 it was decided to build a series of diversion dams (barrages or weirs) across the Nile at the head of the delta about 12 miles downstream from Cairo, so as to raise the level of water upstream to supply the irrigation canals and to regulate navigation.
Hydraulic jump, Sudden change in water level, analogous to a shock wave, commonly seen below weirs and sluice gates where a smooth stream of water suddenly rises at a foaming front.
Clarified effluent (water flowing out) is skimmed from the surface as it flows over special baffles called weirs.
