The Great Flush

China's giant man-made waterfall as floodgates are opened to send millions of tons of silt downstream

It is an scene of almost apocalyptic proportions. Bystanders are dwarfed as they stand watching a tremendous rush of water gushing through gaps in a dam in China, part of a carefully-choreographed operation to remove silt from the Yellow River in Luoyang, in the Henan province.

This annual operation sees more than 30 million tonnes of silt sent downstream a year, with more than 390 million tonnes shifted this way over the last 13 years. The silt-carrying water gushes out of three specialised holes in the dam of the Xiaolangdi Reservoir on the Yellow River during the annual silt-washing operation.

The Yellow River authority says such operations lowers the river bed in the lower reach of the river by an average of 2.03 meters each year.

The dam stands at 154m (505ft) tall and is 1,317m (4,321ft) wide. When it was built opened in 2000, following a six-year construction, it had cost US$3.5billion to construct.

The dam also produces almost 1.8 gigawatts of power, approximately the equivalent of nearby (to me) Calvert Cliffs Nuclear Power Plant (1.7 gigawatts). While it does have to be refueled annually, at least you don't have to flush 400 millions tons of silt out of it.

The Colorado River at Glen Canyon Dam (Hoover Lake) also benefits from a similar flushing program.  Instituted back in 2008, after years of regulated flows had allowed the river to silt heavily,  it was only partially successful in restoring a more natural river regime downstream. 

Maybe doing this with Susquehanna at Conowingo Dam could restore the Upper Bay to level required to support Atlantic Sturgeon reproduction, thought to be inhibited by the sedimentation.