Editing River Derwent, Yorkshire (section)

==Barmby Barrage==
Water from the [[tidal river|tidal River]] Ouse is prevented from entering the Derwent by means of a barrage at Barmby on the Marsh.<ref name=Danby/> The Derwent has been kept non-tidal since the 1970s because water is abstracted at [[Loftsome Bridge|Loftsome Bridge water treatment works]] to supply the City of [[Kingston upon Hull|Hull]].
The barrage has a navigation lock and two sluice gates. The objectives of the barrage are:
# to exclude the waters of the Ouse from the Derwent
# to maintain a depth of water for navigation and abstraction
# to keep the river level low enough to permit drainage from the surrounding land.
The barrage has two sluice gates, each is 7 metres wide and 5 metres high. They are raised and lowered by ropes from winches mounted in a machine room in the centre of the barrage. To travel the 5 metres from the fully closed to the open position of the gates takes 10 minutes. There is a [[Programmable logic controller|PLC]] system to control the opening and closing of the gates which incorporates river level sensors, gate position sensors and a motor control centre.
On a rising tide in the River Ouse the gates are closed and they are only allowed to open again once the level of the Ouse has fallen below that of the Derwent. An electronic communications link provides data remotely to the UK Environment Agency.<ref name=CAMS/><ref name=Idec>{{cite web|url=http://www.idec.ltd.uk/?atk=61 |title=Barmby Barrage |access-date=25 March 2008 |year=2006 |publisher=Idec Technical Services }}</ref>