Water head
Culvert, screen and outfall manual, (CIRIA C786) published by CIRIA in 2019, defines ‘head’ as: ‘The total energy per unit weight of fluid expressed in metres of water above a datum.’
Head loss is: ‘The difference in head between two points due to friction or other features that result in energy loss (eg a transition, step, construction, expansion or bend).’
Headroom is the: ‘Vertical gap between the water surface and the roof (soffit) of a culvert or outfall to allow for floating debris (also known as air draught).’
Headwater depth is: ‘The depth of water above culvert invert at the culvert inlet.’
Headwater elevation is: ‘The depth of water above datum at the culvert inlet.’
Headwater ratio is: ‘Specific energy of headwater divided by barrel height.’
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