The River Path The River Path
Weirs and Sluices
Weirs were constructed to control the flow beside a mill or were the first point of diversion for a contouring leat taken off to power a downstream mill. Millers (a law unto themselves with "Miller's Rights") used sluices to increase the flow of water to their waterwheels by means of opening or shutting them (often leading to disputes with mill owners downstream). With the decline of milling, sluices are used to improve fisheries. In autumn / winter they are often raised to allow silt to be flushed away and to divert excess flood water by carriers onto flood meadows. In the summer the sluices can be lowered to impound water at times of low flow.
Where river engineering works have made rivers uniform, other artificial structures have been introduced to vary flows and habitats. Weirs may be used to create pools by the concentration of river flows, croys and groynes deflect the current in slow moving rivers to introduce diversity.
Pictures:
(left) Throop Mill, Bournemouth; (right) Pulteney Weir, Bath
