Water-meadow

A water-meadow (also water meadow or watermeadow) is an area of grassland subject to controlled irrigation to increase agricultural productivity. Water-meadows were mainly used in Europe from the 16th to the early 20th centuries. Working water-meadows have now largely disappeared, but the field patterns and water channels of derelict water-meadows remain common in areas where they were used, such as parts of Northern Italy, Switzerland and England. Derelict water-meadows are often of importance as wetland wildlife habitats.

Water-meadows should not be confused with flood-meadows, which are naturally covered in shallow water by seasonal flooding from a river. "Water-meadow" is sometimes used more loosely to mean any level grassland beside a river.

Two main types of water-meadow were used.

These were used for fields on slopes, and relatively little engineering skill was required to construct them. Water from a stream or spring was fed to the top of a sloping field, and gentle sloping terraces were formed along which the water could trickle in a zig-zag fashion down the field. The water could be used again for fields lower down the slope.

Bedwork or floated water-meadows were built on almost-level fields along broad river valleys, and required careful construction to ensure correct operation.

A leat, called a main, carrier or top carrier, was used to divert water from the river and carry it down the valley at a gentler slope than the river, producing a hydrostatic head between the two. Mains were often along the edge of the valley, each main supplying up to about 1 km (0.6 mi) of the valley. The water from the main was used to supply many smaller carriers, on the crests of ridges built across the fields. The channel on the crest of each ridge would overflow slowly down the sides (the panes) of the ridge, the channel eventually tapering to an end at the tip of the ridge. The seeping water would then be collected between the ridges, in drains or drawns, these joining to form a bottom carrier or tail drain which returned the water to the river. The ridges and the drains made an interlocking grid (like interlaced fingers), but the ridge-top channels and the drains did not connect directly. A by-carrier took any water not needed for irrigation straight from the main back to the river. The ridges varied in height depending on the available head – usually from around 10 to 50 cm (4 to 20 in). The pattern of carriers and drains was generally regular, but it was adapted to fit the natural topography of the ground and the locations of suitable places for the offtake and return of water.

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