Somerset Levels - Drainage

Drainage

The Moors and Levels are formed from a submerged and reclaimed landscape. Early attempts to control the water levels were possibly made by the Romans (although records only date from the 13th century), but were not widespread.

There was a port at Bleadney on the River Axe in the 8th century which allowed goods to be brought to within 3 miles (5 km) of Wells. In 1200, a wharf was constructed at Rackley near Axbridge. The Parrett was navigable up as far as Langport in 1600, with 15 to 20 ton barges. The Domesday Book recorded that drainage of the higher grounds was under way, although the moors at Wedmoor were said to be useless. In the Middle Ages, the monasteries of Glastonbury, Athelney, and Muchelney were responsible for much of the drainage. In 1129, the Abbot of Glastonbury was recorded as inspecting enclosed land at Lympsham. Efforts to control flooding on the Parrett were recorded around the same date. In 1234, 722 acres (2.9 km2) were reclaimed near Westonzoyland and, from the accounts in the abbey's rent books, this had increased to 972 acres (393 ha) by 1240. Flooding of adjacent moor land was partially addressed during the 13th century by the construction of a number of embankment walls to contain the Parrett. They included Southlake Wall, Burrow Wall, and Lake Wall. The River Tone was also diverted by the Abbot of Athelney and other land owners into a new embanked channel, joining the Parrett upstream from its original confluence.

The main drainage outlets flowing through the Moors and Levels are the rivers Axe, Brue, Huntspill, Parrett, Tone, and Yeo, together with the King's Sedgemoor Drain, an artificial channel into which the River Cary now runs. Previously, the Cary ran into the Tone while the Brue ran through Meare Pool (now drained) and the Panborough Gap, and then into the Axe. Another accomplishment in the Middle Ages was the construction of the tidal Pillrow Cut, joining the Brue and Axe. In 1500, there was said to be 70,000 acres (283 km2) of floodable land of which only 20,000 acres (81 km2) had been reclaimed. In 1597, 50 acres (20 ha) of land were recovered near the Parrett estuary; a few years later, 140 acres (57 ha) near Pawlett were recovered by means of embankments; and three further reclamations, totalling 110 acres (45 ha), had been undertaken downstream of Bridgwater by 1660.

In the early 17th century, during the time of King James I, abortive plans were made to drain and enclose much of Sedgemoor, which the local Lords supported but opposed by the Commoners who would have lost grazing rights. In 1632, Charles I sold the Crown's interest in the scheme, and it was taken over by a consortium that included Sir Cornelius Vermuyden, a Dutch drainage engineer. However, the work was delayed by the English Civil War and later defeated in parliament after local opposition. In 1638, it was reported that nearly 2,600 acres (11 km2) of Tealham and Tadham Moors were not reclaimed, with a total of 30,500 acres (123.43 km2) being undrained. Between 1785 and 1791, much of the lowest part of the peat moors was enclosed. In 1795, John Billingsley advocated enclosure and the digging of rhynes (a local name for drainage channels, pronounced "reens" in the east and rhyne to the west) between plots, and wrote in his Agriculture of the County of Somerset that 4,400 acres (18 km2) had been enclosed in the last 20 years in Wedmore and Meare, 350 acres (1.4 km2) at Nyland, 900 acres (3.64 km2) at Blackford, 2,000 acres (8 km2) at Mark, 100 acres (0.4 km2) in Shapwick, and 1,700 acres (7 km2) at Westhay. At Westhay Moor in the early 19th century, it was shown how peat bogs could be successfully drained and top-dressed with silt deposited via flooding, creating a very rich soil. The character of the soil was also changed by the spreading of clay and silt from the digging of King's Sedgemoor Drain.

Little attempt was made during the 17th and 18th centuries to pump water, possibly because the coal-driven Newcomen steam engines would have been uneconomical. It is unclear why windmills were not employed, as they were on The Fens of East Anglia, but only two examples have been recorded on the Levels: one at Bleadon at the mouth of the River Axe, where a sea wall had been built, and the other at Common Moor north of Glastonbury, which was being drained following a private Act of Parliament in 1721. The first steam pumping station was Westonzoyland Pumping Station in 1830, followed by more effective ones from 1860. Automatic electric pumps are used today.

The man-made Huntspill River was constructed during the Second World War with sluices at both ends to provide a guaranteed daily supply of 4,500,000 imperial gallons (20,000,000 l; 5,400,000 US gal) of "process water". It was intended that in the summer, when water supply was lower, it would serve as a reservoir with water pumped from the moors; and in winter serve as a drainage channel, via gravity drainage. Geotechnical problems prevented it from being dug as deep as originally intended and so gravity-drainage of the moors was not possible: thus, water is pumped up into the river throughout the year. The Sowy River between the River Parrett and King's Sedgemoor Drain was completed in 1972. The Levels and Moors are now artificially drained by a network of rhynes which are pumped up into "drains". Water levels are managed by the Levels internal drainage boards (IDBs); the Levels are not as intensively drained or farmed as the East Anglian fens, historically a similar area of low marsh. They are still liable to widespread fresh water flooding in winter. One of the approaches to reducing the risk of flooding within the catchment area of the Parrett is the planting of new woodlands.

Controversy about the management of the drainage and flood protection has previously involved the activities of IDBs. However, IDBs have been actively participating with the Parrett Catchment Partnership, a partnership of 30 organisations that aims to create a consensus on how water is to be managed, in particular, looking at new ways to achieve sustainable benefits for all local stakeholders.

During 2009 and 2010, work was undertaken to upgrade sluice gates, watercourses, and culverts to enable seasonal flooding of Southlake Moor during the winter diverting water from the Sowy River onto the moor. It has the capacity to hold 1.2 million cubic metres as part of a scheme by the Parrett Internal Drainage Board to restore ten floodplains in Somerset. In spring, the water is drained away to enable the land to be used as pasture during the summer. The scheme is also used to encourage water birds.