River Avon, Bristol
The River Avon is a river in the southwest of England. To distinguish it from a number of other rivers of the same name, it is often called the Bristol Avon. The name 'Avon' is loaned from an ancestor of the Welsh word afon, meaning 'river'.
The Avon rises just north of the village of Acton Turville in South Gloucestershire, before flowing through Wiltshire into Somerset. In its lower reaches from Bath to the Severn Estuary at Avonmouth near Bristol, the river is navigable and is known as the Avon Navigation.
The Avon is the 19th longest river in the United Kingdom, at, although there are just as the crow flies between the source and its mouth in the Severn Estuary. The catchment area is.
Etymology
The name "Avon" is loaned from the Common Brittonic abona, "river", which survives in the Welsh word afon. "River Avon", therefore, literally means "river river"; several other English and Scottish rivers share the name. The County of Avon that existed from 1974 to 1996 was named after the river, and covered Bristol, Bath, and the lower Avon valley.Course
The Avon rises on the southern edge of the Cotswold hills, at Didmarton in Gloucestershire; at Joyce's Pool a plaque marks the source. It flows south-east into Wiltshire to Sherston, where it is joined by the Luckington Brook which drains an area west of Luckington that includes the Badminton House estate.From Sherston the river flows east to Malmesbury, where it is joined by its first major tributary, the Tetbury Avon, which rises just east of Tetbury in Gloucestershire. This is known locally as the Ingleburn, which in Old English means 'English river'. The two rivers flow north and south of a rocky outcrop, almost creating an island for the ancient hilltop town of Malmesbury to sit on. Upstream of this confluence the river is sometimes referred to as the 'River Avon ' to distinguish it from the Tetbury branch.
At the point where the two rivers merge, the Avon turns southeast away from the Cotswolds and then quickly south into the clay Dauntsey Vale, where it is joined by the River Marden, until it reaches the biggest town so far, Chippenham. The wide vale is now known as the Avon Vale, and the river flows on via Lacock to Melksham, then turns north-west through Bradford-on-Avon, where the centre of the town grew up around a ford, hence the origin of the town's name. This was supplemented in Norman times by the Grade I listed bridge that still stands today; originally a packhorse bridge, it was widened in the 17th century by rebuilding the downstream side.
The Avon Valley between Bradford-on-Avon and Bath is an example of a valley where four forms of ground transport are found: road, rail, river, canal. The river passes under the Avoncliff and Dundas Aqueducts which carry the Kennet and Avon Canal, and at Freshford is joined by the Somerset River Frome. Avoncliff Aqueduct was built by John Rennie and chief engineer John Thomas, between 1797 and 1801. The aqueduct consists of three arches and is long with a central elliptical arch of span with two side arches each semicircular and across, all with V-jointed arch stones. The spandrel and wing walls are built in alternate courses of ashlar masonry, and rock-faced blocks. The central span sagged soon after it was built and has been repaired many times. The Dundas Aqueduct was built by the same team between 1797 and 1801 and completed in 1805. James McIlquham was appointed contractor. The aqueduct is long with three arches built of Bath Stone, with Doric pilasters, and balustrades at each end. The central semicircular arch spans ; the two oval side arches span. It is a Grade I listed structure, and was the first canal structure to be designated as a Scheduled Ancient Monument in 1951. The stretch of river below and above the aqueduct, where it is joined by Midford Brook, has been used by rowing crews from Monkton Combe School since at least the beginning of the 1900s.
It then flows past Claverton Pumping Station, which pumped water from the River Avon by Warleigh Weir into the canal, using power from the flow of the river. The pumping station is located in a pump house built of Bath Stone, located at river level. Water is diverted from the river by Warleigh Weir, about upstream. The water flows down a leat to the pumping station, where it powers a water wheel, wide and in diameter, with 48 wooden slats. At full power the wheel uses 2 tons of water per second and rotates five times a minute. The water wheel drives gearing which increases the speed to 16 rpm. From here, cranks drive vertical connecting rods which transfer the energy to two long cast iron rocking beams. Each rocking beam in turn drives an 18 in diameter lift pump, which also take their supply from the mill leat. Each pump stroke raises of water to the canal. In 1981, British Waterways installed two electric pumps just upstream from the station.
File:Pulteney bridge in Bath view from south before noon.jpg|alt=A three arch stone bridge with buildings on it, over water. Below the bridge is a three step weir and pleasure boat.|thumb|left|Palladian Pulteney Bridge and the weir at Bath
The Avon then flows through Bathford, where it is joined by the Bybrook River, and Bathampton where it passes under the Bathampton Toll Bridge. It is joined by the Lam Brook at Lambridge in Bath and then passes under Cleveland and Pulteney Bridges and over the weir.
Cleveland Bridge was built in 1826 by William Hazledine, owner of the Coalbrookdale Ironworks, with Henry Goodridge as the architect, on the site of a Roman ferry crossing. Named after the 3rd Duke of Cleveland, it spans the River Avon at Bathwick, and enabled further development of Georgian Bath to take place on the south side of the river. It was designed by architect Henry Goodridge to take the traffic of his day, horse-drawn vehicles and pedestrians, and was constructed using Bath Stone and a cast iron arched span.
Pulteney Bridge was completed in 1773 and is designated by English Heritage as a Grade I listed structure. The bridge was designed by Robert Adam, and is one of only four bridges in the world with shops across the full span on both sides. It is named after Frances Pulteney, heiress in 1767 of the Bathwick estate across the river from Bath. Floods in 1799 and 1800 wrecked the north side of the bridge, which had been constructed with inadequate support. It was rebuilt by John Pinch the Elder, surveyor to the Pulteney estate, in a less ambitious version of Adam's design. Bath and North East Somerset council have discussed plans to ban vehicles from the bridge and turn it into a pedestrianised zone, but it remains open to buses and taxis.
Some 700 metres below Pulteney weir, the river is joined by the Kennet and Avon Canal which connects through Bath Locks. Together with the Kennet Navigation which joins the River Thames at Reading, this provides a through route for canal boats from Bristol to London. From this point downstream the river is known as the Avon Navigation.
Navigation
The Avon above Bath remains navigable as far as Bathampton where there is the remains of a flash lock. However, the lock past the weir below Pulteney Bridge was demolished when the weir was reconstructed, so passage between the sections is only possible for dinghies and canoes using the roller slipway on the side of the weir.Beyond its junction with the Kennet and Avon Canal, the Avon flows through Keynsham towards Bristol. For much of its course after leaving Wiltshire, it marks the traditional boundary between Somerset and Gloucestershire. For most of this distance the navigation makes use of the natural riverbed, with six locks overcoming a rise of. From Bath to Netham Lock where it divides into the New Cut and the Floating Harbour is. The stretch is made navigable by the use of locks and weirs.
In the centre of Bath it passes under various bridges, including the Midland Bridge which was built by the Midland Railway Company to allow the Somerset and Dorset Joint Railway access to and from its Green Park terminus station. In November 2011, the navigation between Bath and Bristol was closed because of safety concerns about Victoria Bridge. Weston Lock on the outskirts of Bath is in what now forms the Newbridge area. Weston Cut is a man made channel, opened in 1727, for boats to approach and pass through Weston Lock; the island created between the cut and the river weir became known as Dutch Island after the owner of the brass mill established on the riverside in the early 18th century.
Kelston Lock and weir have permanent moorings above and below them. The Riverside Inn and Saltford Marina are also close by. Saltford Lock and weir are overlooked by the remains of the Kelston Brass Mill, which was working until 1925. It is a Grade II listed building. Alongside the lock is a pub, whose garden extends over the lock to the small island between the lock and weir. The lock was opened in 1727 and destroyed in 1738 by rival coal dealers to stop the use of the river for transportation. In its heyday, between 1709 and 1859, Swineford had an active brass and copper industry around Swineford Lock, served by the river which also provided water power for the cloth industry, as did the River Boyd, a tributary which flows into the Avon near Bitton. Keynsham Lock opened in 1727. Just above the lock are visitor moorings and a pub, on an island between the lock and the weir. The weir side of the island is also the mouth of the River Chew. The river is joined by the Siston Brook at Londonderry Wharf, terminus of the dramway which brought coal from Coalpit Heath. The final river lock, Hanham Lock, is on the edge of the Bristol built-up area; below here the river is affected by high tides which overtop Netham Weir. Above the weir, in the St Anne's area of Bristol, the river is joined by Brislington Brook.
Netham Lock is the point at Netham in Bristol at which boats from the Avon gain access to Bristol's floating harbour. Construction started in 1804 to build the tidal New Cut, where it is joined by the River Malago, and divert the Avon along the Feeder Canal to the harbour; a system designed and built by William Jessop and later improved by Isambard Kingdom Brunel. A weir carries the river into the New Cut and boats use the adjacent lock. Access to the harbour is only possible during the day, when the lock keeper will open the gates unless the water level in the river between Netham and Hanham is above or below the level of the harbour. Netham Lock and the weir form part of Bristol's flood defence mechanisms.
File:River Avon at Welsh Back Bristol.jpg|alt=The view north from Redcliffe Bridge, showing one yellow water taxi, warehouses and various buildings along Welsh Back|thumb|The River Avon in Bristol, looking towards Bristol Bridge with Welsh Back on the left. Boats of the Bristol Ferry Company are moored in the foreground, and the spires of St Nicholas, All Saints' and St Mary le Port churches can be seen in the distance.
In central Bristol, where the river is tidal, it is diverted from its original course into the New Cut, a channel dug between 1804 and 1809 at a cost of £600,000. The original course is held at a constant level by lock gates and is known as the floating harbour, since it enables ships to stay afloat rather than grounding when the tide ebbs. The harbour is protected by an 1870s replacement for Jessop's locks. This unusual dock has a tentacled plan resulting from its origins as the natural river course of the Avon and its tributary, the River Frome, and is intimately entwined with Bristol's city centre as few docks are. As a result of this, the floating harbour is one of the more successful pieces of dockland regeneration, with much of the dockside now occupied by residential, office and cultural premises, and the water heavily used by leisure craft. Downstream of central Bristol, the river passes through the deep Avon Gorge, spanned by Brunel's Clifton Suspension Bridge: the river is tidal and is navigable by seagoing vessels at high tide but dries to a steep-sided muddy channel at low tide. It was largely the challenge of navigating this section that sealed the fate of the floating harbour as commercial docks, and saw them replaced by docks at Avonmouth where the Avon joins the Severn Estuary.
Before reaching its mouth, the Avon is joined by the River Trym at Sea Mills which was the site of Portus Abonae, a Roman port. Shortly after, it passes the village of Pill on the south bank where the Pill Hobblers were based in order to tow ships up the river to Bristol and where yachts and other boats still have moorings in Chapel Pill and Crockerne Pill. It then passes under the Avonmouth Bridge which carries the M5 motorway. The main span is long, and the bridge is long, with an air draught above mean high water level of. The river then serves two major dock areas. The Royal Portbury Dock is on the southern side of the mouth of the river. The deepwater dock was constructed between 1972 and 1977, and is now a major port for the import of motor vehicles. The Royal Portbury Dock has the largest entrance lock into any UK port, accommodating vessels up to beam, length and draft. The Avonmouth Docks are on the north side of the river and are one of the UK's major ports for chilled foods, especially fruit and vegetables. The first dock at Avonmouth, Avonmouth Old Dock, was opened in 1877 and acquired by Bristol Corporation in 1884. In 1907, a much larger dock, the Royal Edward Dock, was opened. The docks form part of the Port of Bristol and were operated by the Port of Bristol Authority, part of Bristol City Council, until 1991 when the council granted a 150-year lease to the Bristol Port Company. Pilotage is provided by Bristol Pilots LLP who supply authorised pilots for the River Avon and Bristol City docks, as well as the Severn estuary and the Bristol channel; they are based at Avonmouth Docks.