Context 170 - December 2021

12 C O N T E X T 1 7 0 : D E C E M B E R 2 0 2 1 PETER BROWN The Severn navigation Although Thomas Telford complained that it was too dry in droughts and too prone to flood in the rainy season, the Severn was a major transport route for millennia. The Severn is a young river. Before the last ice age the river ran north from Wales to the Dee. The ice blocked that route and a large lake was created in central Shropshire which, when it drained, cut the Severn Gorge past Ironbridge. From Welshpool down past Shrewsbury to the entrance to the Gorge, the river meanders and is fairly shallow. Through the Gorge and on down to Stourport, it has a succession of pools, stretches where the water is deep and flows slowly, and riffles, where it runs rapidly across pebbly shallows, these being most concentrated in the Gorge.Through the ‘Middle Severn’, from Stourport to Gloucester, it is joined by other rivers with significant water flows, principally the Stour, Salwarpe, Teme and (Warwickshire) Avon; below Tewkesbury it is increasingly tidal. Below Gloucester the river is a winding estuary, the site of the country’s most spectacular bore at spring tides. The Severn is prone to flooding, especially early in the year when the snows melt in central Wales. In 1797 Thomas Telford wrote that an impediment to navigating the Severn was ‘the deficiency of the water in droughts and... the superabundance of it during rainy seasons’. The problem had got worse, which he attrib- uted to the raising of riverside embankments in Montgomeryshire and Shropshire, with the flood water no longer flowing on to washlands, then coming slowly off as the water subsided. The liability to flooding had one indirect ben- efit for navigation: the Severn, unlike, say, the Thames, was not suitable for the construction of watermills and their associated dams. Instead, the watermills were built on the streams which entered the river.Thus the Severn was navigable, water levels permitting, all the way up to Pool Quay, three miles short of Welshpool. The principal man-made obstructions on the Severn were fish-weirs.Typically these comprised a wattle fence, supported by timber braces and piles, running across the river to form V-shaped funnels pointing downstream, with a bag-like net at the apex of the funnel in which to catch the fish, principally eels. Over 40 are known to have existed in Shropshire alone, although not all at the same time. The weirs either did Bewdley was one of the principal up-river ports on the Severn. (Photo: Tanya Dedyukhina, Wikimedia)