Sunrise over the River Yare by Elizabeth Dack
River Thurne by Craig Humphries
The frozen river Thurne by Yvonne Magill
Norfolk’s rivers may be divided into three catchments. In the west and south west are rivers which feed into the Great Ouse and flow to sea through the Wash. These include the Thet, Little Ouse and Wissey, and they are joined in the final reach of the Great Ouse by the Nar and the Gaywood. A huge area of the centre, south and east of Norfolk is drained by rivers which flow to sea through Breydon Water in the Broads. The principal rivers here include the Waveney, Yare, Wensum, Bure, Ant and Thurne, though they have many tributaries. In the north and the north west of the county a few small rivers, including the Burn, Stiffkey, Glaven and Mun flow directly into the Wash or the North Sea without joining a larger river’s catchment.
Each of these rivers has a unique course and unique interactions with other habitats and human land use. Broadly speaking, however, though Norfolk has no significant uplands, the upper reaches of our rivers are swift and often chalky and the lower reaches are muddier, more sluggish and often strongly affected by tidal incursions. The effect of the tide on our rivers is illustrated by the fact that marine fish have been found as far up the Wensum as Norwich.
During the middle of the twentieth century Norfolk’s rivers suffered gravely from contamination from agricultural run-off, tourism in the Broads, and to a lesser extent industry. For several decades the county’s rivers suffered from eutrophication – the over-availability of nutrients – as a result of the presence of raised levels nitrates from agricultural fertilisers and phosphates from sewage. Eutrophication frequently leads to blooms of algae which shade out other plants and may be toxic to animal life. Thanks to stricter controls, the water in Norfolk’s rivers is now much cleaner, with the result that they are again attractive and biologically diverse.