River Dearne - Flood Defences

Flood Defences

By the 1950s, the course of the river near its mouth had been affected by subsidence from coal mining, and the lowering of the channel resulted in much of the surrounding land being regularly flooded. In order to alleviate the problem and restore the gradient of the channel at this point, a new channel was constructed on the south side of the railway embankment, from near Harlington to the River Don. The old channel can still be seen on the north side of the embankment, and connects to the Denaby Ings Nature Reserve.

As part of a comprehensive assessment of flood risks caused by the River Don and its tributaries, the River Dearne Improvement Scheme was implemented between 1963 and 1973. It was recognised that simple enlargement of the river channel would not provide a satisfactory solution, as it would just move the problem to the River Don, and therefore a series of washlands were created, which could be progressively flooded if required, without affecting centres of population. Near the mouth of the river, Dearne Mouth washland, which is now known as the Denaby Ings Nature Reserve, was created in 1963, and a manually operated sluice allowed the flow of the river to be diverted through the floodbank and into the washland when there were high levels at the junction with the River Don. The sluice was rebuilt in 1973. Additional washlands were created at Harlington and North Ings, and the river was straightened and realigned.

Further upriver, a flood relief channel was built at Bolton upon Dearne, and more washlands were formed between Wath railway bridge and Adwick bridge. The Bolton Ings and Old Moor washlands were next to be created, to be followed by those at Wombwell Ings, where the River Dove joins the Dearne, Darfield, Houghton and Cudworth. Some of the storage capacity was lost as a result of mining schemes, and a regulator was installed at Bolton in 1972, allowing the flow to be restricted by a sluice gate. During the flooding in 2007, all of the washlands filled to capacity, although the Bolton regulator could not be operated as it had been vandalised. Some damage to the Houghton washlands resulted from the extremely high water levels, which overtopped the banks and caused erosion to take place. Following the floods, a reassessment of the function of the regulators was carried out, and in view of the costs of maintaining them, the Environment Agency intend to remove them once some reconfiguration of the river channel has been completed. This work will ensure that the washlands fill and empty at the appropriate points in a flood cycle.