In the ninth of a series of articles looking at the developing plans for restoring Wanstead Park, Richard Arnopp of the Friends of Wanstead Parklands reflects on the recent River Roding flooding
This winter, nature gave Wanstead Park an unexpected but very welcome Christmas present. On 21 December, after days of very heavy rain, the water level in the River Roding rose to its highest level for some years and inundated the Ornamental Water. Within hours, the flood began to recede, but several years of low water levels had been resolved at a stroke, with the lake filled to capacity.
The River Roding sits in a huge valley, the relic of its past as a seasonal torrent during the last glaciation, carrying vast volumes of spring meltwater from the ice sheets just to the north. Nowadays, for most of the year, it is a placid little stream, but sometimes during the winter months, it shows something of its old mettle, with significant flooding occurring every decade or so.
The Roding and the Ornamental Water have a close historical relationship, which looks likely to be revived in a new form, as I shall explain.
Prior to the creation of the lake, the natural course of the river as it ran through Wanstead Park isn’t altogether certain, though an engraving of circa 1708 suggests that part of it roughly followed what became the eastern arm of the later Ornamental Water behind the islands. At this stage, there were also two artificial canals, which were later partly subsumed into the lake as it developed.
The Ornamental Water as we know it first appears on a plan of 1725, though construction may have begun up to a decade earlier. The new lake utilised elements of the water features already present and was directly fed by the river.
The water level was sustained by a system of weirs. The original plan of the lake was modified at various times, most radically by 2nd Earl Tylney of Castlemaine, but probably reached something like its present form around 1760.
Around this time, or slightly later, the Ornamental Water was severed from the river, which was canalised behind it. The average water level in the river is now about eight feet lower than in the lake when it is full, and the lake is retained by two brick-faced dams. The owners of Wanstead Park retained the right to temporarily dam the river to top up or flush out the Ornamental Water, and this right was exercised into the 20th century.
The purpose of canalising the River Roding may well have been to mitigate the flood risk upstream from the park. In 1768 a stone bridge, planned in 1752, had been built at Woodford. Almost immediately this was destroyed by floods and had to be rebuilt in 1771. Further canalisation of the river has taken place over the years, most recently in connection with construction of the Barking Relief Road.
As the Friends of Wanstead Parklands have explained in previous articles, discussions are being held with the Environment Agency to allow winter pumping from the River Roding into the Ornamental Water. However, as well as demonstrating the potential for winter spate pumping to manage lakes levels, the recent flood also fits into the evolving strategy of creating planned overflow areas to reduce potential flood risk for residents and businesses along the river.