The Ravensbourne is a spring-fed stream that rises to the south of Keston at Caesar’s Well (TQ 417637) on the north (dip) slope of the North Downs and flows northwards through the boroughs of Bromley, Lewisham and Greenwich to join the Thames at Deptford Creek. The main rivers in the catchment are the Ravensbourne, as the main branch, the Quaggy (E) and the Pool (W). The geomorphology reveals large areas of
The Ravensbourne Catchment (Flickr 2010)
underlying pebbly Blackheath beds and smaller areas of underlying sandy Woolwich and Reading beds in places (EA 1996).
While the main branch of the Ravensbourne rises in Keston there is an eastern branch rising at Nobody’s Wood at Locks Bottom, this is the Kyd Brook. The confluence of the main and eastern branch is just below Mason’s Hill in Bromley. The length of this watercourse is 25kms. The Kyd Brook tributary draining the eastern flank becomes the Quaggy at Sundridge Park before joining the Ravensbourne at Lewisham High Street, the confluence being by the bus station (see Fig 2), and the total length of this system is 23kms. The Pool River, including the Chaffinch and the Beck, drains the western flank of the catchment, rising at Addington and entering the Ravensbourne at Catford (see Fig 6). The total length of this system is approximately 19kms. According to the EA report in 1996, the heavily engineered concrete channels and toeboarding sections make up 30kms of the 66kms of channel (EA 1996), however since the ‘daylighting’ of the river at Chinbrook Meadows, Sutcliffe Park etc, this ratio has altered. As is typical for any urban river, flows following rain events are dictated by run-off from tarmac, paved streets and walkways. The dense urbanisation within the Ravensbourne catchment ensures a fast return of rainfall into streams and gullies feeding the main branch.
Serious flooding has not occurred in Lewisham since 1968 (Fig 9), when Lewisham and Catford town centres were affected. Previous flood events occurred in 1928 and 1965 with the 1928 flood the product of overtopping from the Thames (EA 2010). The last flood was in 1992 when 50 properties along the Quaggy at Lee were affected (EACE 2009).