Falconbrook

The Falconbrook, a south west London brook, now underground for its entire length, has been throughout replaced by surface water drains diverting water away; its course forming a very slight depression is used from its source for a conveniently cheap, Victorian, anti-environmental solution — a combined sewer — to the Southern Low Level Sewer in the London sewerage system. The source of the Falconbrook is Streatham Hill, with an additional source to the west at Furzedown south of Tooting Bec Common. From its source the Falconbrook flowed west through Balham, then turned north one residential block before Wandsworth Common as it was joined by the Tooting Bec and continues to carve a ravine which is formed by St John's Road and Northcote Road in Battersea Rise. Springs feeding the first drain underneath the foundations of a row of shops (nos 2–36 Streatham High Road, the A23 road). During their construction, extra access space was built below the basement floors to accommodate the springs when in full spate. The brook flowed (and now sewer flows) along Drewstead Road, past Woodfield Avenue, passed through the north of Tooting Bec Common, north down Cavendish Road (passing Weir Road), west along the approximate line of Kenilford Road, along Oldridge Road, turned north by Holy Ghost School, west of Rusham and Montholme Road and along Northcote Road, 8-11m AOD.[2][3] After St John's Road it flowed along Falcon Road, Battersea just before its end turned west emptying in the River Thames west of Lombard Road and north of the London Heliport.[2]

The Manor of Battersea was owned from about 1627 to 1763 by the St John baronets, of Lydiard Tregoze, who latterly became the Bolingbroke Viscounts.[4] The supporters of the armorial bearings of the St John family were a falcon wings displayed Or, or, more plainly, a pair of golden falcons displaying their wings. The Falcon brook and similarly named features in the locality - Falcon Park, Falcon Road, "The Falcons" housing estate, the Falcon pub, and the Falconbrook Primary school.[3] - have named derived from this display of heraldry.[5]

Falconbrook's catchment basin, unlike longer tributaries such as the Lea and Wandle is entirely based on impermeable to semi-impermeable London Clay, starting north of areas with remaining Lambeth Group and North Downs topsoil.[6]

Ponding of the "Falcon Brook" has been recorded as early as 1745.[7] An entirely London Clay catchment basin and flatter lower course through Battersea was, before urbanization, a major factor contributing to the stream's overflow. Now separate surface water and sewerage systems are in place and are sufficient to drain many parks, roofs and roads in an attempt to intercept the sewerage system before polluting the Tideway. A further interceptor pipe the Thames Tideway Scheme is expected to be completed by 2023 to avoid overflow.[8]

Thames Water carried out work at the end of 2006 to resolve the flooding of the Falconbrook sewer in the north of Balham, involving a series of road closures.

In July 2007, demonstrating response to rainfall due to a combined sewer function, the Falconbrook sewer burst out of the pavement in several places and flooded Falcon Road by Clapham Junction, during the 2007 floods. Since 2007, five incidents have been recorded of flooding in the Critical Drainage Area 7/21 that covers that area.[8][9]

• Tributaries of the River Thames
• List of rivers in England