About

While many consider the Tidal Thames to be Londons iconic river, only non-tidal tributaries belong to the London Management Catchment, which covers eight separate river systems. Three (Brent, Crane, and Lower Lee) lie north of the Thames, with another five south of the River: the Hogsmill, Beverley Brook, Wandle, Ravensbourne and Marsh Dykes. There are also numerous lost rivers in central London that run underground in culverts, having been incorporated into the Victorian sewer network. Typically, the rivers rise in the rolling hills and relatively open spaces of rural or suburban areas around the outskirts of London. As they flow towards the Thames, they pass through increasingly built-up areas, with dense housing development and industrial estates often built right to the rivers edge. The catchment area is intersected by roads and railways. This dense urban development has resulted in major modifications to most rivers, and serious pollution problems. Nevertheless, in many places the rivers serve as valuable green corridors leading into the heart of the capital and connecting city-dwellers with nature. Groundwater is mainly contained in chalk aquifers beneath a layer of clay, but in the south the rivers have their sources in the groundwater springing from a chalk ridge. At 1487 km the London management catchment is relatively small, but has by far the largest population of any management catchment, with complex, intertwined and conflicting socio-economic pressures. It covers roughly 70% of the Greater London area, extending into Hertfordshire and Essex in the north, and Surrey in the south.