The Mayor of London launched a consultation on Sustainable Urban Drainage in 2015. Robert Holden and Tom Turner discuss the issues, in the above video, and make the following points:
- London needs an integrated water plan for surface water drainage, river reclamation, water supply, aquifer recharge and protection against both sea and river flooding. This will involve both engineering and urban landscape design.
- The Mayor should consider the establishment of a College of Advisors for Architecture, Engineering and Landscape following the example of the Netherlands College of Advisors. Dirk Sijmons was the landscape architect who led production of the Dutch National Waterplan in 2009
- Landscape architects have a particular role to play in water and vegetation plans for roofs, streets, gardens, and greenspace.
- Roofs: (1) It should be a planning condition that flat roofs in new development are vegetated (2) Existing flat roofs should be vegetated with financial support in the forms of grants or business rate and council tax rebate (so following German and Swiss precedent).
- Streets and footpaths: London needs permeable paving and rain streets
- Gardens: private gardens should incorporate rain gardens to detain and infiltrate surface water runoff
- Greenspace: public and private greenspace should contribute to urban surface water management
- Pilot projects: The first step towards the development of a London vegetation and water strategy should be a set of local pilot projects in varied geological, urban and topographic conditions. As green engineering projects they can be compared with the Mayor’s mini-Holland projects for making London a cycling city. The aim of the pilot projects would be to study and quantify the way in which changes to the urban landscape could affect stormwater detention, infiltration and evapo-transpiration as alternatives to disposing of water through the drainage system.