The paving and asphalt has been replaced by a raingarden, cutting the amount of rain that flows into sewers. Derbyshire Street, East London. Greysmith Associates

We are failing as a city to develop in a co-ordinated way, intelligently integrating our infrastructure by using plants and porous surfaces to slow down the torrents of rain we instead funnel into our drains and rivers.

The All Party Group for Excellence in the Built Environment is right when it says that there is no effective leadership for water management but instead a damaging blend of confused policy and missed opportunity.

It is clear we don’t have an intelligent approach to green infrastructure in London. Green spaces amounting to 22 times the size of Hyde Park have been paved over in a generation. Yet too little has been done to tackle this. The law passed in 2008 to make sure paving used on front gardens lets through water is rarely enforced. It’s an empty gesture. So flood risk increases and rivers suffer.

We need these expanses of hard surfaces broken-up with more plants, watered by rain. Streets that not only benefit rivers but cut air pollution and urban heat islands – that make London a better place to live. These will be human-friendly and river-kind.

Over the next 20 years New York City will spend almost £1 billion on river-friendly drainage to cut the amount of rain that overwhelms its sewers and pollutes its waterbodies. This is in addition to investing £2 billion in conventional grey infrastructure to cut sewage spills into rivers. The two approaches are linked and synchronised. Their approach is very different to London’s – weaving nature into New York which “beautifies City streets and neighborhoods while improving air and water quality“. These raingardens and green roofs are already being created, instantly reducing the burden on the sewer system. New York City estimates that if it was to only use conventional or grey infrastructure it would cost £4.4 billion.

Bio-swale, New York City, Demo Area 2. Photo courtesy of NYC Water

As the former Mayor of New York said in 2010 “To succeed, any plan must be effective and affordable, and the 8.4 million New Yorkers who will pay for it must see and feel its benefits. The NYC Green Infrastructure Plan will achieve that goal. Based on years of study and our experience with new technologies, we know that green infrastructure—advanced street-tree pits, porous pavements and streets, green and blue roofs, and many other stormwater controls—can improve water and air quality, help to cool the City, reduce energy bills and greenhouse gas emissions, increase property values, and beautify our communities. And we can achieve all of these benefits for billions of dollars less than the cost of the traditional tanks and tunnels that are useful only when it rains.”

London must learn from New York City’s Green Infrastructure Plan and develop one that includes all of the capital, not just the centre.

London Waterkeeper wants to see a single, comprehensive strategic approach developed that co-ordinates the disparate councils, companies and bodies. This Commission would lead and direct a long-term plan that harnesses the strengths of both green infrastructure and conventional drainage as New York is doing. Again, as the All Party Group says, green infrastructure and sustainable drainage are ”…a key part of water management strategy…” but “There needs to be a definitive and clear arrangement that compels the major stakeholders to co-operate.”

Links:

All Party Group for Excellence in the Built Environment report – Living with water

Derbyshire Pocket Park – uses natural drainage systems to cut the amount of rain that enters the local sewers. If scaled up across London these could hold 10x the amount of rain than the Thames Tideway Tunnel

Designers of Dersbyshire Pocket Park – Greysmith Associates

New York City Green Infrastructure Program

London Infrastructure Plan 2050

Sustainable Drainage Systems (SuDS) Sudsdrain website

Depave

Portland, Oregon. Grey and green infrastructure, co-ordinated plan

Guidance on the permeable surfacing of front gardens. The 2008 changes.

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