From flood threat to urban opportunity

In this extract from a new book, Aquatecture, its authors examine how to make water work rather than threaten cities

At a city scale, the inter-relationship of different parts of our infrastructure becomes crucial to continuity of services, from power to flood defences. Breakdowns to any one service can significantly affect many people and businesses. 

Take New Orleans. Hurricane Katrina and the failure of the levee caused an almost total evacuation of the city, flooded approximately 80% and generated an estimated US$17 billion in damages. Faced with Hurricane Gustav three years later the mayor ­decided to evacuate the city to avoid a similar catastrophe. This too carried a significant cost to the economy, though in the end the hurricane only causing limited flooding. 

This shows how major infrastructure projects have a lasting effect on a city, powerfully influencing its opportunity for growth or evolution. The need for them to operate in potentially different climatic conditions has to be factored into the design. More unexpectedly, infrastructure as a whole can provide multiple benefits – such as green and blue corridors as conduits for other services, energy and transport. Neighbourhood energy hubs can be connected to each other or to a city heating system, as well as provide safe havens from flooding. Flood defences may be required around older, high-density, or historic parts of the city, but these could also be public spaces.


 

Water music

For the last 70 years the shallows of Lake Constance have been transformed biannually for the Bregenz Festival ‘Opera on the Lake’. The modern all-weather platform is fixed to piles driven into the lake bed, but the original floating stage was built on top moored two barges. The extraordinary sets and beautiful setting are great example of water placemaking and attract visitors from around the world.


 

Energy

A distributed energy network has the potential to improve resilience in the event of failures or disasters. This can work well with neighbourhood or district energy centres, allowing them to supply power back to a larger grid/network, particularly when there is a range of renewables generating power at different times – as with the dedicated local energy centre at the 2012 London Olympics. Achieving zero-carbon through on-site renewable power alone can be difficult for cities because they need so much energy. As a result regional energy centres located outside the city are likely to be necessary.

Flood defences

City-scale flood-risk management requires many different measures, involving planning, resilience, attenuation, relief channels, and protection. Continuity of flood defences must be considered: first, to ensure that standards of protection are consistent; and secondly, to avoid weak points that, if breached, could compromise the integrity of the whole system. When set back from the river edge, defences can be integrated within the city plan, public space, parks and road network, rather than canalising the river. This can be cheaper and improve quality when combined with other infrastructure. Where defences are required, better design can improve their integration within the environment and maintain access to the water. In Spain, OAB Architects worked on the designs for Benidorm’s sea walls and promenade to create a colourful, undulating sculptural wall. Also in Spain, Basque artist Augustin Ibarrola playfully decorated the concrete sea defences in Llanes, a fishing village in Asturias. Elsewhere, integrating sea defences with steps and seating in the public realm has made them less discernible. And they needn’t be visible at all. The world’s largest underground flood storage facility was created in 2009 in Greater Tokyo to alleviate flooding during typhoons. When the river level reaches its peak, water is channelled into five silos before being pumped through tunnels and discharged into an adjacent river. The silos are 25.4m high and 177m long, and connected via 6.5km of tunnels.

Wastewater

Waste treatment facilities are typically built outside urban areas and treat waste from several settlements. Decentralised waste treatment reduces dependence on centralised systems as it is often difficult to find space for waste treatment in cities, particularly in high-value central locations. Sustainable drainage can help to reduce the capacity required in wastewater treatment plants by removing surface water from foul drains. The city of Shenzhen in China has built the world’s largest integrated two-stage wetland to clean the Longgang River, which carries the unfiltered effluent of 20,000 inhabitants and their industries. The wetland, with a 20,000m2 surface area and a cleaning capacity of 5,000 to 7,000 tonnes per day, began operating in 2001.


 

Island ideas

A €365m new flood-relief channel and dyke has been built in The Netherlands to reduce the risk of flooding and help support redevelopment of Lent. Eiland Veur Lent and Nijmegen is part of the national ‘Room for the River’ programme to deliver a series of measures to make space for water and reduce flood-risk. Baca provided landscape and development ideas for the island created by the new waterway. The proposals for an eco-tourism destination embrace the water/landscape with recreation, facilities and innovative flood-proof buildings set on the waterfront. Construction on the flood relief channel began in 2013 and is due for completion this year.


 

Transport

Efficient and interconnected mass transport systems are better for all settlements: high-density and compact or low-density and distributed. Although water can be an obstacle to movement, it may also be used for transport. Water buses operate in many major cities – such as the Thames Clipper in London, the Himiko in Tokyo, the Rotterdam water bus, and the Batobus in Paris. Bangkok, Venice, Chicago, Sydney and New York all have water taxi services. City-scale bridges can help connect districts and allow expansion into other areas. The experience of arrival, crossing and departure is an opportunity for architectural elaboration and place-making. Pulteney Bridge in Bath replaced a ferry crossing over the River Avon in 1774; shops built on both sides of the bridge seamlessly link with properties either side of the river. Once a common sight, these shop-filled bridges have become unique attractions. In 2003 a new crossing called The Murinsel, by architect Vito Acconci, was built on the River Mur in Graz, Austria, to reconnect the city with its river. At its centre, a floating island housing a café and terraces creates a moment in the journey and a mid-river meeting place – popular with locals and tourists. Urban watercourses are vital multi-functional conduits; they should be planned with other means of transport to work with them and complement the system as a whole. Interfaces between different transport hubs and routes are opportunities to create civic delight and assets for future generations.

Leisure infrastructure

During the 19th century there was much investment in the construction of pleasure piers. The St Pauli Piers (1839), also known as the St Pauli Landing Stages or Bridges, are the largest landing place in the Port of Hamburg and a major tourist attraction. Brighton Pier in the UK has welcomed visitors since 1891; Chelsea Piers, New York, followed in 1910.

These large structures required substantial engineering works and are an example of public and private investment in primarily leisure-specific infrastructure. Piers may extend far out from the land to find deeper water for sea-going vessels and allow tides and currents to flow unhindered beneath them. They offer a combination of accessible public space, fee-paying entertainment and fairgrounds for thrill‑seekers, and wonderful panoramic views. Bregenz’s Festival on the Lake pavilion performs a similar function.

Working with water at infrastructure level is exciting both for design, city engagement and the future resilience of our cities. We like to be near water, so architecture’s mantra should be to make it work for the city. 


 

A powerful statement

A hydroelectric power station along the River Iller in Kempten, Germany supplies 10.5 million kWh of renewable energy a year to approximately 3000 households. The sculptural forms, designed by Becker Architects, evoke the power of water, with a likenesses to glacial structures carved away by melt water. The aesthetic of this power station helps to create a local landmark building that is equally functional in water management and energy generation.