By Kristina Hill*
Suppose you woke up to discover a deep disturbance to the space/time continuum. Authorities have given 20 to 30 years before relocating you, and billions more, to a very different planet. The new habitat is hostile to how contemporary cities function, but you have no choice. Everyone must go.
Science fiction? Dream on. Scientists have demonstrated that humanity is living its last stable decades of an 8,000-10,000-year climatic era, after which global water distribution will slip, seasonally and geographically, into radical disequilibrium.
This calls for a new thinking, and action. Waterworks have been described as arteries and veins, a kind of urban metabolism. But looking ahead, we’re not talking about tweaking blood pressure here, avoiding clots there, or even performing an intricate high-level bypass surgery. We’re talking about amputating entire chunks of our circulatory systems, grafting on new organs, re-organising the internal connectivity of vessels along with where and how those systems pulse. Change must happen without anesthesia, on the cheap, while systems live, breathe and function.
No city is immune. High above, melting glaciers and diminished snowpack will reduce mountain runoff.
Down below, sewage treatment plants will increasingly confront fresh- and saltwater flooding. Formerly reliable wells will dry up or grow saline. Rising sea levels will all too often overwhelm flood control channels. Tidal gates– which proliferate to protect coastal cities–will exacerbate water quality and flooding problems as even tributaries can’t release currents into the sea.
Initially, water systems may cope. Cities can recover from stressful setbacks, the water system equivalent of a 24-hour fever or flu. But at some point the condition turns chronic.
Entire sections of cities are likely to suffer from frequent–eventually, permanent–inundation.
Much as emergency room visits overwhelm healthcare budgets, urban water professionals–faced with extreme spikes in drought and deluge–are engaging in broad new conversations, asking hard questions about limited funding sources and structural reforms. In the best cases, fresh answers will emerge, as people imagine truly innovative design and management strategies.
To shape this process of radical change, urban water system planners and engineers can start by looking hard not just at our urban waterworks, but also the surrounding natural infrastructure of which cities are part: our landscapes.
Exciting new programmes for dealing with extreme flooding use landscapes to hold water back, before and during all stages of water conveyance. In the Pacific Northwest of the 1990s and 2000s, Seattle and Portland led a movement to develop landscapes that improve functionality and capacity of urban water systems. Others soon followed, in contexts ranging from a watershed on the University of Virginia campus, to water-plazas in an urban district in Rotterdam.
The triad of stormwater, water quality and fish habitat produced novel approaches that have been embraced from Sustainable Urban Drainage Systems (SUDS) in Berlin, to wetland parks in China, and from Stockholm urban stormwater architecture in the Hammarby-Sjöstad district, to new studies of green infrastructure in Johannesburg. Such innovations showed us how to design and manage the capillaries and veins of our urban systems for multiple gains in health, stormwater capacity, and the urban metabolism.
Yet the climate keeps changing, putting unimaginable stresses on water systems, on inflow supplies, and on outflow sewage conveyance and treatment. We know we will have a lot less water to start with. But volatile precipitation also means we can store even less of that rain in our current reservoir strategies. Some cities face a choice: surround big sewage plants with medieval walls, or abandon them in favour of smaller, distributed facilities within developed districts.
Outside of Washington DC, no leaders ask whether extreme shocks will come–as sea levels rise at least 10 feet, and temperatures go up a degree or more–but where, when and how severely they will impact existing water systems.
Again, understanding landscapes is the “first principle,” the starting point for innovations. Where will the new shorelines be? How much wave energy will we face? How often will storm surges come? What rock and soil substrates will groundwater have to move through?
Such questions may at first feel odd, hard, extreme. But only by asking can we can find innovative answers. Only then can we think of water systems as buffers, or “micro-polders” that help us adapt to coastal and inland surges, while using supplies with more care and value. Only then can we experiment with new approaches that link cities with their landscapes.
Progressive cities line sewage and storm drains with new pipes. California vineyards help recharge groundwater in wet years. Hampton Roads, Virginia, is studying injection of treated sewage effluent into deep aquifers to repel saltwater intrusion. Phoenix, Arizona’s water storage and recycling systems provide a dryland case study in regional innovation. Hamburg’s Hafencity district on the Elbe River pioneers “floodable development,” complete with waterproofed first floors. New Orleans’ 2013 Water Management Strategy and Rotterdam’s Water Plan 2.0 demonstrate integrated strategies for cities where rivers meet the sea.
These examples arose not when people denied the near end of a 10,000- year era of stability but because they awoke. They decided to think and act. They chose to invest in experiments and creative designs. They tapped human ingenuity, integrating urban metabolism into living landscapes in ways that might, just might, help us adapt and inhabit that radically new planet.