Slow water: can we tame urban floods by going with the flow?  As we face increased flooding, China’s sponge cities are taking a new course. But can they steer the country away from concrete megadams? Guardian Erica Gies  Tue 7 Jun 2022  After epic floods in India, South Africa, Germany, New York and Canada killed hundreds in the past year, droughts are now parching landscapes and wilting crops across the western US, the Horn of Africa and Iraq. The responses have included calls for higher levees, bigger drains and longer aqueducts. But these concrete interventions aimed at controlling water are failing. Climate extremes are revealing a hard truth: our development choices – urban sprawl, industrial agriculture and even the concrete infrastructure designed to control water – are exacerbating our problems. Because sooner or later, water always wins. Water might seem malleable and cooperative, willing to flow where we direct it. But as human development expands and the climate changes, water is increasingly swamping cities or dropping to unreachable depths below farms, often making life precarious. Signs of water’s persistence abound. Supposedly vanquished waterways pop up in inconvenient places. Seasonal creeks emerging in basements are evidence that those houses encroach on buried streams, while homes built on wetlands are the first to flood.

When our attempts at control fail, we are reminded that water has its own agenda. Water finds its chosen path through a landscape, moulding it and being directed by it in turn. To reduce the impact of today’s more frequent and severe droughts and floods, a new global cohort of “water detectives” – restoration ecologists, hydrogeologists, biologists, anthropologists, urban planners, landscape architects and engineers – are asking a critical question: what does water want? Figuring out what water wants – and accommodating those desires within our human landscapes – is now a crucial survival strategy. The water detectives start by uncovering what water did before generations of humans so radically transformed our landscapes and waterways. How did water interact with local rocks, soils, ecosystems and climates before we scrambled them? As those detectives make more discoveries, we can begin to understand why certain areas flood repeatedly, or how our tendency to speed water off the land deprives us of urgently needed local rainfall. Then we can start to think creatively about how to solve these problems, by making space for water within our existing habitats.

The answers that the detectives are finding – in cities, fields, swamps, marshes, floodplains, mountains and forests – are that we should be conserving or repairing natural systems, or mimicking nature to restore some natural functions – and not building more concrete infrastructure. These reparative approaches go by various names: nature-based systems, green infrastructure, low-impact development, water-sensitive urban design. In China, the “sponge cities” initiative aims to make urban regions better able to absorb rainfall and release it when needed. Because these kinds of solutions are based on working with or simulating natural systems, they offer benefits beyond just reducing floods and droughts. They can help us address the dramatic declines of animal species. They can help us adapt to climate change, or even slow its progression. Protecting biodiversity and storing carbon dioxide are not just peripheral effects of solving water problems – they are integral to healthy natural systems. 

So what does water want? In its liquid state, with sufficient quantity or gravity, water can rush across the land in torrential rivers or tumble in awe-inspiring waterfalls. But it is also inclined to linger to a degree that might surprise many of us, because the infrastructure of the modern world has erased so many of water’s slow phases, instead confining it, containing it, or speeding it away. These slow stages are particularly vulnerable to human interference, because they tend to occur in flatter places – once floodplains and wetlands – that we blocked or drained so that we could settle. But when water slows and stalls on land, that’s when the magic happens, providing habitat and food for many forms of life above and below. The key to greater resilience, say the water detectives, is to find ways to let water be water, to reclaim space for it to interact with the land. Innovative water management projects aim to slow water on land in some approximation of natural patterns. For that reason, I’ve come to think of this movement as “Slow Water”. Like the Slow Food movement – founded in Italy in the late 20th century, in opposition to fast food and all its ills – Slow Water approaches are bespoke: they work with local landscapes, climates and cultures rather than try to control or change them.....read on         https://www.theguardian.com/environment/2022/jun/07/slow-water-urban-floods-drought-china-sponge-cities