Floods. It seems no matter where you turn these days, you can’t escape news of flooding in some part of the world.
With a “monster” El Nino in full effect, it’s tempting to pass off this year’s soggy weather as a fluke, a one-in-100-year phenomenon. But as the climate continues to warm, “flukes” like this year’s string of floods will become more commonplace.
In December 2015, 200 nations gathered in Paris for COP21 to commit to keeping climate change in check. Even if we abide by the COP21 decision to limit global warming to 2° above pre-industrial levels, or its more ambitious target of 1.5° warming, we can still expect to see changes in climate systems, particularly when it comes to precipitation.
Mekong towns and cities, some of the most rapidly developing regions on the planet, face a number of choices as they build in the midst of these changes. Warnings that we have “one generation to save our cities” only hasten the need to make sustainable infrastructure decisions.
Traditional grey infrastructure such as concrete drainage canals, hardened river embankments, dredged and paved wetlands, are seen as the safe and reliable development options – perhaps the only development options – when building in an urban setting. And it’s no wonder as to why. By convention, grey infrastructure is development. It’s tested and fundable. Leaving natural systems in place is not development. From all over the world, the models we look to for inspiration depend on concrete-based development as the benchmark of progress.
But those models are showing their weakness, and it’s water that’s flowing through the cracks.
If Mekong cities and towns are to develop sustainably, if we are to embed climate resilience into our infrastructure and into our planning practices, we will have to work with nature rather than against it. We need to redress the imbalance underlying development assumptions. We need a natural based affirmative action.
Green infrastructure, or nature-based approaches, is a supplement, and in some cases an alternative, to traditional building techniques. It involves the greening of conventional infrastructure as well as the expansion of networks of natural and semi-natural areas within urban areas. It changes the way urban infrastructure – roads, drains, flood gates, river banks, water and sanitation facilities, electricity supply, and buildings – are conceived of, designed, and managed to be sustainable and resilient to the impacts of climate change.
Intense rain bursts common in the Mekong region’s wet season can cause short-term flooding. Simple techniques like permeable paving and storm water tree pits can mitigate these impacts by allowing water to infiltrate rather than running off and pooling. They can also serve a dual purpose by recharging groundwater.
Larger techniques, like natural drainage corridors and bioswales, require more intense planning. Current drainage trends rely on narrow, hardened canals to move water from area to another. Natural drainage and bioswales require that we rethink how water flows through an urban setting, incorporating and connecting these corridors as legitimate and necessary land uses. Natural slope stabilization techniques can brace banks and reintroduce habitat for fish and wildlife.
The recent flooding in Chennai in southern India stands out as a vivid example of what happens when natural drainage is ignored, hardened, and built upon. The city, built on top of numerous lakes and creeks, experienced the kind of incredible rain event we should expect to see more of as the climate warms. Years of unplanned development and encroachments poured concrete and solid waste into wetlands and canals that could have mitigated the disaster. Chennai is typical of conventional urban development worldwide – and a special concern in Asia where urban expansion is exponential.
A small town in drenched northern England bucked the trend and worked with nature to prevent its being flooded like its neighbours. Using nature-based solutions like log dams, heather bushels, and reforestation, the town of Pickering managed to slow upstream flows to a level the city’s traditional drainage could manage.
The International Centre for Environmental Management (ICEM) has worked with towns in the Mekong to assess climate vulnerabilities and to design adaptation plans that incorporate green infrastructure to increase their resilience to climate impacts. Towns like Dong Ha in Vietnam, Battambang in Cambodia, and Kaysone in Lao PDR gathered city planners, government representatives, and community members together to overhaul how they understand and build infrastructure in an uncertain climate. Cross-border workshops and hands-on design sessions sowed the seeds for a new way of developing. Their stories – and the techniques they used – are gathered in ICEM’s Resilience Resource Kit.
But to get the most out of green infrastructure, we must work fast. Nature-based solutions strengthen with time; the faster they’re implemented the sooner they become robust. Implementing strategies that work with nature will require an investment of money, training, and time, and Mother Nature doesn’t look like she’s interested in waiting for us to come on board.
Do you think nature-based solutions can help mitigate climate and other impacts? Do you have examples to share of times they've worked? Or even failed?