By Tatiana Gallego-Lizon*
Urbanisation has transformed Asia’s economies. But it has also generated environmental degradation and a rising demand for resources. Now comes the volatile flux of climate change, complicating life for city dwellers while escalating pressure on their water-related infrastructure.
Water planning requires security, reliability, and fair access. Adaptive capacity builds on strategies that minimise disruption of the water cycle, improve efficacy, and enable the long-term availability of quality resources. To absorb compound stresses, the Asian Development Bank (ADB) has developed an urban climate change resilience framework.
The framework promotes flexible solutions that are not only robust, but anticipate potential failures. It integrates diverse perspectives of stakeholders in inclusive ways that become mutually supportive, and encourages deliberate redundancy. Far from theoretical, it draws on our real experience with water infrastructure in Asian cities over time. The result offers vital lessons on boosting resilience.
First, widen the circle of stakeholders to ensure integrated water planning. To preserve renewable water resources, include all institutions that share a watershed. Doing so builds support, boosts community self-reliance, and leverages local resources and knowledge. Through catchment models, holistic planners can track flows and transform stormwater runoff, treated effluent, and rainwater into a resource.
One step towards integrating water plans is to blend “blue” with “green” infrastructure. Green spaces help filter freshwater, recharge groundwater, ease run-off, manage floods, and reduce erosion. Whether preserving existing landscapes or investing in new projects–bioretention ponds, rain gardens, green rooftops, or bioswales–an adaptive city builds on the local environment, and mimics nature’s processes.
Engineers and economists seek efficiency but resilience demands back- up plans. Rather than rely on a single supply–reservoir, aquifer, rainwater, desalination, recycling–cities should diversify the water sources they depend on. Diverse sources help water managers adjust to flux in water quality and quantity caused by altered precipitation patterns, rising sea levels, and storm surges. A wider range of options help sustain extraction rates, minimise risks of saline intrusion and subsidence, and cope with increased turbidity and/or sedimentation.
To manage this more diverse menu of options and responses, resilient cities invest in strategic and flexible networks. Water infrastructure systems must be able to withstand and operate under emergency conditions, while also achieving flexibility through, say, strategic valves. Designs should also incorporate decentralised networks, which harmonise flows when adding new supply sources to an urban catchment.
Often the best new supply is simply to manage old demand. While many in Asia still lack access to piped water, affluence among those who do is already leading to excessive and unnecessary consumption. To reduce waste, resilient cities install meters throughout the system. They apply progressive volumetric tariffs, and adopt policies that conserve water in the built environment through, for instance, low-consumption fittings.
Ultimately, a city can’t adapt to climate change unless it also tackles its root cause. So the resilient ones reduce their carbon footprint. Less demand for water translates into less energy, and fewer chemicals, and greenhouse gas emissions. Efficient treatment can both decrease energy consumption and allow for co-generation from anaerobic digestion.
These seeds of resilience have taken root in some Asian cities. Now they must grow fast and replicate quickly. Singapore remains a leader in management, innovation, and source diversity. Jaipur’s Delawas sewage treatment plant is reducing its environmental impact. Mandalay’s future facilities integrate cogeneration systems that transform biogas into electricity.
Adaptation strategies can be custom designed. Consider the eco-city development approach pursued by the ancient city of Hoi An, Vietnam. It is simultaneously improving stormwater and water supply management, increasing lakes’ retention capacities, protecting reservoirs from salinity intrusion, and introducing early warning systems and evacuation routes.
Today most of the world lives in cities. Climate change is already altering the global hydrological cycle. In response, urban water security demands ever more resilient policy frameworks, which accelerate technology innovation, boost research and development, and support smaller cities and water service providers. All this may seem difficult, until you consider the alternative.