Sustainable Urban Water
From the most ancient civilizations to today’s modern cities, water has been a key element enabling human civilization to grow, prosper and flourish. The central role of water in the development of cities cannot be overstated. Throughout history urban water infrastructure has strived to provide health through adequate water supply and sanitation, safety from floods, and well-being for citizens through parks, fountains and healthy waterways and ecosystems.
However, over the last few decades, rapid urbanization coupled with climate change has presented new challenges. Cities are growing at an unprecedented rate, over 200,000 new inhabitants settle in cities around the world every day! This new challenge requires us to plan our water infrastructures differently. In addition to health, flood safety, and well-being, we need our water services to be regenerative.
The high number of people concentrated in relatively small geographic areas requires us to be more creative about how we use and protect our natural resources; and how we reuse them so that we minimize the required inputs to our cities in terms of flows of water as well as other materials and wastes. In addition, climate change is impacting how we evaluate water-related risks in terms of flooding or future available freshwater resources. The need to plan around uncertain future resources requires many cities to evolve towards systems that minimize the inputs, even for cities without rapid population growth.
Just like many ecosystems on earth, we are transitioning to being an urban “mature ecosystem”, where all wastes are reused and dependencies are minimal. Our urban metabolism needs to evolve to provide these necessary characteristics of resilience. To achieve this new balance, we need to foster principles and policies that create virtuous loops, so that our cities move towards circular systems. We need our water services to become “regenerative”, so that they protect the quality and quantity of water resources for future generations and are efficient in their use and production of energy and materials. Regenerative water services apply the 5 Rs principles: Reduce the amounts used; Reuse the water for different usages with fit for purpose quality; Recycle or “upcycle” materials such as nutrients or organic matter; Recover the energy whether it is heat, organic energy from used water, or hydraulic energy; and last but not least Replenish the surrounding environment by discharging only small amounts that can be eliminated or absorbed by the natural environment.
Beyond the regenerative aspects of a mature urban ecosystem, we can further learn from natural ecosystems in the way rainwater is absorbed in a sponge-like manner by the forests and soils to be slowly released for use by the ecosystems. Similarly, our cities can increase their flood protection and resources in freshwater by mimicking these natural systems, with rain water storage and slow release through green and/or grey infrastruture such as parks, bioswales and wetlands, and/or actual storage tanks.
I invite you to read the Chapter 10 of the SWWW report and to come and contribute to the urban workshops at the IWA Water Development Congress and Exhibition in Jordan, where the Urban Water Charter draft will be discussed.