There are many factors that are upsetting the balance between water use and supply around the world. Not surprisingly, most of them are the result of human activities. The impacts of climate change and environmental degradation are undeniable. Many places also suffer from a lack of resources, capacity and poor infrastructure. And in other places there is a growing sense of entitlement about access to water, which can lead to inefficient use without concern for supply issues. All of these things are putting a strain on existing water resources.
But arguably one of the biggest factors contributing to the rising demand and competition for water is the swelling global population. Now at 7.6 billion, the world population is expected to reach 8.6 billion by 2030 and 9.8 billion by 2050. According to the UN, 55% of the world’s current population lives in urban areas, and that is expected to increase to 68% by 2050. Their projections show that urbanisation, a shift of people from rural to urban areas, combined with the overall growth of the world’s population, could add another 2.5 billion people to urban areas by 2050, with around 90% of this increase taking place in Asia and Africa.
Cities on the brink
So urbanisation is bringing cities to the forefront of the fight against water scarcity. Perhaps the most publicised recent example of a city facing a water crisis is Cape Town. With record drought, population growth and climate change, reservoirs are perilously low and the city is scrambling to find new sources of water. Thanks to recent rains and stringent consumption restrictions, Cape Town has managed to push ‘Day Zero’ - the day they shut off water taps to houses and businesses - out to 2019.
But it’s not just a concern for Cape Town. In fact, the list of major cities facing water scarcity issues around the world continues to grow. Places like Mexico City, Jakarta, Sao Paulo, and Beijing face increasing threats of severe drinking water shortages for various reasons. Many existing cities face the challenges of outdated supply and sewerage systems, while developing cities often face supply and sanitation issues. Bangalore, for example, loses more than half its drinking water due to an antiquated plumbing system and struggles with water pollution. And London, with an increasing population and ageing water infrastructure, is likely to have supply problems by 2025 and serious shortages by 2040.
A sense of urgency
Although 2040 may seem like plenty of time to find solutions, it’s not, according to IHE Delft’s Professor Guy Alaerts. Having worked in academia and with the World Bank, he says experience shows that building something like a big dam or major flood protection infrastructure, or changing consumption habits of people requires the time span of about 30 years. “If you want to do something about such a kind of tipping point, when the majority of the world population starts to be in precarious positions, then you have to start doing things now,” he says. “All of these big projects cost a lot of time. Knowledge and experience travels very slowly, changes minds very slowly.”
Typically, people don’t care too much about what is going to happen in the distant future, says Alaerts, and that includes the water sector. He also points out that taking action is not just for one particular discipline, it’s something that runs across all the groups in the Institute. “It has to do with integrated water management, water supply technologies, wastewater treatment, ecology, modelling, and weather forecasts,” he says. “Everybody should be part of the discussion.”
The case for Nature-Based Solutions
The UN World Water Development Report for 2018 proposes that to address the increasing challenge of water security, Nature-Based Solutions (NBS) will be key. NBS are what is referred to as “opportunities to harness the natural processes that regulate various elements of the water cycle”. They can range in scale from the micro/personal to landscape level applications, with some being more suitable for either urban or rural environments. It’s using the power of nature to help achieve the three main UN water management objectives – enhancing water availability, improving water quality and reducing water-related risks. And ultimately, they argue that NBS offer high potential to contribute to the achievement of most of the targets of SDG 6 for water.
But, despite an increase in the interest in NBS, water resource management remains largely dependent on human-built (‘grey’) infrastructure. The report states, “The idea is not necessarily to replace grey with green infrastructure, but to identify the most appropriate, cost-effective and sustainable balance between grey infrastructure and NBS considering multiple objectives and benefits.”
There are those who say that NBS are not feasible from a cost-perspective, but that is not necessarily the case. One example of a cost-effective NBS on a larger scale is the Amsterdam Dunes project. Needing to increase water supply, they decided to work with nature as opposed to expanding the existing treatment plant. The project involved pumping water to the dunes and using the dune sand to filter and treat the water, which now requires only a minor post-treatment process. The 35 km2 area, which has also been protected as a nature reserve, provides two thirds of the drinking water for the city of Amsterdam. “Not only does it cost less than the infrastructure project,” says Professor Alaerts, “but it’s more secure, has better taste, it’s more stable in terms of quality and you also have a nature park. It’s a fantastic win-win.”
A blue-green approach
One IHE Delft effort putting NBS into action is BEGIN, or Blue Green Infrastructure through Social Innovation. This Interreg NSR project aims to implement, develop and mainstream new methods of deploying nature-based solutions in an urban environment. Though the project focuses primarily on flooding in 10 cities across the North Sea region, IHE senior lecturer Berry Gersonius says it is also relevant to the issue of water supply. “The beauty of Blue Green infrastructure is it is mainly above-ground solutions which are mostly non-engineered, but more natural or nature based, so they mimic natural processes,” says Gersonius. “They provide flood protection, but at the same time they provide a whole lot of other benefits including water supply.”
A Blue Green infrastructure provides different services, some of which are called adaptation services. They can include climate change protection, flood protection, water supply, or purifying water for quality purposes. But, according to Gersonius, they also provide a whole range of other benefits like ecosystem services, opportunities for recreation, and they usually create an attractive and healthy living environment.
In addition to all of the benefits, there are some challenges. For example, how do you actually capture the benefits of NBS when they are often more small-scale solutions spread throughout a city? And Blue Green infrastructure can be more expensive to implement than the traditional grey solutions. But Gersonius thinks there is a bigger picture with grey vs Blue Green infrastructure. “Sometimes those solutions are cheaper to implement, but then when you compare the social cost benefit analysis you see that, overall, these Blue Green solutions provide a higher value to society,” he says.
Gersonius notes that there are a number of factors that can contribute to successfully implementing Blue Green infrastructure. Finding ways to monetize the benefits, making a business case, can help convince politicians to invest. In cities with fewer resources it may be easier to attract in-kind resources, like maintenance or implementation of solutions by the community itself. If you do lifecycle costing, considering a good design that’s easily accessible for maintenance and will not deteriorate too fast, it can be cheaper in the long term. Ultimately, also, connecting the different stakeholders and involving them in the design process ensures a combined effort that is tailored to the community.
Traditionally, urban water managers have relied on large-scale, supply-side infrastructure projects to meet increasing demands for water. And there clearly remains a need for effective management of existing water resources and infrastructure, as well as developing new sources, including groundwater, re-use and desalination. But another strategy with great potential is changing consumption habits.
According to Dr. Janez Susnik, a senior lecturer at IHE, activities like watering gardens, washing cars, flushing toilets, and some industrial applications constitute somewhere between 40 to 70% of all urban water demand. So he’s looking at other ways of sourcing water for purposes that don’t need to be drinking quality. The idea with alternative supplies is to use things like rainwater or treated wastewater for non-essential purposes. “You’ve got more supply options, and by diversifying your supply you’re increasing resilience to change and you’re reducing the pressure on traditional supplies,” he says.
It’s not necessarily a new idea. For example, in many places people use small tanks to harvest rainwater for the purpose of watering their gardens. “That’s 200 litres that you’re not using from the main water supply. That’s what I mean by reducing supply stress,” says Susnik. “It’s not new because a lot of people do it at the level of a household, but to do it on the scale of a city, we’re not quite there because of infrastructure issues and public acceptance issues as well.” But he argues that we need to get people to think this kind of change is possible.
Changing consumption habits will mean different things in different places. In a developed society you could, for example, incentivise people to take up water efficient technologies or collection methods by subsidising water efficient appliances. “Once such appliances are in the home, the water use reduction is automatic,” says Susnik. “But it’s also just a philosophical shift in how you do things.” In developing nations, he says, the focus is going to be on system improvements and reducing leaks, as well as strengthening the institutions so they’re more able to deal with the challenges.
IHE as part of the solution
Responding to the urban water crisis is obviously no small feat, but Professor Alaerts believes that IHE Delft can play a significant role in finding solutions. “I think it’s important that we start to think more about impact,” he says. But Alaerts believes it’s not enough to be academic and publish papers, it’s about making a more measurable impact on the ground. “As an institute, how can we become more effective in bringing all of these good ideas to the world? We know how to do it, and we can help to spread the message and develop the skills and capacities to do the right thing.”