Professor Čedo Maksimović, Imperial College, London, Faculty of Engineering, Department of Civil and Environmental Engineering

Of the remaining 2.5%, glaciers and snow account for 68.99%, groundwater 29.9%, soil moisture, swamps and permafrost a further 0.9% and only 0.3% is composed of rivers and lakes. The latter is our only renewable water resource. Of the entire quantity of water abstracted from nature (rivers, lakes and underground aquifers), agriculture uses 68%, the energy sector 10%, households and industry around 19%, while the remaining 3% evaporates from reservoirs and lakes.

You have spent years dealing with the issue of urban water – from water supply to floods. What is the situation like globally today when it comes to the sustainable and efficient use of water?

Due to water becoming increasingly polluted, the quantity of water that is economically viable for exploitation has reduced drastically. Bottled water is often sold for more than oil and its derivatives. Climate change causes even more chaos because the timetable of water availability is changing, such that now, more often than ever, we have too much water in certain periods (which causes floods, landslides etc.), and at other times we don’t have enough water (droughts, food scarcity).

Many parts of our planet are becoming increasingly uninhabitable, while some areas have already become completely deserted due to a lack of water. Wealthy countries are not exempt from this problem. A drastic water deficit has been felt in California and other southern U.S. states in the last few years. The entire world is now facing the need to seriously re-examine long-term water management strategies. Old rules cease to apply, as they crumble overnight.

What are the global priorities for preserving water resources that are on the verge of destruction due to excessive pollution?

It is very easy to say that we need to stop polluting our water resources (the same goes for air and soil), but this is quite difficult to do. After several decades of failed attempts to reach a global consensus on mitigating (or at least decelerating) the negative effects of climate change, a good initial breakthrough was made at the COP21 conference in Paris, so we can expect a similar breakthrough in the implementation of the UN’s Sustainable Development Goals (SDG), in which water resources play a major role. However, this shift needs to happen first and foremost in our minds, so that we can start ‘clearing’ our own ‘dump’ first, as it were. Nobody is spared from this ‘plague’.

Regardless of the country’s economic potential, investments should not stop, otherwise the consequences could be catastrophic. There needs to be a balance between construction of new anti-flood systems and good maintenance and reinforcement of the existing ones

You have coordinated projects at theEngineering and Physical Sciences Research Council (EPSRC) and UNESCO’s International Hydrological Programme in London and Europe. You have also engaged your vast experience in the area of integrated urban water management in the Blue-Green Dream project, which provides a new approach to preserving our planet. What is that project about?

That project is all about having an innovative approach to future urban planning development and revitalising existing urban segments, but it can be equally applied to suburban and rural areas, as well as to individual facilities and systems of all kinds (residential, industrial, commercial, healthcare, eco-systems, recreational etc.). Instead of planning to develop individual sectors (water, power, food, ecosystems, infrastructure), where experts are trying to do their ‘best’ in their own field (while making it difficult for others), the project’s (Blue Green Dream – BGD) methodology favours two types of interactions: multidisciplinary (experts working as a team); and multifunctional (multipurpose systems).

The project is based on reducing the negative effects of climate change. By focusing on coordination between urban water infrastructure and urban green areas, the project helps to overcome strategic challenges related to the development of sustainable urban systems that are transformed from the centralised power and water infrastructure into decentralised and better-integrated systems. This includes overcoming challenges in three specific areas:

• Urban planning: developing the market for planning tools and providing support with the aim of creating sustainable cities.
• Integration of the system and services, amplifying positive effects and their interaction: supporting transition towards better integrated urban systems; higher resource efficiency – connecting urban infrastructure systems to the environment in order to efficiently utilise available resources, including recycling.
• All of the aforementioned should be done in a way that the total costs (of system revitalisation, utilisation and maintenance, i.e. the whole life costs) are lower than the conventional ones.

The Blue-Green Project has been implemented in the urban planning segment in Zagreb, Paris and Singapore. What results did the project accomplish in terms of economic and social development and environmental protection?

In these initial projects, which we implemented with teams of my colleagues and associates, we have improved both the living and working conditions of people in these systems through the use of local natural resources. We have also reduced energy outgoings and other costs drastically.

Instead of the old principle of we are protecting nature/environment, which implied huge investments with an uncertain outcome, we use seemingly inverse principles – “we use nature to protect us”, while at the same time “we are protecting nature”. By so doing, we have significantly reduced the costs and create better (and more durable) solutions with clearly defined and quantified indicators of integral performances in these systems.

Europe is a region with the biggest urban population and further growth tendencies. How does this fact, combined with climate change, affect water supplies in large cities?

In accordance with the principles and solutions of the BGD project, supplying cities, not only with water, food, power and healthy environment (both indoors and outdoors) in the future, has to be based on integrated solutions with maximum use and recycling of local resources. Everything that is today considered waste will be a precious resource in the future. Let’s take, for instance, rainwater which has always been thought of as a by-product of bad weather.

Collecting rainwater from roofs and using it to flush toilets and for other ‘technical’ purposes will gradually become not only a novelty but a standard solution. The same goes for the so-called grey water which is actually bath and shower water. If we used these two resources (that are currently discarded) alone to flush our toilets, we would reduce the consumption of drinking water between 25% and 40 %, as well as reduce the consumption of energy needed to pump up the water. We would also reduce the risk of flooding.  There are over 1,000 companies in Germany that are engaged in these and similar activities (production, installation and maintenance of the relevant equipment).

In accordance with the principles and solutions of the BGD project, supplying cities, not only with water, food, power and healthy environment (both indoors and outdoors) in the future, has to be based on integrated solutions with maximum use and recycling of local resources. Everything that is today considered waste will be precious resource in the future

Similar principles will be applied to other resources – energy, food, and all types of waste including, for example, the warm (waste) air from air conditioning units. If we used vegetation to lower the temperature in our buildings, we would reduce (or completely eliminate) the need for air conditioning.

And when we bring all urban infrastructure systems together under one ‘roof’ (read blue-green paradigm) and form a team of experts that, so far, haven’t interacted much with experts from other fields, we create new solutions.

In terms of Serbia, the majority of existing water supply systems were built over 30 years ago. How familiar are you with this fact and what solutions can you provide?

Water systems that were built 30 and more years ago (there are quite a few systems in other countries that are even older) are not the problem. The main thing is the quality of their construction and maintenance. According to the data collated by my colleagues, in many cases, modern water supply systems are built worse than their predecessors. Recently, a several-kilometre-long segment of a brand new pipeline caved in before it even became operational.

Serbia suffered huge damage from floods in recent years, mainly because there wasn’t a proper infrastructure in place to stop the floods. What efficient solutions can you propose to solve this decades-long problem, considering Serbia’s economic potential?

Serbia was not the only country to sustain huge damage in recent floods. The same happened in Croatia and Bosnia-Herzegovina. One of the reasons for such heavy flooding was very persistent and heavy rainfall, as well as a lack of investments in the reconstruction of anti-flood systems and their inadequate maintenance.

Regardless of the country’s economic potential, investments should not stop, otherwise, the consequences could be catastrophic. There needs to be a balance between the construction of new anti-flood systems and good maintenance and reinforcement of the existing ones.

Also, we should bear in mind that apart from the usual (fluvial) floods, the so-called rain-related (pluvial) floods, i.e. floods that usually happen in cities due to excessive rainfall, can also cause a lot of damage. This damage could be minimised in the future through the systematic use of BlueGreen solutions.

Wastewaters in certain parts of Serbia, particularly in Vojvodina, are contagious and have stunted the economic growth of entire regions. They affect agriculture and tourism, as well as posing a threat to public health. How are such problems solved elsewhere in Europe and in the rest of the world?

We should identify the origin of these wastewaters in order to reduce pollution risk. Wastewaters from urban areas are usually collected in separation systems or mixed sewage systems and are filtered. The big problem in Serbia is that many cities (including Belgrade) don’t have wastewater filtering systems and those towns that do, their filtering systems are either obsolete, neglected or don’t function at all.

Also, another problem lies in the fact that modern systems are very classically designed, and they are inefficient because they are built-in line with outdated technology. We have very modern technologies today which are more efficient, more compact, produce less sludge, use less energy and don’t stink.

As far as I know, not a single system in Serbia is designed with this new technology. The prevailing systems here fall victim to financial and other arrangements and become obsolete even during the design phase. The methods developed by the BGD project and our partners/associates in the project implementation can offer much better and more affordable solutions. However, the chances to break into this old, fairly closed system are not that great.

Climate change causes even more chaos because the timetable of water availability is changing, such that now, more often than ever, we have too much water in certain periods (which causes floods, landslides etc.), and at other times we don’t have enough water (droughts, food scarcity)

Apart from urban raw sewage, which is discharged at known locations (the so-called point source pollution), more and more is revealed about possible pollution coming from other (so-called diffused) sources. These are mainly wastewaters from farms and agricultural land, which is heavily fertilised and where runoff water is not controlled. Additionally, pollution can come from gutter flow in urban areas and roads. This type of pollution can be drastically reduced through the systematic use of BG solutions.

Over 30% of water is lost on its way from water plants to end consumers in Serbia. In European countries, these losses are under 20%. Considering that Serbia is rich with water resources, how valuable would you say this resource is going to be in the world in the near future?

It is a great misconception to think that Serbia is rich with water resources despite having two great rivers – the Danube and the Sava – running through it. Most of the territory of Serbia is exceptionally dry, especially when there have been long periods without rainfall.

In Europe, these losses range from a couple of percentage points to over 20% in old systems like the one in London. Reducing losses to a level that is economically viable is one of the main tasks of all water companies. With the implementation of other demand management measures, reducing losses is one of the most important measures for unconventional resources.

What economic benefits can Serbia gain if it manages to preserve its water potential?

So far, Serbia has been very flippant (by not applying pollution control measures) about these precious resources. The example of this is the degradation of the water quality in man-made reservoirs on the Danube-Tisza-Danube channel. This already has negative economic and health consequences. Conserving the water potential with conceivable economic benefits is primarily about completing the production of water reservoirs, in addition to preserving and improving the quality of water.

Serbia is considered an emerging country. What kind of synergy would be crucial for the sustainable management of the large water potential that we possess?

The key strategy here is wise management of water resources which, first and foremost, means collecting water during periods of heavy rainfall and using it rationally when rainfall is scarce. Due to climate change, the latter periods could be quite frequent and could have catastrophic consequences if water resources are not managed wisely.