Fresh water is an essential but limited resource

Water is essential for all life on Earth. It covers approximately 71% of the earth’s surface yet only 3% is fresh surface groundwater. Of that small percentage more than half is locked up in glaciers and ice caps. This leaves only 0.75% freshwater that is potentially available to sustain the global population with drinking water, meet its irrigation needs and supply water for industry and energy production purposes (USGS, 2019) ^[1].

In addition, this water also needs to be sufficiently available to the environment, plants and animals – today and for all generations to come.

A further decrease in freshwater availability comes from climate change and other human-induced pressures. (PBL, 2019) ^[2]. Also in Europe, water scarcity is becoming a widespread and increasingly frequent phenomenon, as local water needs often exceed available water resources ^[3]. According to the European Environment Agency (EEA) (2021) ^[4], 20% of European territory is affected by water stress during an average year – a situation in which there is insufficient water quantity or quality to meet the demands of the environment, society and economy. 

In Belgium too, we are not immune from water scarcity: ranked 23^rd out of 164 countries in terms of water stress exposure by the World Resource Institute (WRI) (2019), making the country the third highest water-stressed state in Europe, after Cyprus and San Marino ^{[5] [6]}. For our region, climate change is leading to both an increase in drought and an increase in peak floods. Belgium, and especially Flanders, has a high population density, a considerable number of built-up localities and an extensive paved surface area, making it one of the most urbanized regions in Europe ^{[7] [8]}. We are facing an increasing risk and frequency of fatal floods and dry summers ^[9].

The challenges we face are twofold: due to an increase in drought conditions, we experience more water stress, and due to increased peak rainfall, we suffer from more flooding. These two effects are becoming more frequent and more intense.

There is a very real risk that difficult choices will have to be made about who can use how much water and for what purposes. Access to fresh water will not be available to every user (transport, agriculture, energy, industry, households and environment) at all times and without limitation. We have seen how flood damage quickly runs into billions of euro, in addition to the personal tragedies of the people affected.

Climate change is without doubt and by far the most important main driving factor for increasing drought and flooding. By analyzing the situation in our region, we conclude that our choices, in terms of infrastructure, were not always the best. Among some of them: watercourses were “straightened,” wetlands were drained and our sewage system served to drain away rainwater as quickly as possible. And above all, we have a very high degree of “soil hardening” in our densely populated region.

“Water has many users, each with their own social and economic interests. But that doesn't have to turn it into a competitive battle,” argues Inge Genné. “The same drop of water can be reused many times. But for that, we'll need to make our water usage smarter and encourage reuse. And that can only happen if users get to know one another better and discover each other's water needs. That's how we can set up collaborations and even bring about some win-win situations.” (source)

Sustainable water management refers to the use of water in a way that meets the economic, social and environmental needs of the present, without compromising the ability of future generations to meet their own needs. Sustainable water management requires maintaining a balance between the supply and demand side of water resources, ensuring that water consumption levels never exceed renewable water availability.

Sustainable water management is feasible in different domains and at different levels and can be undertaken by all types of users. Furthermore, if we are wise with our public infrastructure, the environment will also play a helpful role in creating a solution.

There are many initiatives in Flanders that illustrate the diversity of possible solutions, applicable on a large and small scale: the greening and softening of the public domain, the restoration of wetlands, active infiltration, the use of rainwater, circular water use, smart metering systems, water scans and many other innovative solutions. It should be emphasized that solutions are best achieved through collaboration between stakeholders and their systems. No single stakeholder can address the problems alone.

Overarching strategies need to be established and rolled out to address the inter-connected water challenges. Important public entities in this context include national, regional and local policy makers, environmental and watercourse authorities, drinking water and wastewater companies, etc. to implement sustainable water management plans. These water management strategies can address both the supply and the demand side of the water equation to ensure a balance between the available water resources and the increasing consumption levels.

A number of key economic actors and water users such as agriculture, industry and energy production can also play an important part of the solution. In addition, households can significantly contribute by sustainably managing their water use and rain- and wastewater streams.

With a view to climate adaptation, for the overall water system to sustainably increase water availability and help absorb the impact of heavy rainfall, the "Ladder of Lansink," applied to rainwater provides useful insights into an order of preference for how rainwater should be handled.

Ideally, stormwater runoff should be avoided. For example, by limiting paving and drainage as much as possible to allow water to infiltrate on site. As a next step, rainwater can be collected and used for irrigation or for various purposes, after proper treatment. Also, maximum infiltration is fundamental, for example by installing wadis, infiltration facilities and green areas.

If water cannot be reused or infiltrated locally, the accelerated discharge of rainwater should be avoided by buffering and delayed discharge. Finally, it is preferable for the runoff to go through a separate system, if available, rather than a mixed system where rainwater and wastewater come together.