NCWR - Non Conventional Water Resources

In a nutshell

In this activity we ‘explore’ the urban water cycle and we learn what sustainable water management within a city is all about.

45 minutes

12-13 years old

In the field

Our objectives

In this activity you will:

Find out how the human activities impact the water cycle.
Discover how the water cycle works in an urban environment.
Be informed about the practices of sustainable water management.
Be motivated to consume water responsibly.

Things to use

Notebooks and pens, photo camera (or a cell phone to take photos)

Water-readings

Three water systems in a city

The water cycle “operates” differently in a city than in natural environment. The large amount of sealed surfaces (e.g. streets, highways, pavements, buildings, etc.) block the rainwater from being absorbed, reducing and enrichment of the groundwaters. Due to lack of wise urban planning, the natural river beds are often build, so the risk of floods in these areas further increases. In an urban environment the water supply network generates ““, while the sewage system and the rainwater drainage system generate .

In order to study the water cycle in a city, one may start by measuring the average in the drainage basin surrounding the city. The rain received is either absorbed by the ground or flows to the rivers and lakes, eventually reaching the sea. To ensure that this water is not wasted to the sea, an option is to retain it in stepped terraces on hills or collect it in reservoirs. After being collected, water is treated and distributed through an underground pipeline network , the . In this way, high quality potable water reaches our homes, offices, shops, etc.

The water supply system is fed by the available freshwater resources of the region i.e. lake, reservoir/dam, river, precipitation, springs and groundwater. However, many arid areas, such as the Mediterranean islands, rely on seawater to produce their potable water through desalination. In the desalination plants the salts are removed from the sea – or and after a proper treatment, water becomes potable before, distributed through the supply network. This is a necessary, in some cases, process that is however energy consuming, and with a high carbon footprint.

After the various uses, the so-called sewage or wastewater goes into the sewage system that reaches the . The water recovered from the treated wastewater is usually discharged into the sea (or rivers). However, many cities around the Mediterranean use this water, for example, for watering the urban green spaces. In some countries they make full use of the recovered water in or to recharge the underground .

In a city, rainwater that is not absorbed by the soil usually drains into the . This is a network consisting of channels and pipelines ending either into a river or to the sea (if it’s a coastal city). Stormwater and the rainwater drainage system needs to be properly designed and maintained so that the city does not flood even during heavy downpours.

The natural environment within and around the city plays a key role in the urban water cycle. Streams, wetlands, green corridors, etc. offer us many valuable services: they cleanse water, nurture biodiversity, they act as natural coolers, they retain storm and rainwater thus reducing floods etc.

In this context, there are three systems that are crucial in how the urban water cycle operates: water supply, wastewater and rainwater drainage system. These include processes starting from the water abstraction, storage, supply, distribution, sewage treatment and storm water disposal and control systems. A “smart” or efficient urban water cycle should include the reuse of treated waters, the proper use of energy and materials and the controlled emissions of the water utility operations.

Stop and wonder

Discuss in class:

How should a city’s well-designed and well-maintained rainwater system look like?
Who is responsible for the system’s design and maintenance?
What role can the citizens play?

Play & learn

The urban water cycle

Drag and drop the labels that refer to processes of the water cycle as well as to activities related to water management.

1 1 precipitation
2 2 reservoir of the water supply system
3 3 wastewater treatment plan
4 4 water collection in a dam
5 5 desalination plant
6 6 evaporation
7 7 condensation
8 8 surface run-off
9 9 water for irrigation
10 10 greywater recycling

Water-readings

Water management in a city

In cities, population and water demand is concentrated to a relatively small, dense area. This concentration increases the pressure on the water resources and the hydrological cycle. Water management within a city should firstly assess the supply and demand relation and also try to reduce the impacts of urbanization to the water cycle.

The Water Utility experts that work in the Water Supply and Seweage Services, study this “internal” urban cycle and try to promote water reuse and recycling. However, issues such as leakages, maintenance and upgrading of ageing water infrastructures, as well as the for the necessary treatments remain a a technical and financial challenge for many cities.

So in a city, sound water management means:

To ensure enough water of good quality for all.
To maintain the water supply network in order to avoid leakages.
To monitor the water quality.
To monitor the amount of available water for the city.
To conserve the quality of the water resources.
To properly design green spaces in and around the city (parks, streams, greenbelts, etc.).
To maintain the storm/rainwater system so as to avoid flooding.
To harvest and use rainwater achieving water saving and reducing the risk of flooding.
To use the recovered water and the sludge from the sewage treatment plant.
To raise awareness of the citizens in order to save and use water properly.

Sound water management in a city, an approach proposed by the CIRIA Project on Water Sensitive Urban Design, UK, 2013)

Play & Learn

According to what you have read so far, which of the following corresponds to a sound water management in a city?

A broken pipe leaks for hours.

A 24-hour hotline to report problems (leakages, damages, etc.)

Cemented corridors in parks so that people's shoes will not get muddy during rainfalls

Distribution of a brochure to consumers with water saving tips.

Overflowing grids when it rains.

Rewarding consumers who reduce water consumption (e.g. with reduced bills).

Green roofs and terraces

Water shares

Water meter

Way forward

Dive in…

Do you know about grey water? if you want to remember what greywater is

Wastewater treatment if you want to remember what black water is

Go back to the homepage!

Water in the city

In a nutshell

Our objectives

Things to use

Water-readings

Three water systems in a city

Stop and wonder

Discuss in class:

Play & learn

Play & learn

The urban water cycle

Water-readings

Water management in a city

Play & Learn

Water shares

Water meter

Way forward

Dive in…

The water basins

Water in the city

Desalination

Do you know about grey water?

Rainwater harvesting

Greywater recycling in practice

Wastewater treatment

The water cycle in a bowl!

Waterworks through time

Climate change challenges

Rainwater Harvesting Systems in practice

Reduce-Reuse-Recycle

Water resources

Where do I begin?