NCWR

About NCWR

Water in the city

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

Observe the pictures and choose the system they belong to (supply, sewage or rainwater drainage).


city_rain01


city_wastewater_01


city_watersystem01


city_rain02_Jim.henderson _wiki_CC


city_wastewater03


city_rain03_greywateraction.org


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.

 water-in-the-city quiz-hotspot
1
2
3
4
5
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  • 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?

Water shares


Water meter

I liked this activity:

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!

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?

The water basins

In this activity we learn what a water drainage basin is and why it is important for the experts to study it.

Continue!

Water in the city

What is the "urban water cycle"? Which are the important aspects of water management within a city environment?

Continue!

Desalination

Let's find out how sea and brackish water can become a freshwater resource!

Continue!

Do you know about grey water?

Let's find out what "greywater” is and how we can use it!

Continue!

Rainwater harvesting

Can do we collect rainwater? And how do we use it? Let's find out!

Continue!

Greywater recycling in practice

How a grewywater system is installed? Let's find out!

Continue!

Wastewater treatment

In this activity we learn about how wastewater is treated and what we can do with the treated water.

Continue!

The water cycle in a bowl!

Let's travel within the water cycle!

Continue!

Waterworks through time

Let's discover the story behind the historic fountains, cisterns and aqueducts of our town!

Continue!

Climate change challenges

Time to discuss about climate change, causes and impact and how we can cope with it.

Continue!

Rainwater Harvesting Systems in practice

What are the various types of rainwater harvesting systems? Let's find out more about them!

Continue!

Reduce-Reuse-Recycle

What is my water footprint and how can I reduce it?

Continue!

Water resources

Discovering the water resources of our region.

Continue!

Where do I begin?

Let's see why it is important to know about water in our region.

Continue!