This leaflet is developed in the
context of a Dutch - Chinese
partnership, under the Partners for
Water Program. This partnership
develops a pilot artificial recharge
water supply system in Deyang City
using the proven technologies of
the constructed wetland for source
water treatment, the artificially
enhanced groundwater recharge,
the groundwater storage and
recovery facilities, and monitoring
and modelling technologies. The
conjunctive use water supply
system will benefit from the
technology as introduced in the
Amsterdam dune system.
September 2014
Dune Water Machine, Amsterdam
zone. Problems increased from 1925
as sea water started to intrude coastal
aquifers. In addition, the delicate
dune ecology – the major sea flood
defence in the Netherlands – started
to change.
As cities grow, the challenges of
finding safe water grow with them.
And so goes the story of Amsterdam,
the capital of the Netherlands. As the
city expanded, it tapped into a reliable
source - the water from nearby
coastal sand dunes. In 1853, the water
supply lines from the dunes to the city
were commissioned. The dune water
was better than any water in the
city: it was clean with no pathogens,
filtered in the sand, and the taste was
pleasant.
However, thirty years later, signs of
limits being reached appeared as
heavy pumping caused water tables
to gradually go down in the coastal
The artificial recharge system
In 1955 things were turned around by
the development of a large so-called
artificial recharge system. In artificial
recharge, surface water (from rivers
for instance or from storm water) is
infiltrated and added to groundwater
supplies. In case of Amsterdam, water
from the River Rhine is transferred
from a navigation canal to the dune
area through a 65-kilometer pipeline.
In the dune area the water is spread
over 36 km2 with 9 km of open basins,
from where it gradually infiltrates into
the dune sand. It is then intercepted
by drains which lead the water to huge
storage ponds. From there it is treated
through (among others) aeration, slow
sand filtration and pelleting before it
is sent to the city.
Prior to being lifted to the dune areas,
the river water is pre-treated. If this
was not done the basin might fill up
with algae and the dune sands would
be polluted with heavy metals and
others. The dune system improves
the water quality but clearly does
not replace the treatment of water.
In case of the Amsterdam Dune Water
Machine, pre-treatment consists of
coagulation (to get rid of nitrates and
phosphorus), sedimentation and rapid
sand filtration.
The Dune Water Machine was switched
on in 1957. It has been working ever
since and according to its operators
from Amsterdam Waternet it is meant
to do so for another 1000 years.
The potential of artificial recharge
The Amsterdam system is not the only
artificial recharge system. Similar
systems can be found all along the
dune area in The Netherlands.
Artificial recharge has great potential
to quench the demand of an
urbanizing world. By creating reliable
groundwater reserves, high quality
water is available and a strategic
reserve is built up that can deal
with droughts and other calamities.
In many cases there is a natural
match between protection of the
water resource, nature conservation
in the recharge area and creating
possibilities for green recreation.
There are many ways to carry out
artificial recharge – only dunes will
not do – but water can also be stored
in the sandy banks of rivers or in
karstic aquifers.
•
•
•
The Leiduinen system provides
60% of the water to 700,000
inhabitants of Amsterdam
It produces 600,000 m3 of safe
water everyday.
It has also pushed back the
seawater intrusion.
Water management
in Dutch cities
Not long ago, a line was crossed when globally more people started
residing in cities than in rural areas. Not only do more people now live in
cities, but cities are getting larger and their dynamic more complicated.
The demand for water is rising steeply
, the volume of effluent is expanding
and the environment as a whole is changing. Surfaces are being pav ed
over and there is less infiltration, more run-off and more local floods.
All this calls for an entire new approach to urban water management .
The Netherlands has gone through the same challenges and has a wide
range of experiences to share.
Drainage and
infiltration
Porous pavements
Porous pavements refer to pavement
systems that are used in cities to
infiltrate (and treat) stormwater
runoff and to minimize it.
In the Netherlands, newly installed
porous pavements must have a
minimum infiltration capacity of
194 mm/h. There is a wide variety
in application and type of porous
pavements. Commonly used are
concrete pavers with wide openings
or porous concrete pavers with or
without wide openings. Plastic grid
pavers are also used.
The openings in between the pavers
allow water to be temporarily stored
before it infiltrates into a sub layer or
directly into the soil.
To prevent clogging it is important
that regular maintenance takes place.
Clogging is often a result of suspended
sediments and pollutants in runoff.
When this enters the openings
between the pavers it could obstruct
the water flow. In The Netherlands
it is recommended to carry out
maintenance (sweeping, cleaning)
when infiltration capacity drops
below 21 mm/h.
Infiltration boxes, Wierden
In a business district in Wierden,
one of the companies at the lowest
point of the area had to deal with
large quantities of rainwater during
heavy showers. To prevent flooding,
infiltration boxes were installed in the
ground around the building.
Water from the existing rooftop
gutters enter these plastic boxes with
an internal honeycomb structure. The
crates around the building can store
575,000 liters during heavy rainfalls
and are used simultanously to collect
and store water in the ground.
An additional advantage of this
system is that water can infiltrate
impermeable layers. The honeycomb
structure avoids clay and sand
particles to block the sewer system.
Roofs
Green roofs, Amsterdam
In Amsterdam, roofs take an
equal amount of 25% of the total
city surface of 291 km2. 60% of this
surface is suitable for green roofs.
Green roofs help to gradually discharge
water during intense rainshowers. The
so called “polderdak” is an example
of a green roof that is especially
designed to store water temporarily
and to discharge it with a delay.
On the roof, a small dike is
constructed with openings that can
be automatically closed when needed.
Rainwater is stored temporarily under
a layer of grass before it is gradually
released. Whether or not the openings
are shut down depends on a variety
of factors like the water level on the
roof or the expected rainfall in the
upcoming hours.
At the Zuidas in Amsterdam the first
polderdak was built with a dike of
70 mm, a surface of 1200 m 2, and
a minimum storage capacity of 84
m3. Through a water permit this
alternative type of water storage
in the private sector contributes to
the larger issue of water storage at
municipality level.
Besides water storage and gradual
discharge, green roofs have additional
advantages as they can also lower
the cities temperature and have an
isolating function. Also, they can
reduce noise.
Creativity in city
districts
Decentralized sanitation system,
Sneek
The Netherlands has a surplus of
nutrients which is growing annually as
the country imports nutrients through
food, feed and raw materials. Treating
waste water is a costly process. At
the same time, there are parts of the
world in which there is a demand for
nutrients, mainly in rising economies.
To keep a balance between demand
and supply it is important to make
efficient use of raw materials and
recycle as much as possible.
This approach was the basis of
project “Desah” in Sneek, a city in the
north of The Netherlands. “Desah”
is an abbreviation of decentralized
sanition and reuse.
In one of the districts in Sneek 280
homes were deconstructed in order
to rebuild 232 new homes. Domestic
waste water is collected and treated
seperately.
All houses include vacuum toilets and
vacuum disposal system for organic
waste. A digester converts the waste
into biogas which is used to heat
the houses. The byproducts of the
digester are eventually converted
into fertilizers used for agricultural
purposes. The treated water can
be discharged to the surface water
as the quality meets the standard
requirements.
Resident initiatives
Garden of Jan, Amsterdam On a
fallow area in the West of Amsterdam,
residents joined forces to develop
a garden which is used for leisure
purposes, but fulfills an ecological
function as well.
Residents,
garden
designers,
architects, and urban ecologists
developed the eventual design of
“Garden of Jan”, which is named after
the two streets it is located in.
In the garden, water plays a central
role. Rainwater is collected on roofs
and discharged in one of the four
ponds in which it is stored before it is
used to water the garden. The ponds
are home to many birds, frogs and
dragonflies.
All 10,000 pavers were removed
from the fallow area to give back the
natural buffer function to the soil.
Hof van Heden, R otterdamIn
Rotterdam, the residents took it one
step further. In this district a complete
residential area of 28 apartments
and 32 homes was constructed in a
participatory way.
In the WiMBY! (Welcome in My
Backyard!) initiative, residents worked
together with the housing cooperation,
architects and the municipality to set
up their own neighbourhood. Because
of smart planning it was possible, with
the help of Public Works Rotterdam,
to develop a bioswale (a landscape
element designed to remove silt and
pollution from surface runoff water),
a rainwater pond, and precipitation
drains.
The initiative has been successfully
in use and due to the integrated
approach it is a sustainable project
without additional costs.
The fruitful implementation of this
project was preceded by intense
workshops, exchange visits, and
stakeholder meetings with motivated
parties.
Creating a movement
Waterproof, AmsterdamAmsterdam
Rainproof is an initiative of Waternet
(Amsterdam’s water company) to start
a movement of citizens, entrepreneurs,
civil servants and knowledge workers.
It is an open platform to share
knowledge and best practices.The idea
behind this cooperation is to create a
more resilient city to be able to deal
with extreme rainfall, increase the
sponge effect of the city and benefit
from the rainwater.
Permeable paving, green gardens and
wadi’s: many solutions exist that can
prevent damage and, at the same
time, make the city more attractive
and liveable. A win-win situation.
Floating Buildings
Floating pavilion, Rotterdam
Probably the most famous floating
building in The Netherlands is the
“Floating Pavilion” in Rotterdam. This
construction made of three connected
hemispheres are anchored in the old
harbor. Its construction is initiated
to serve as an example of adaptation
strategies to climate change. It hosts
an information center on climate
change.
Floating houses, IJburg Amsterdam
Marlies Rohmer is a Dutch architectural
firm known for its innovative design.
In Amsterdam it developed a complete
floating neighbourhood.
IJburg district is made up of artificial
Islands. Jetty island is the first in the
IJburg chain and made up of water,
banks, jetties, and floating homes.
The floating homes are supported
by concrete “tubs” submerged in
the water to a depth of half a storey.
A lightweight supporting steel
construction is built on top.
While the main reason for floating
houses in The Netherlands is often
linked to climate change adaptation
and rising sea levels, residents give
many more reasons why they chose
living there, including multifunctional
use of space and a feeling of liberty
and being close to nature .