topos 130

no 130
2025
to po s.
flood

COVER
PHOTO:
Von Droelfzehn - Eigenes Werk, CC BY-SA 4.0
The massive tetrapod-shaped concrete
breakwaters are used for coastal protection and
are designed to break the wave energy to prevent
erosion and damage to Bari's shoreline
infrastructure. Thanks to their special shape,
they interlock with each other to form a stable
barrier against the force of the sea.
TOPOS E-PAPER: AVAIL-
Water has always been both a giver and a taker of
life. It carves landscapes, nourishes civilizations,
and shapes our cities. Yet, it also reminds us –
sometimes violently – of its immense power.
Floods have existed for millennia, but never before
has their frequency and intensity threatened
so many lives, so many homes, and so many urban
environments. As climate change accelerates,
we are entering an era where urban flooding is no
longer an exception; it is an expectation.
The numbers alone are staggering. By 2050, an
estimated 1.6 billion people will be at risk from
flooding. Entire coastal cities, from Jakarta to
New York, are grappling with the reality of rising
sea levels, overwhelmed drainage systems, and
extreme storms that once seemed rare but are
now becoming routine. This issue is dedicated to
exploring this crisis – not just as a challenge, but
as a catalyst for innovation and resilience.
Flooding is more than an environmental hazard;
it is a deeply human story. It is the child
watching murky water rise past their bedroom
window, the shopkeeper wading through a destroyed
storefront, the elderly resident being
rescued from a home that no longer exists.
Flooding erases certainty, turning streets into
rivers and displacing millions. But in its wake, it
also reveals something extraordinary: our capacity
to adapt. Cities are not just responding to
flood risks; they are rethinking the very way we
live with water.
In this issue, we delve into the world of flood resilience,
where urban planners, engineers, and
designers are pioneering new ways to safeguard
our communities. From nature-based solutions
that harness wetlands and mangroves as natural
barriers to smart infrastructure that predicts
and mitigates flood impact in real time, cities
are finding ways to coexist with water rather
than fight against it.
We take you to New Orleans, where one of the
most ambitious flood defense systems in the
world stands as both a symbol of human ingenuity
and a stark reminder of past failures. We
examine the floating neighborhoods of the
Netherlands, where water is not feared but embraced
as an integral part of urban life. And we
travel to Vietnam, where Ho Chi Minh City is
affected by flooding and subsidence.
Yet, even as we celebrate these efforts, we must
ask difficult questions. Are we doing enough,
fast enough? Are we designing cities that can
withstand not just the floods of today but those
of tomorrow? And, crucially, are we making
these solutions accessible to all, or only to those
who can afford resilience?
Flooding does not discriminate, but our responses
often do. As we explore these urban solutions,
we must remember that resilience is not
just about infrastructure - it is about people,
policies, and priorities.
This issue of toposis not just about water; it is
about the future. A future where cities adapt,
where innovation thrives, and where we learn to
work with the forces of nature rather than
against them. The rising tide is inevitable. How
we respond to it is a choice.
We invite you to immerse yourself in these stories,
to witness the challenges and the triumphs,
and to be part of a global conversation that will
shape the cities of tomorrow. Because in the
end, flooding is not just a test of engineering – it
is a test of our will to adapt and endure.
I very much look forward to your feedback on
this extraordinary issue and hope you, dear
readers, will enjoy it.
ABLE FOR YOUR DESKTOP
For more information visit:
www.toposmagazine.com/epaper
TOBIAS HAGER
Chief-Content-Officer
t.hager@georg-media.de
topos 130 005

CONTENTS
OPINION
Page 8
CURATED PRODUCTS
Page 100
THE BIG PICTURE
Page 10
METROPOLIS EXPLAINED
Page 12
URBAN PIONEERS
Page 14
A CITY RISING ABOVE THE TIDES
Ho Chi Minh City
Page 40
REIMAGINING THE FLOW OF NATURE
An Introduction by Kongjian Yu
Page 18
THE GREAT FLOODS
Valencia's flood disaster
Page 24
“ACTIVATE RISK EDUCATION FOR THE
POPULATION”
An Interview with Jorge Olcina Cantos
Page 32
PICTURE SERIE: GLOBAL WARMING
Dubai
Page 38
“TECHNOLOGICAL INNOVATION, CAPACITY
BUILDING AND THE INVOLVEMENT OF LOCAL
STAKEHOLDERS”
An Interview with Felix Bachofer
Page 48
PICTURE SERIE: GLOBAL WARMING
Jakarta
Page 52
FACTS AND FIGURES
What is the name of Tokyos flood defence system?
Page 54
BETWEEN VISION AND ADAPTATION
A Portrait of Copenhagen
Page 56
“PEOPLE ARE VERY AWARE OF THE RISKS”
An Interview with Ina Holleufer Jaller
Page 64
PICTURE SERIE: GLOBAL WARMING
Tolosa
Page 68
“WE CAN HANDLE IT”
Interview with Co Verdaas
Page 78
PICTURE SERIE: GLOBAL WARMING
Washington D.C.
Page 82
A CITY SEEKS A WAY OUT OF THE WATER CRISIS
Chennai: the megacity on the Bay of Bengal
Page 84
A THREATENED CULTURAL METROPOLIS
The metropolis in southern Ghana: Accra
Page 92
CONTRIBUTORS
Page 100
CITY GAMECHANGERS
Page 112
EDGE CITY
Page 114
IMPRINT
Page 113
WATER IS IN OUR GENES
Rotterdams Solution with Water
Page 70
Photos: Red Nguyen on pexels, Sjoerd Bracke & Cuno de Bruin
006 topos 130

OPINION
FLOODS – WE
NEED A
PARADIGM SHIFT
Storms cause billions in damage! According to estimates from the insurance industry,
flooding after heavy rainfall caused €2.5 billion in damages in Germany alone in 2024.
The UN reports that by 2050, 1.6 billion people worldwide will be at risk of flooding.
008 topos 130

Opinion
Floods and inundations are direct consequences
of climate change. The Robert Koch Institute
reported over 7,000 heat-related deaths per year
in Germany in 2017 and 2018. The economic
impact of heat, particularly in terms of reduced
productivity, is also significant. Working comfortably
– whether outdoors or in an office – is
nearly impossible at 30 degrees celsius or higher.
However, there are two sides to the same coin:
too much water on one side, too little on the
other. The real challenge is that heatwaves and
droughts are becoming longer and increasingly
overlapping. Urban vegetation dries out, the
natural cooling effect of evaporation in cities
diminishes, and drought-related damage in
agriculture and forestry worsens. Drinking
water will become scarcer, and competition for
water resources will intensify.
Solving the Rainwater Dilemma
The rainwater dilemma – sometimes too much,
sometimes too little – will be one of the greatest
challenges of the future. When excess water is
available, cities and landscapes must retain it
like a sponge to prevent heat stress and drought.
The natural water balance, with a high proportion
of evaporation (e.g. 70 per cent of rainwater
in eastern Germany), minimal runoff, and a
moderate level of infiltration, points the way
forward for sustainable rainwater management.
A Paradigm Shift: From Wastewater to Resource
Future urban and landscape planning must aim
to develop runoff-free environments. Rainwater
is one of the most valuable resources we have.
The widespread classification of rainwater as
"wastewater" in many countries is fundamentally
incorrect. A paradigm shift is needed –
from drainage-focused approaches to integrated
water resource management.
The Sponge City Principle as a Strategy
It is now recognized that expanding sewer systems
is not a viable long-term solution for heavy
rainfall events. Instead, the sponge city principle
seeks to retain rainwater within urban areas
through decentralized solutions, enhancing soil
capacity as a natural reservoir. A water-saturated
soil system enables evaporation during heatwaves
and supports vegetation during dry periods.
Despite growing awareness, the large-scale
implementation of sponge city concepts remains
in its early stages—cities are slow to adapt.
Classic Flood Protection: An End-of-Pipe
Technology
For decades, landscapes have been systematically
drained—wet meadows dried out, drainage
ditches dug, agricultural land drained, small
water bodies filled in, and rivers straightened.
This widespread drainage has severely degraded
soils, reducing their ability to store both water
and carbon. As a result, runoff rates continue to
accelerate.
Traditional flood protection measures, which
come with enormous costs, focus on reactive
solutions: raising dykes, expanding riverbeds,
creating flood polders, and restricting construction
in floodplains. While these measures are
necessary, they address only the symptoms
rather than the root causes of the problem.
Instead, water must be retained where it falls.
The Sponge Landscape Principle as a Strategy
To address this challenge, landscapes must be
transformed into sponge landscapes. A fundamental
paradigm shift is required—alongside a
comprehensive program to retain rainwater
within the landscape. Strategies include paludiculture
(wetland farming), small reservoirs,
repurposing drainage systems for irrigation,
restoring wet meadows, floodplains, and wet
forests, and converting drainage ditches into
water-rich landscapes.
New ideas and visions are needed for designing
retention landscapes. Critical questions arise:
How can this new type of retention landscape
be designed? What new value chains can be
developed? What legal frameworks and instruments
are necessary? Who will take responsibility
for implementing these changes?
Transforming Landscapes: A Major Challenge
Unlike cities, buildings, or public spaces, landscapes
have no single architect, planner, or client.
They are shaped by a multitude of stakeholders
– farmers, landowners, policymakers,
and businesses – whose decisions are influenced
by market forces, funding programs, inheritance
structures, and complex legal frameworks.
Achieving transformation requires systemic
adjustments and collaboration among all
these actors.
The shift from drained landscapes to sponge
landscapes – just like the urban transition to
sponge cities – will be a generational challenge.
Success will only be possible through collective
action. The key lies in embracing the sponge
principle, which unifies flood prevention, heat
mitigation, and drought resilience into a single,
integrated water management strategy. Much
work remains to be done!
CARLO BECKER is a landscape architect (AK Berlin)
and one of the founders of bgmr Landschaftsarchitekten
GmbH in Berlin.
ARNO WALZ is a urban planner (AK Berlin) and is
managing partner of bgmr Landschaftsarchitekten
GmbH in Berlin.
topos 130 009

Valencia the third
largest city in Spain
played a central role as
the cultural and
economic center of the
Mediterranean region.
Photo: travelnow.or.crylater on Unsplash
topos 130 025

“It resembles a garden, with magnificent buildings; it seems to me the most beautiful
that my eyes have ever seen,” the Spanish poet Lope de Vega once wrote about
Valencia. In 2024, the face of the city and the region was marred by a devastating
flood disaster. A look at the role that water has played in the city for centuries and
and how lessons can be learned from the past.
The Romans, who founded the city on a river island in one of the meanders
of the Rio Turia in 138 BC, laid the foundations for de Vega's praise
of the city. The name “Valentia” means something like “the beautiful” or
“the powerful”. From then on, what is now the third largest city in Spain
played a central role as the cultural and economic center of the Mediterranean
region.
Valencia's urban development reflects the changing eras of its history, characterized
by cultural influences, economic upswings and downswings as
well as urban transformations. In 714, the city came under Moorish rule
thanks to a capitulation treaty that allowed the old inhabitants to coexist
peacefully with the new arrivals. Over the next 500 years - from 711 to 1238
– Valencia experienced a period of prosperity that is still visible today, both
in the city structure and in elements such as the irrigation technology of the
Huerta area or the so-called Tribunal de las Aguas, the water court.
When the Rio Turia overflowed
The reconquest by Christian troops in 1238 then led to a reorganization
of the city. New Christian churches were built and Gothic architecture
spread. In the late Middle Ages and during the Renaissance, Valencia
gained great importance through the trade in silk and other goods. The
Lonja de la Seda, the Gothic silk exchange, is still a visible relic of this economic
heyday. It was declared a UNESCO World Heritage Site in 1996.
Due to the European invasion of America, global trade in Europe eventually
shifted to the Atlantic ports, heralding Valencia's gradual economic
decline. In the course of industrialization, metal industries, textile factories
and power plants developed in Valencia at the beginning of the 20th
century. The cityscape also underwent profound changes with new infrastructure
projects such as the construction of the Estación del Norte and
the expansion of the port facilities. At the same time, the city grew rapidly,
which led to partly unplanned densification. Modernisme architecture,
as can be seen in the Eixample district, brought a new aesthetic, but often
at the expense of traditional buildings. In the 20th century, especially during
the Franco dictatorship, it was not only the residents who suffered
from political oppression, but also the city - from uncontrolled urbanization
and the loss of historic buildings.
In 1957, another tragic event occurred that would drastically change the
cityscape. For thousands of years, water and the proximity to the river had
played an important role for Valencia. The Romans chose the site explicitly
because of its favorable location at the winding end of the Turia. The
river not only served as a water supply for the city, but also as a natural
moat for the city's defense. Goods could also be transported on it. At the
time of its foundation, the sea level was around four meters below today's
level. The higher ground on which Valentia stood was therefore spared
flooding for a long time. However, major floods were recorded in 1356 and
1589, both of which prompted the construction of dams. Even in 1949,
during the Spanish Civil War, a flood washed away poor and refugee settlements
on the banks of the river. However, the renewed construction of
dams did not prevent the devastating flood of October 14, 1957, which
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flood
A CITY RISING
ABOVE THE TIDES
SUSANNE KARR
040 topos 130

Smart traffic management,
renewable energy,
digital public services,
smart urban planning,
and E-government are
becoming integral to
Hoh Chi Minh City.
Photo: Red Nguyen on pexels
topos 130 041

Ho Chi Minh City buzzes with a lively social vibe, open attitude, and some of the
world’s best street food. This vibrant metropolis offers a unique blend of tradition
and modern urban life: it’s not the most relaxing spot, but is packed with character,
charm, rich culture, and the occasional chance to swim in the streets.
As dawn breaks, the skyline glows in shades of pink and orange, reflected
in the Saigon River. Ho Chi Minh City is made for early birds, with activities
starting as soon as the new day begins. Motorbikes and scooters draw
colorful patterns through traditional narrow alleys and wide boulevards
lined with century-old French colonial architecture. Most likely you will
soon meet street vendors preparing their morning specials: bánh mì
sandwiches stuffed with pickled vegetables and pâté. And with it freshly
brewed cà phê sữa đá - Vietnam’s signature iced coffee sweetened with
condensed milk. At the famous Ben Thanh Market with its central clock
tower, you can find fresh produce, local handicrafts, souvenirs, clothing,
jewelry, and a variety of foods.
A short walk away, not far from the Saigon River, is the famous Nguyen
Hue Walking Street – a real oasis between the busy roads. You might find
small businesses with an assortment of typical traditional products: “the
silk fabric and the tortoiseshell accessories in glass cases; the frozen pulps
of jackfruits and durians; the burlap snacks of dried arnica and lemon
grass stalks…”, as novelist Lan Cao describes the variety offered in typical
Vietnamese shops.
In this area, with its wide open spaces and a blend of imperialist and
modern buildings and local shops, you might observe students in crisp
white uniforms pedaling their bikes. White uniforms are a traditional
attire for high school students in Vietnam, mandatory in most public and
private high schools. Even though motorbikes and scooters seem to be all
over the place, bicycles remain popular for high school students. But if
you are looking for a more contemplative start to the day, you might want
to see one of the pagodas in the more traditional districts or in Chinatown.
The ancient pagodas are adorned with red lanterns, and the intense
smoke of incense swirls around, defining the atmosphere. This is Ho Chi
Minh City – a place where tradition and modernity collide, and temples,
dizzying skyscrapers and designs reminiscent of French influence reside
side by side. Pastel-colored apartment buildings show architectural features
like ornate balconies, high ceilings and shuttered windows typical of
19th-century Paris. As a visual and atmospheric counterpoint, street
murals narrate tales of the city’s history and resilience. They are part of
the city’s effort to combine art and history. Often, they depict significant
events, figures, and cultural aspects of Vietnam, especially its struggles
during the Vietnam War and the country’s resilience.
Underground living spaces
Like Korea, Vietnam has been the scene of a proxy war between the USA
and the communist bloc. A prominent silent witness of the wartime is the
extensive network of subterranean tunnels, most famously the Cu Chi
Tunnels, just outside of the city. They were built during the Vietnam War
(known locally as the American War) and served as a vital base of operations
for the Viet Cong. Today, parts of the Cu Chi Tunnels have been preserved
and are open to visitors, offering a glimpse into the ingenuity and
resilience of the Vietnamese people during the war.
The network stretches over 250 kilometers and includes underground living
spaces, kitchens, storage facilities, and even hospitals. The tunnels
were ingeniously designed with air vents, booby traps, and hidden
entrances to evade detection by enemy forces.
The region has long been an object of desire. Archaeological findings and
042 topos 130

flood
historical records show that in the 4th century there was the Khmer seaport
“Prey Nokor”. A Funan temple from that time was discovered at the
site of the current Phụng Sơn Buddhist temple. Saigon's ascent began in
the 17th century under the Nguyen lords, who established a trade gateway
to the Mekong Delta and South China Sea. Over centuries, the city faced
multiple invasion attempts, including by China and the Mongols.
In the 19th century, French colonial rule reshaped Saigon, making it the
capital of French Cochinchina. Grand boulevards and European architecture
modernized the city but came at a cost. The colonial era brought
resource exploitation and suppressed local freedoms, leaving a mixed legacy
of progress and pain. Yet, through every challenge, the people of Saigon
have demonstrated an enduring spirit. It is as if people are following
a life-affirming attitude expressed by Thich Nhat Hanh: “The seed of suffering
in you may be strong, but don’t wait until you have no more suffering
before allowing yourself to be happy.” The famous Buddhist monk was
a highly respected spiritual teacher and renowned peace activist who
himself has overcome much adversity and persecution.
60 centimeter above street level
Resilience is also in high demand today, although in a completely different
context. Beneath the energy and lights and Ho Chin Min City’s
dynamic charm, the metropolis faces significant challenges.
Because of the city’s location in the Mekong delta and the low elevation
above sea level, Ho Chi Minh City is one of the city’s most vulnerable to
climate change. Other cities facing similar risks include Jakarta, Bangkok,
Miami, and Dhaka, which all grapple with comparable problems. Another
serious factor for quality of life and positive urban development is the
growing population pressure, due to the city’s expansion. Ho Chi Minh
City is the economic heart of Vietnam. It is a megacity where one quarter
of the country’s GDP is produced. With continued migration from other
provinces, the city is experiencing urban sprawl and strain on its infrastructure.
These risks are expected to intensify in the future.
From the mangroves on its outskirts to the towering skyscrapers downtown,
the geographic setting poses inherent challenges from the get-go
for Ho Chi Minh City. The low position above sea level - about 5 meters
in the city center and 16 meters in the suburbs - makes it highly susceptible
to flooding. The city’s 15 kilometer coastline along the East Sea and its
position on the Mekong Delta further heighten its vulnerability and make
it particularly prone to storm surges.
In October 2024, high tides exceeded 1.65 meters. In combination with
heavy rainfall, significant flooding disrupted daily life and commutes in
parts of the city.
These challenges are related to rapid urbanization, land subsidence, and
climate change. There are several reasons for this:
1. The global sea level rise is driven by melting ice caps and thermal
expansion of water. This increases the height of tides along the city's
long coastline.
2. Higher tides overwhelm the city's drainage systems, especially in
low-lying areas.
3. Climate change fuels stronger and more frequent storms. Higher
storm surges can flood urban areas, destroy infrastructure, and disrupt
daily life.
4. Climate change is associated with more intense and irregular rainfall.
When heavy rains coincide with high tides, flooding worsens dramatically
due to inadequate drainage systems.
Flooding, exacerbated by the climate crisis, has long been a challenge for
the city, particularly during the rainy season and rising tides from the
East Sea. While the risk of flooding is significant, it has been considered a
normal occurrence, with water levels often rising 60 centimeter above
street level. This poses dangers for traffic, particularly scooters, and causes
substantial damage to parked vehicles and building foundations, leading
to mold issues.
Too much water
Imagine the water reaching a height of 60 centimeters! This is not only
dangerous when you’re driving one of the thousands of scooters. Apart
from the danger of traffic accidents, the damage to parked vehicles is con-
topos 130 043

INTERVIEWEE: INA HOLLEUFER JALLER
INTERVIEW: ANNA MARTIN
“PEOPLE ARE VERY
AWARE OF THE RISKS”
The Danish municipality of Køge has recognised its risk for flooding from
the sea and is taking action: For years, they've been planning and realising
one of the largest coastal protection projects in Denmark involving dikes
and protective walls. Project manager Ina Holleufer Jaller explains in an interview
how nature conservation areas caused some challenges, why most
of the citizens consent to paying for the project's costs and how the barriers
may influence the relationship between people and the sea.
Køge Dike is considered one of the largest coastal protection projects
in Denmark. When completed, its height will be around 2.8 metres
above sea level, and it will run along most of the municipality’s coastline
from north to south to protect around 22,000 citizens and their
homes from flooding and storm surges from the sea. Why does Køge
need such comprehensive protection? What distinguishes the city and
its location from others?
The location is close to water, but it's also very low in terrain. It's very flat,
even a few kilometres inwards from the coast, and that's the problem. It is
a barrier coast with dunes, lagoons and salt marshes. I think that the present
nature used to extend further inland.
Did you experience certain events like flooding that prompted this
specific project?
The project started when we had to make a climate plan which was around
2014 to 2015. We had a look at how the climate change would affect our
city from different perspectives – both flooding from the sea, but also due
to massive rainfall. The resulting plan showed how big the problems were.
The biggest one for our municipality is flooding from the sea, because so
many people would be affected. Rain could also cause some problems, but
it would have a smaller impact on local people. That was the project’s start,
and we have been working on it ever since. According to the Danish coastal
protection law, there are several steps that you have to go through for
such a project. In 2016, the city council decided to take the initiative to
raise a coastal protection case. So, the administration started working on
the project, for example by conducting different analyses for the preliminary
proposal. In 2018, the city council decided to advance the project
with a second step. This was the political “okay” to work on implementing
the project. It has been a long time from the start to where we are now.
In 2017, we had a big flood in the form of what we called a quiet storm: The
water rose, but without wind or waves at Køge’s coast. A lot of people saw
how many problems even a small storm can cause. It was the first time in
064 topos 130

flood
The Danish municipality
of Køge is planning to
build a dike to protect its
citizens, their homes
and surrounding areas
from flooding from the
sea. The protected
Natura 2000 area on the
coast to the north of the
city - seen here after the
flood in 2023 - posed
challenges for the
dike's planners.
Photo: Køge Kommune
VITA
INA HOLLEUFER JALLER is a landscape architect and project manager of the Køge
Dike project in the Danish city of Køge. Besides the dike project, she’s working with
urban development projects in Køge and has been working on projects e.g. in parks
and recreational areas as well as climate adaption projects.
topos 130 065

flood
WATER IS
IN OUR GENES
JULIANE VON HAGEN
070 topos 130

‚Delta Works‘ is a
widespread system of
dams and storm surge
barriers along the
Dutch rivers and
coastlines.
Photo: Sjoerd Bracke & Cuno de Bruin
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flood
The country’s name Netherlands already hints at its situation of lying ‘low‘, of being
below sea level. Therefore, the Dutch have had experience in dealing with water for
centuries. Nevertheless, the current climate conditions challenge them again. Rotterdam
is currently searching for new solutions to live with the water.
Photo: Chay Kelly via Unsplash
As the word ‘nether‘ already indicates, large portions of the country lie
below sea level. Many parts of its territory are reclaimed from either lakes
or parts of the North Sea. As early as the 13th century, the delta of Rhine,
Maas and Schelde in the southwestern part started to dry out and islands
of sand grew. Protected by a dike, they later became usable land. Around
1600, technical developments made further poldering possible. Especially
windmills, still today icons of the Netherlands, helped to pump water
and created habitable land. Centuries later, fuel driven pumps took over.
Until today, an intricate system of pumping is needed to manage the
water in Holland.
Despite ongoing efforts to gain new land and protect existing areas by
dikes, a horrible flood surprised the Netherlands in 1953. Caused by a
heavy storm surge, several sea defenses where overwhelmed and large
areas in the Southwest flooded. Almost 2,000 people lost their lives. With
a realistic perspective on the future, the Dutch expected similar events to
reoccur and started strengthening their coastal defenses. Today’s ‘Delta
Works‘ is the result of this early foresight; a widespread system of dams
and storm surge barriers along the Dutch rivers and coastlines.
In addition to this protection, the city and port of Rotterdam asked for
more and so the ‘Maeslantkering‘ was built. This is a movable gate that
closes automatically once the national water level reaches 3 meters in Rotterdam.
With doors of over 200 meters in length, these two huge metal
gates stop the water pushing from the North Sea into the river Meuse and
ultimately into the city. When the gate is shut, the shipping traffic into
Rotterdam harbor is interrupted. But since the gate’s completion in 1997,
it has only been closed automatically once; in December 2023 when high
water levels and the storm Pia came together. Although Maeslantkering
was only activated once in almost 30 years, the Dutch are worried about
the impacts of climate change. Therefore, they are experimenting with
different strategies to adapt their water management to future conditions.
Port and City of Rotterdam
Rotterdam is the second largest city of the Netherlands with over 600,000
inhabitants and an important port. With access to the North Sea, via the
river delta of Rhine, Meuse and Schelde, Rotterdam’s harbour is the largest
in Europe. This connection makes the port an important logistic and
economic hub in the Netherlands, and for central Europe. Therefore, it is
no surprise that the Dutch are keen to protect this asset from the consequences
of a changing climate. But the city itself, known for its innovative
architecture and experimental urban development, also needs to worry
about its levels of resilience.
For a long time, canals and pumps managed to keep a stable water level in
the city. With about 85 per cent of the city lying below sea level, over 1,000
pumping stations manage rain and sewage every day. However, extreme
weather events put Rotterdam’s water management system under stress.
Despite the country’s long history of protecting its land from water, the danger
of coastal flooding remains and puts particularly the city’s port at risk.
Fluvial flooding also has a negative impact on local ecosystems, infrastructure
and urban homes. The largest danger for urbanised areas however is
pluvial flooding, especially where heavy rainfall hits impervious surfaces.
Apart from dangers resulting from too much water, periods of drought
are also expected to become routine. They will not only have negative
effects on ecosystems, but also on water quality, and the city’s economy
when low river levels obstruct the shipping traffic.
‘Living with water’
The Fourth Dutch Water Management Memorandum of 1998 marked a
distinct shift towards a new approach: to live with water. While in the past,
the idea was to “pave, pipe and pump“, Rotterdam now aims to become a
sponge city and accordingly, all measures and projects will help to “delay,
store and drain“. Following this motto, Rotterdam implemented diverse
projects, from urban plazas that change into water basins, to parking garages
that can be flooded and storing water in green areas and on roof tops.
Floating in Water
The most Dutch interpretation of ‘living with water‘ is to move buildings
onto the water and let them float. If a structure can swim, it can adjust to
changing water levels, as the Hafenlofts in Nassauhaven prove. The starting
point for these eight floating homes in a long-abandoned harbour
basin was the search for space due to increasing housing needs. And since
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flood
space was scarce, the city council allowed building on water. In 2012, it
launched a request for a pilot project of “ an excellent, varied, and floating
living quarter, which positively contributes to the Feijenoord district“. In
2022, eighteen floating houses were completed. All of them built in a sustainable
manner, fully carbon neutral and with easy access to electric
shared cars, charging points and electric bicycles. The most challenging
part of the project was, however, the tidal changes of the site. It fluctuates
by up to two meters. Therefore, each house is built on an unsinkable,
swimming concrete pontoon. Public Domain Architecten from Rotterdam
developed the Hafenlofts as a pilot project and consider it a new perspective
on sustainable urban development.
The idea to move urban elements onto the water is not limited to housing.
Another group of innovators developed a floating farm, and floating pavilions
and even a floating forest can be found in Rotterdam. In 2021 the headquarter
of the Global Center on Climate Adaptation moved into an office
building floating in the basin of a former industrial harbour. The NGO now
shares their new office space with the building’s architects: the Powerhouse
Company. They constructed the three-storey office building on a set of
floating concrete barges. Its wooden structure contributes to the building's
low carbon footprint and ensures it is light enough to float. The ‘Floating
Office Rotterdam‘ is the largest building of this kind in the world so far.
Storing Water in the City
Next to experimenting with building on water, the City of Rotterdam
integrates possibilities for storing water into their urban design. One
example is Benthemplein, a public space which also serves as storm water
storage. The typology of the water square was developed by De Urbanisten
for the International Architecture Biennale Rotterdam in 2005 and
became official policy in the Rotterdam Waterplan in 2007. It took six
years from the idea and concept, to policy and final design. In 2013, the
project officially opened. The water plaza now consists of three basins:
two shallow ones on the sides receiving water whenever it rains. The
deeper one in the center only gets wet when rain continues for longer. It
collects the water from the larger area around the square. Most of the time
the water square is dry and used as recreational space; for skating and
moving around, for sitting and relaxing. In the participatory development
process, residents wanted a dynamic place for young people and also
wished for the water to be visible while running over the square. Hence,
Benthemplein pursues a multifold strategy: contributing to improving the
quality of public space, strengthening the identity of a neighbourhood,
and storing water in case of heavy rain.
When heavy rain persists in Rotterdam, when the water management system
is overwhelmed, the parking lot of the Museumspark can become
Photo: Georg Eiermann via Unsplash
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