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hould we stop building in some places, or should
we actually be building dikes? Or is it better to
set aside flood-prone areas for agriculture and
fishing? The unpredictability of climate change
makes it difficult to predict the best approach to
infrastructure for the long term, particularly if an
area under threat is economically important.
Ad Jeuken, a climate adaptation expert, believes that this
requires greater flexibility in decision-making about local and
regional water management. ‘We should be concentrating
less on getting everything arranged for generations to come,
and more on taking different scenarios and the interactions
between them into account. That includes demographic and
socio-economic scenarios.’
Agencies managing water systems have to
take decisions about infrastructure that will be
in place for fifty or a hundred years. How do you
go about achieving that?
‘To start with, you try and decide what you want to achieve
during that time and which developments can undermine
your objectives. Then you select a range of possible climate
scenarios. You try to combine those as well as possible
with the data that you already have about floods and water
shortages. For example, let’s say that heavy rain now results
in flooding once every twenty years. You combine that with
data from the climate scenarios and you may find that the
flood frequency for 2050, for example, increases to between
once every ten years and once every five years. That means
you need to take action.’
Doesn’t that just mean building or raising
dikes?
‘That is very much the question. You also have to keep
demographic and economic developments in mind. A flood
frequency of once every five years may be acceptable in
sparsely-populated agricultural areas. In that case, a warning
system and damage repair may be enough. However, a lot of
urban development is actually located in flood-prone deltas
because it is there that the trade centres have traditionally
been located. The trick is to strike exactly the right balance.’
Different climate scenarios often produce
a picture that isn’t clear or straightforward.
That makes adaptation even more difficult.
‘What matters is to develop a strategy for the long term that
is flexible enough to respond to unexpected developments.
The traditional planning approach comes up short because
you don’t know what you need to keep in mind. So that
requires what we call an adaptive planning approach. That
factors in not only different futures but also the different
pathways leading to those futures. On the basis of the
present scenarios for precipitation patterns, the first step
will be, for example, to try to raise the discharge capacity
of a river by creating overflow areas. If the river discharge
increases more than expected, you can always decide to
strengthen the dikes later. But you can also ensure that
specific urban areas under threat are protected from flooding,
depending on economic and spatial developments. The trick
is to enhance your administrative and policy flexibility so
that you can respond to change without pushing up costs,
and also without taking more risks.’
It’s a long-term business. How do you get the
public and politicians on board? You can’t
maintain a permanent sense of urgency.
‘That’s right. That’s why it’s important to combine flood
risk management with other objectives. Jakarta is a case
in point. As a result of land subsidence – and not even an
actual increase in the sea level – the flood risk there has risen
‘TRADITIONAL PLANNING
METHODS COME UP SHORT’
Increased flood risks and longer dry periods require changes in infrastructure.
‘But climate change is so unpredictable that administrative flexibility is
really stretched’, says climate adaptation expert Ad Jeuken.
BY JOOST VAN KASTEREN
10
DOSSIER
CLIMATE ADAPTATION