0:03
Karsten, we've seen in other lectures that increasingly strong heavy rains cause
floods, property damage, and pollution.
And we have heard of solutions like either large sewers or
local retention solution combined with recreation.
So how do we decide what solution is the right in a specific situation?
0:25
>> The first thing we need to decide is whether
it's the drain engineer's problems, or whether is it the city that has a problem.
So, we can choose to use the same technologies as we have always done.
So, large retention ponds, dikes, sewer systems, more pumps.
0:42
It works, it is efficient, it is relatively cheap.
Still it is expensive and people can't see what they get out of it.
So we can also look for different solutions.
One of the things that has come into play here is a change of technology.
What we see here is an animation of an area that was flooded in 2002,
exactly this is how it was flooded, precipitation runoff.
And what we see here, is that actually the high school and
the city hall are the places where it's flooded first,
whereas the soccer stadium, green areas, are completely dry.
So this is a choice, and
we are exposing the most vulnerable areas first to the flood risk.
1:24
We didn't know that when the area was constructed.
Nobody could know that, we couldn't make these calculations.
Now we can, and therefore we can choose what is it that we should flood on
an individual level, almost to the square meter, rather than on a societal level.
Saying the city should have this level then we can actually decide where should
the floods occur?
And therefore, we can choose to use the same things but
we can also start using the landscape scene.
Perhaps we should allow the soccer field to be flooded.
Perhaps we should not have just straight drain technologies and
other technologies, separate, but combine them so we have multi-functional
spaces that can serve both drainage purposes, and other purposes.
>> So what are the specific technologies that we can use for the drainage?
Are there any new technologies that are relevant?
>> The things we are working on hard right now is to model and
quantify what is the local retention measures.
So we're looking at what is the efficiency of a green roof?
What is the efficiency of soakaways?
What is the efficiency of having a swale?
All of these new technologies that we call either natural water retention measures or
nature-based solutions are things that we need to combine.
Many of them work primarily as powering sumps and
are not as sufficient for flooding.
But some of them can be merged and aligned so
that they, together with other technologies, can solve the issue.
And they have a huge benefit on a day to day value.
3:20
This looks like more like a semi-urban place.
What in the real cities?
Is there a possibilities there?
>> There are possibilities, but it also becomes difficult and in big cities,
you will see a combination of traditional technologies.
In Copenhagen they are using a massive investment in green technologies.
But they are also looking at a huge underground sewage tank.
3:46
So you will need that because the amounts of water that needs to be managed
are unbearable.
So it will be huge areas that will be allocated if you only use storage and
green facilities.
So it will be a mix in the larger cities, simply for economic reasons.
Otherwise you will need to allocate somewhere between 5% to
10% of the urban space only to water.
And that will be economically and
the urban panelist will not like us if I tried to take up that much space.
4:32
>> It's economy, but it's also the fight for urban space.
The urban planners are used to people like us calling them up and saying,
now you need to take this into account or that into account.
They like it in the old days where they could just take the urban drains and
put them into a corner and say, make a technical solution that works.
It's much more annoying when we come and say, well actually,
our analysis show that we should do this together with you to obtain that.
And Architects in Denmark have a very cultural way of solving things so
that they only look at the human interactions but
they seem to neglect other traditions.
Whereas if you go to other countries, like we also work in Australia,
there the architects are much more inspired by geographers and engineers.
So they are more used to talking to us and solving the physical problems
along with the social problems that they are focusing so much on in Denmark.
>> So there are some differences between
the traditions of how you work in Australia and how you work in Denmark?
What about if you come to more, say, poor places?
These are some of the more rich places if you have, Africa or
poor countries in Asia.
What is the thinking?
What is the strategy there?
5:53
>> When you go to search areas, really first of all you need
to look at whether somebody thinks there is a problem that needs to be solved.
So one is, that you have a problem,
the other is if somebody wishes to get it solved.
So, people are used to, in Bangladesh and
other places, that the poor people live in the areas that are flooded.
And no problem, they are the poor people, they don't lose much.
What's the problem?
6:28
So the first thing that you need there is to generate a momentum saying, for
equity reasons and for equality blah blah, then you need to do it.
And so for us coming from Scandinavia, It sometimes is a problem coming there,
seeing the problems and
finding out so nobody is really interested in solving them.
So that's the first thing that you need to do in developing countries,
is to find out, is anybody interested in solving this problem?
>> Yeah. >> And then
these kind of solutions are then the same as we do.
I mean, that way physics works the same, generating the momentum, building
alliances with what other problems that need to be solved and then solving them.
We have very good solutions.
Kuala Lumpur has one of the best solutions in actually using multi-purppose areas,
where they actually have the highway tunnel that's elevated for
flood protection, every now and then.
So when there's a big flood they have six hours to empty the tunnel for
cars and people.
7:28
And then they use it for conveyance of flooding of
water that would otherwise flood the poorer areas in the city.
So it's doable.
[COUGH] The technologies, the methods, the rationales are the same as here.
But there is the additional problem of finding out whether people want
the problem to be solved.
Henrik BregnhøjExt. Assoc. Prof.
Steffen Foss HansenAssociate Professor
