Wharf with cloudburst outlet. The drains are fitted
with non-return valves to prevent sea water from
entering
CLIMATE RESILIENCE PROGRAMME FOR
STORM WATER AND SEWER SERVICES
The City of Copenhagen has prepared a Climate
Adaptation Plan to safeguard the city against
climate changes, enabling us to manage more
and heavier rainfall, rising sea levels and warmer
weather.
On 2 July 2011, Copenhagen was hit by a cloudburst so
extreme it permanently changed the way we handle
downpours in Danish cities. Copenhagen resembled
Venice, with every street a canal. The rain gauge
in the Botanical Gardens in Central Copenhagen
recorded a record-breaking 135 mm. of rain in the
space of just a few hours.
The entire city was flooded and the damage caused
has been estimated to amount to a whopping
DKK 7 billion. In the wake of the disaster, the City
of Copenhagen and HOFOR agreed on a DKK 20
billion Cloudburst Management Plan, with a 20year timeframe to make Greater Copenhagen more
resilient to cloudbursts in particular and heavier
rainfall in general.
Financing adaptation in Denmark
Sewer and storm water management
has
traditionally been financed through water taxes.
Surface solutions, such as canals, retention basins,
etc., are also financed through water taxes, but this
is only permitted if they can be clearly distinguished
as storm water management, and do not have
recreational value. This is because urban space
improvements must be paid for by the city – not by
the utility.
However, since climate change adaptation calls for
solutions that are inventive and comprehensive,
compartmentalizing solutions may lead to less than
ideal solutions.
HOFOR has worked to change the legislation
on financing adaptation, and now storm water
management solutions that also improve the urban
space – so called ‘mixed projects’ – may now be
financed by HOFOR while still owned, constructed
and maintained by the city. Projects on privately
owned land are subsidized by the utility.
The plan
The main focus of the Cloudburst Management Plan
is to direct rainwater by gravity towards the nearest
body of water, mainly the sea, if at all possible.
Read more at www.hofor.dk
HOFOR stands for Greater Copenhagen Utility. We deliver water and wastewater in a number of municipalities in the capital area. Additionally to this we supply Copenhagen with district heating, city gas, and district cooling - and are currently
building wind turbines both within and outside of Copenhagen.
SEPTEMBER
2016
A line drain near ’Holmens Kirke’ church in the center
of Copenhagen
Surface solutions are used as well to delay and retain
the water.
The plan consists of more than 300 projects, and
annual project packages are agreed on by HOFOR
and the city council.
The projects are of varying size and complexity,
ranging from simply knocking holes in the wharves to
allow rainwater to run unhindered into the canals, to
excavating giant, metro-sized storm-water tunnels
under the city.
Storm water tunnels
Two such tunnels are almost complete at Hvidovre
and Østerbro, while more tunnels are being planned
in Valby, Brønshøj and Vesterbro.
Projects of a smaller scale include a new system
of line drains introduced in central Copenhagen at
Slotsholmen, Havnegade and Toldbodgade, which
direct storm water to the harbour in a separate, new
pipe system, and outlets with non-return valves
leading surface water to the harbour.
Surface solutions focus on creating ‘blue and green
spaces’ that integrate water in the urban space and
create green corridors, which not only increases
biodiversity, but also combats urban heat island
effects.
Water retention parks have been completed at:
• Sankt Kjelds Kvarter
• Sankt Annæ Plads
• Valbyparken
And there’s many more on their way.
The parks are being reshaped to receive large
volumes of water without preventing their daily use,
mainly by lowering the lawns and remoulding the
skateparks.
AND IT WORKS!
• When the storm “Bodil” hit on 6 December 2013, the water level in the harbour was
1.68 metres above normal sea level. The nonreturn valves installed in the cloudburst pipes
kept tightly shut and prevented sea water
from entering the pipes.
• The cloudburst on 31 August 2014 was bigger than a 100-year flood, and the cloudburst
solutions installed were overloaded with a larger volume of water than they are designed to
take. However, the cloudburst solutions worked as they were supposed to and prevented
flooding in the area.
Read more at www.hofor.dk
HOFOR stands for Greater Copenhagen Utility. We deliver water and wastewater in a number of municipalities in the capital area. Additionally to this we supply Copenhagen with district heating, city gas, and district cooling - and are currently
building wind turbines both within and outside of Copenhagen.
SEPTEMBER
2016