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Consequences of a flood in Kristianstad, Sweden : a GIS-based analysis of impacts on important societal functions

Sjögren, Jonas LU (2017) In Master Thesis in Geographical Information Science GISM01 20171
Dept of Physical Geography and Ecosystem Science
Abstract
According to a recent report from the Swedish Civil Contingencies Agency, the city of Kristianstad is considered as one of the most vulnerable in Sweden regarding consequences of a flood. Being protected by a barrier system, a failure would most likely have serious impact on the city. As parts of the city are situated below sea level, a heavy rainfall may cause considerable consequences since there is no natural outlet and all water has to be pumped out.
To quantify the consequences, the master thesis “Consequences of a flood in Kristianstad, Sweden”, focuses on important societal functions and the impacts to individual objects at different water levels. A disastrous consequence has been defined for 125 important societal objects in the... (More)
According to a recent report from the Swedish Civil Contingencies Agency, the city of Kristianstad is considered as one of the most vulnerable in Sweden regarding consequences of a flood. Being protected by a barrier system, a failure would most likely have serious impact on the city. As parts of the city are situated below sea level, a heavy rainfall may cause considerable consequences since there is no natural outlet and all water has to be pumped out.
To quantify the consequences, the master thesis “Consequences of a flood in Kristianstad, Sweden”, focuses on important societal functions and the impacts to individual objects at different water levels. A disastrous consequence has been defined for 125 important societal objects in the city, which relates to a water level where the activities at the object must stop due to security, accessibility or other reasons.
Consequences of a water level at elevations from -2.4 m up to +4.0 m with 0.1 m steps have been investigated and related to characteristic discharge in the river Helge å, as well as to characteristic sea water levels in the Baltic Sea. The objects chosen are all situated within the +4.0 m flood area and are identified by using the priority classes 0-4 of the Styrel project, a plan that regulates disconnection of electrical power in case of transient power shortage.
Two key figures are used to quantify the impacts on the city; the number of affected objects related to number of total objects, and affected objects providing service to a main part of the population related to total number of objects of this category. Four scenarios have been studied that would reflect a 100-year event; three with high discharge in the river Helge å and a barrier failure, a fourth scenario with a heavy rainfall.
A consequence of a west barrier failure is that 16% of the objects with important societal function would have to close. This includes 27% of the objects providing service to a main part of the population. The figures for a Hammarslund barrier failure is 59% and 45% respectively, and for a simultaneous failure of the two barriers 70% and 58% respectively. A 100-year precipitation would affect 32% of the objects, including 12% of the objects providing service to a main part of the population. The most vulnerable object category at a 100-year event is retirement homes, while freshwater boreholes belong to the least vulnerable. In case of a 100-year precipitation, the hospital administration is found to be in special need of protection. (Less)
Popular Abstract
Since ages, living with a constant risk of being flooded has become a part of daily life to many citizens of Kristianstad. For some people this is not much to take notice of, yet for others it may sometimes affect their night sleep. All they can do is to rely on the city´s Great Wall – that it will last on the day of the big flood.
The whole thing goes back to the beginning of the 17th century, when the Danish king Christian IV ordered Kristianstad to be built in the middle of a swamp, easy to defend against the Swedes. It was a time of battles where the city under a period – however short – represented a stronghold in the region. As time went by the city became Swedish territory, and to expand the city large areas of low-lying wetlands... (More)
Since ages, living with a constant risk of being flooded has become a part of daily life to many citizens of Kristianstad. For some people this is not much to take notice of, yet for others it may sometimes affect their night sleep. All they can do is to rely on the city´s Great Wall – that it will last on the day of the big flood.
The whole thing goes back to the beginning of the 17th century, when the Danish king Christian IV ordered Kristianstad to be built in the middle of a swamp, easy to defend against the Swedes. It was a time of battles where the city under a period – however short – represented a stronghold in the region. As time went by the city became Swedish territory, and to expand the city large areas of low-lying wetlands was walled in.
Notable is that we find Sweden's lowest point – 2.41 meters below mean sea level – located in Kristianstad and the city must therefore be protected from flooding by a barrier system and water pumps. Compared to other areas in the world, where millions of people may be affected by one single flood, it may not seem to be that kind of disaster if the wall would break and some water took its way into the city boulevards. Still, for many people living and working in Kristianstad this would be kind of a nightmare.
To prevent future flooding of the city center, the existing barriers are in the process of being reinforced and new against nearby Helge å and Hammarsjön are under construction. An extensive system of ponds and dams is also being built. These measures are urgently needed, with admirable clarity demonstrated during some dramatic days in late winter 2002, when the Hammarslund barrier were quite close to collapse.
Obviously, living in Kristianstad is living with a certain flood risk. What are the consequences if the wall would break? Is it possible to quantify the consequences?
This is the topic of the master thesis “Consequences of a flood in Kristianstad, Sweden”, in which focus is put on the impacts on important societal functions in the city in case of a flood. For 125 objects, individual water levels have been defined at which the activities must stop due to security, accessibility or other reasons. In this way, it is possible to calculate the total impact to the city related to a certain water level, caused by a barrier failure or a heavy rainfall. Among the results it is seen that up to 70% of the objects would have to close at a barrier failure and 32% at a heavy rainfall, both at a 100-year event. Most vulnerable of object categories studied is retirement homes, while freshwater boreholes belong to the least vulnerable. The study will contribute to improved capacity for rescue service, decision makers and object owners to plan and take preventive measures to eliminate or minimize serious consequences of a flood.
The flood issue in Kristianstad has been hot for ages, and one thing for sure, it has definitely not become less hot during the climate change debate. A rise of sea level will make the flood risk situation even worse. It may seem as kind of a twist of fate; that a city once built easy to defend by means of water, now has become hard to defend against – the water… (Less)
Please use this url to cite or link to this publication:
author
Sjögren, Jonas LU
supervisor
organization
course
GISM01 20171
year
type
H2 - Master's Degree (Two Years)
subject
keywords
important societal functions, Hammarslund Barrier Failure, flood consequences, flood risk analysis, physical geography, geography, Geographical Information Systems, Kristianstad
publication/series
Master Thesis in Geographical Information Science
report number
64
language
English
additional info
External supervisor: Peter Zerpe, Security Manager, Kristianstad Rescue Service
id
8901352
date added to LUP
2017-01-27 09:29:53
date last changed
2017-01-27 09:29:53
@misc{8901352,
  abstract     = {According to a recent report from the Swedish Civil Contingencies Agency, the city of Kristianstad is considered as one of the most vulnerable in Sweden regarding consequences of a flood. Being protected by a barrier system, a failure would most likely have serious impact on the city. As parts of the city are situated below sea level, a heavy rainfall may cause considerable consequences since there is no natural outlet and all water has to be pumped out. 
To quantify the consequences, the master thesis “Consequences of a flood in Kristianstad, Sweden”, focuses on important societal functions and the impacts to individual objects at different water levels. A disastrous consequence has been defined for 125 important societal objects in the city, which relates to a water level where the activities at the object must stop due to security, accessibility or other reasons. 
Consequences of a water level at elevations from -2.4 m up to +4.0 m with 0.1 m steps have been investigated and related to characteristic discharge in the river Helge å, as well as to characteristic sea water levels in the Baltic Sea. The objects chosen are all situated within the +4.0 m flood area and are identified by using the priority classes 0-4 of the Styrel project, a plan that regulates disconnection of electrical power in case of transient power shortage. 
Two key figures are used to quantify the impacts on the city; the number of affected objects related to number of total objects, and affected objects providing service to a main part of the population related to total number of objects of this category. Four scenarios have been studied that would reflect a 100-year event; three with high discharge in the river Helge å and a barrier failure, a fourth scenario with a heavy rainfall. 
A consequence of a west barrier failure is that 16% of the objects with important societal function would have to close. This includes 27% of the objects providing service to a main part of the population. The figures for a Hammarslund barrier failure is 59% and 45% respectively, and for a simultaneous failure of the two barriers 70% and 58% respectively. A 100-year precipitation would affect 32% of the objects, including 12% of the objects providing service to a main part of the population. The most vulnerable object category at a 100-year event is retirement homes, while freshwater boreholes belong to the least vulnerable. In case of a 100-year precipitation, the hospital administration is found to be in special need of protection.},
  author       = {Sjögren, Jonas},
  keyword      = {important societal functions,Hammarslund Barrier Failure,flood consequences,flood risk analysis,physical geography,geography,Geographical Information Systems,Kristianstad},
  language     = {eng},
  note         = {Student Paper},
  series       = {Master Thesis in Geographical Information Science},
  title        = {Consequences of a flood in Kristianstad, Sweden : a GIS-based analysis of impacts on important societal functions},
  year         = {2017},
}