First article published

My first article was recently published in the journal Water. I wrote this article together with 12 co-authors in our research project Sustainable Urban Flood Management (SUrF) and it gave me new insights in our different fields of research. We represent nine different affiliations and my job was to coordinate the writing process and of course to write my own parts. It is wonderful to work with this group of researchers. Thanks to all of you for your contributions!

Article: Sörensen, Johanna, et al. “Re-Thinking Urban Flood Management—Time for a Regime Shift.” Water 8.8 (2016): 332.

The article can be found here: http://dx.doi.org/10.3390/w8080332. The article is freely available online.

Abstract

Urban flooding is of growing concern due to increasing densification of urban areas, changes in land use, and climate change. The traditional engineering approach to flooding is designing single-purpose drainage systems, dams, and levees. These methods, however, are known to increase the long-term flood risk and harm the riverine ecosystems in urban as well as rural areas. In the present paper, we depart from resilience theory and suggest a concept to improve urban flood resilience. We identify areas where contemporary challenges call for improved collaborative urban flood management. The concept emphasizes resiliency and achieved synergy between increased capacity to handle stormwater runoff and improved experiential and functional quality of the urban environments. We identify research needs as well as experiments for improved sustainable and resilient stormwater management namely, flexibility of stormwater systems, energy use reduction, efficient land use, priority of transport and socioeconomic nexus, climate change impact, securing critical infrastructure, and resolving questions regarding responsibilities.

Flooding in Copenhagen 31st of August 2014 – Taxi

 

 

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Paper about severe floods in Malmö

Finally, I have finished my paper about severe floods in Malmö. It is a detailed, qualitative studie of the three most severe flood events –5th of July 2007, 14th of August 2010, and 31st of August 2014– and a comparison with smaller floods, where I have look closer at the causality behind flooding. Now I am eager to continue with statistical analysis of the same data set. I will work together with department of mathematical statistics. With their help, I will hopefully increase my knowledge in the field of extreme values modelling, and they are in constant need of interesting data sets – what a good base for collaboration!

paper_finished2

Finished paper together with some of the references.

 

One year since the severe flood in Malmö and Copenhagen 2014

Flooding in Copenhagen 31st of August 2014It is today one year since Malmö (Sweden) and Copenhagen (Denmark) were severely flooded on the 31st of August 2014. Copenhagen has already been challenged by floods in 2010 and 2011, while the severity of this flood event was new to Malmö and south-western Scania. The flood has been like a wake-up call for southern Sweden when it comes to how fragile the modern society are to severe stress like from this flood.

Flooding in Copenhagen 31st of August 2014 – destroyed manhole One year later, this flood event still effects the city: several house owners have not been able to move back yet (!), a group of employees at the utility company VA Syd are working full time to assess all flood reports from the citizens, at the university we will in few weeks start a big project on urban flood resilience, and Malmö municipality will write their first cloud-burst plan. I write on an article about the flood event in Malmö, where I look into how the city was affected. I compare this flood event with the much smaller, but still severe, flood events in 2007 and 2010, and discuss how we can learn from these flood events in the future city planning. Hopefully, I will submit the article to an international journal in October or November.

The local newspaper, Sydsvenskan, writes today about the flood event (in Swedish): Ett år efter översvämningarna i Malmö. They have also collected video clips from the event: Se videoklipp från regnkaoset.

Before and after – it takes a flood to understand

Pluvial flood in Copenhagen August 2014

Pluvial flood in Copenhagen August 2014

When I started my PhD study in 2012, everyone said: I see, you live in Copenhagen – over there floods are of great interest. Copenhagen was flooded in August 2010, July 2011 and once more in August 2011. My PhD topic (urban flooding in a changing climate) was of course partly inspired by these three floods, but also by the need to create better cities in the future. We need greener cities and more resilient stormwater systems. This was in 2012 and the interest of flooding in Sweden was rather weak.

Then, in 2014, the rain fell. After a few hours of heavy rainfall, floods where suddenly on everyone lips. Malmö was hit by a costly and frightening flood event. Now people had their own experience of what a flood could be. It is not any longer a problem “over there”, in Copenhagen. It takes only 35 minutes to go from central Copenhagen to Malmö. Nevertheless, it took the flood risk awareness more than three years to cross the bridge.

Cars flooded in Copenhagen 2014

Cars flooded in Copenhagen 2014

Gothenburg have seen similar flood events and they seem to be aware of the problem. During a conference in Gothenburg, someone discussed why the national authorities in Sweden still seems so unaware of the pluvial flood risk. As this person mentioned: “We have still not seen a major flood event in a bigger Swedish city – read: Stockholm!” I guess this summarises the problem with risk awareness. It is unbelievable hard to understand the risk of flooding before you have seen one yourself in your own town.

Floods in Malmö, Sweden

On the 31st of august, heavy rainfall hit Malmö in southern Sweden. The city has never before seen such volumes of water in the streets, basements and backyards – at least not in modern time. At Lund University, we decided to take a closer look at the flood event. We try to understand how all the green spaces and open stormwater solutions, that Malmö city is well known for, did affect this flood event. The open stormwater systems in Malmö were not specifically designed to prevent from flooding, but this could be an important, positive side effect of the systems.

My student, Joanna Theland, have contacted the utility company (VA Syd), insurance companies and house owners in Malmö, to collect information about consequences of the flooding. Everyone have been very helpful and we have had interesting conversations with both VA Syd, Länsförsäkringar Skåne (an insurance company) and others about this flood event and flooding in general. I would say that Swedish authorities are getting more and more focused on floods and flood prevention. We are going from an idea that floods are a natural catastrophe that we only can act upon after the disaster already has happened, to a more proactive view were we see possibilities to prevent areas, important buildings, as well as our own basement from flooding. There is a great interest in our study and in how to build cities in a better way in the future.

Joanna Theland will present the results from this study in March. After this, I will continue with more analyses. One idea is to compare the situation in Malmö with other cities that have seen recent flood events. One might be Helsingborg, as my contacts there (at NSVA) have been very helpful.

The photos beneath are all from Copenhagen. The same rainfall as in Malmö, on the 31st of august 2014, stroke Copenhagen and I took a trip with my bike to document some of the consequences in the city.

Development of stormwater systems

I am very thankful to ÅForsk, who gave me the opportunity to go to the International Conference on Flood Resilience (ICFR) in Exeter, Great Britain. I am also glad that my paper about the storm water systems in Gothenburg and Mumbai got accepted to be presented at the conference. It gave me a great chance to dig deep into the development history of the stormwater system in Gothenburg. Arun Rana and I made a comparison between the Gothenburg system and the stormwater system in Mumbai and learned a lot from reading about how the systems have developed.

Stormwater inlet in street

Stormwater inlet in street

The sewer system of yesterday strongly influences the system of today and thereby also the system of tomorrow. Because stormwater and sewage structures last for a long time, and the price to reconstruct the systems are very high, the old system will have strong influence on all future decisions. Cettner, Söderholm and Viklander (2012) did write an interesting article about this in Journal of Urban Technology. This was one of the important learnings from the article writing and my conference preparation.

Conference lunch at ICFR in Exeter

Conference lunch at ICFR in Exeter
Photo: Johanna Sörensen

At the conference, I enjoyed to meet peers from all different universities, working with flood related issues in European and Asian cities. We discussed how the urbanisation and city development affect flood risk in growing cities and how climate change can aggravate the risk. We discussed how to cope with the flood risk, both from a technical and a social point of view. How far can we come with technology? What are the possibilities to protect our cities from floods? Flooding is one of the most wide-spread disasters, which can hit cities in various climates all over the world. A big concern for the future is the rising sea level, due to heating of the globe. In addition to rising sea level, we will also see more high-intense storms in many places. How can we construct our cities in a smart way to handle this? The main idea from the conference, which I took with me home, was that we will not be able to totally avoid flooding. When cities are hit by the most extreme events, there will be floods of such a magnitude that we cannot prevent them. Therefore, we need to build cities in a resilient way, with flexible systems, flexible public organisations, and flexible citizens that are prepared to cope with floods. A big flood event must not be a catastrophe for the city if the preparation is good and the technology is adaptable.

The conference gave me a complete view of ongoing flooding research. There are four main driving forces behind severe pluvial flooding in cities today: higher precipitation due to climate change, urbanisation, land use change, and higher sea level due to climate change, which can aggravate pluvial flooding. In some parts of the world, only one or the other driving force is seen, but in many places are several of these processes ongoing.

Comparison between stormwater system in Gothenburg and in Mumbai

There are several similarities between the stormwater system in Gothenburg and in Mumbai. Both systems where constructed in the late 19th century with strong influences from Great Britain. India was at the time under British control and the British engineers led important infrastructure projects in Mumbai, among those building of the early sewer system. In Gothenburg, Swedish engineers went to London to learn about the new technology and were in this way strongly influenced by the British engineers. Later on, the German engineers led the technological development in this field in Europe. Today the systems in the two cities are very different, despite the fact that the first parts where built in the same time and in the same way. After the British Empire left India, the infrastructural development of Mumbai stagnated. Things have happened since then, but at a slower pace compare to Gothenburg, were the development continued. Also the urbanisation has been considerably stronger in Mumbai, which is the biggest centre for trade and commerce in India.

Solid waste in stormwater system in Mumbai

Solid waste in stormwater system in Mumbai.

It is obvious that the problems related to flooding are much bigger in Mumbai, compared to Gothenburg. The monsoon period comes every year with heavy rainfall and the stormwater system does not have capacity enough to handle the runoff. The solid waste system in the city is not satisfactory, meaning a lot of plastic bags with solid waste lie in the watercourses instead of landfills and cause clogging of the stormwater system during the monsoon period. The municipality aims to clean all watercourses before monsoon, but often the jobs is not done careful enough to keep the watercourses free from clogging. Therefore, a better solid waste system is very important to improve flood control in Mumbai. Another problem in Mumbai is settlements on flood plains along the river. Many people in Mumbai are very poor and the city is overloaded with people. Because there is no housing for all people in Mumbai, many informal settlements are built on the floodplain and people of the floodplain lives in a high risk of flooding. As this is the poorest people in the city, they also have least possibility to protect themselves.

The ship Götheborg in Gothenburg harbour.

The ship Götheborg in Gothenburg harbour. Götheborg is a copy of a 18th century ship.
Photo: Mikael Tigerström.

One similarity between Mumbai and Gothenburg is that both cities were built on former marshland along the coast. Both cities were built as an important port and economical centre for their region. They are both low-laying and situated close to the sea, meaning the water cannot easily leave the area during storm. Gothenburg is known as one of the rainiest cities in Sweden, while Mumbai is situated in an area with monsoon climate. Both Gothenburg and Mumbai lay on the west coast with mainly westerly winds, meaning they are influenced by the sea.

Mölndal River

Mölndal River at Lackarebäcksmotet.
Photo: Johan Jonsson.

In Gothenburg the area around the central station, Gullbergsvass, is low-laying and in high risk of getting flooded. There are far-reaching plans to develop this area into a housing and shopping area in the future, despite the high flood risk from Mölndal River. When it comes to flooding, this is one of the main problems in Gothenburg, together with rising sea level and landslides along Göta River. When reading about this, I learned that high risk of flooding not always is enough argument to leave an area free from expensive investments.

 Reference

Cettner, A., Söderholm, K., and Viklander, M. (2012) An Adaptive Stormwater Culture? Historical Perspectives on the Status of Stormwater within the Swedish Urban Water System. Journal of Urban Technology, 19(3), 25–40.