Tarek Zaqout defended his PhD thesis on SuDS in cold climates

Today, Tarek defended his PhD thesis: Hydrologic Performance of Sustainable Urban Drainage Systems in Cold Maritime Climates. As a co-supervisor*, I was very proud to listen to his presentation and scientific discussion with the two opponents Dr. Tone Merete Muthanna from NTNU in Norway and Dr. Ryan Winston from Ohio State University in the US. Among many interesting topics, Tone discussed the role of swales for flow control in cold climates and Ryan discussed aspects of water quality control with infiltration systems. Tarek was, as usual, well prepared and had clear thoughts and answers to all questions, including improvements of future field studies, modelling, and statistical analyses, which I find important for his future career. Congratulations, Tarek, to a very well deserved PhD and a great presentation and defence!

*The formal title I have had at University of Iceland is doctoral committee member. Main supervisor was Hrund Ólöf Andradóttir. Ólafur Gestur Arnalds was in the doctoral committee with me.

IPCC Grand Seminar

I had the great honour to be panellist of the IPCC Grand Seminar arranged today at Lund University by MERGE, BECC and LU Land. I talked about pluvial flooding and how urban areas can be adapted to climate change. With me I bring new ideas on how we can mitigate and adapt to climate change. There are three main points that I want to share from the seminar:

  • The last report from IPCC, the AR6 report on the physical science base of climate change is great. Read it! I think it is great for two reasons: 1) there conclusions are more clear than ever and 2) they have included illustrative figures that very useful in order to explain historic and future climate change, as well as the effects on a wide variety of drivers, like extreme heat, landslides, fire weather, and coastal erosion. With 35 different drivers, there is valuable information independent on your specific interest.
  • The group of climate change deniers is relatively small, about 10% in the U.S. for instance. We should therefore focus on the broad public and use our time to discuss with them.
  • And finally, it is important how we vote in national elections. The elections are one of the most important ways to influence the politics and the system that steers what measures that are taken.
Me at the IPCC Grand Seminar together with skilled researchers, including Markku Rummukainen (Swedish representative in IPCC) and Deliang Chen (one of the authors).

Dissertation on Friday


Karl helping his mother with thesis writing.

On Friday I will finally defend my thesis! I have been looking forward to this day for long time now. All summer we have lived together, me and my thesis, and it has been so much joy to write it, to search for the connection between my five articles, to shape my theoretical background in words, sentences, and paragraphs. I have always enjoyed writing in Swedish and now I have finally begun to enjoy writing in English. The final product, the thesis, has its mistakes and shortcomings, and I guess any researcher has things to add for the next study that was not included in the one before, but with the five studies I base my thesis on, I am satisfied with the final result. I hope that others, more senior researchers, in the field like it as well.

If you would like to read it, you can find it online for free or write to me and I will send you a paper copy as soon as possible. You are also welcome to come and listen to the open defense in Lund on Friday.


PhD thesis, Johanna Sörensen

PhD thesis, Johanna Sörensen, Water Resources Engineering, Lund University

Abstract This thesis investigates urban, pluvial flooding and if blue-green infrastructure, for handling of stormwater in urban green spaces, can be used as a strategy for resilient flood risk management. Spatial analyses of flood claims from insurance companies and the water utility company of Malmö are used to better understand the mechanisms and characteristics of pluvial flooding and how blue-green infrastructure impacts flood risk. It was found that flooding during intense rainfall often is located closely to the main overland flow paths and the main sewers, while flooding during rainfall with longer duration seem to be more randomly distributed. Combined sewers are more affected by flooding than separate sewers. Blue-green infrastructure can reduce urban, pluvial flooding. The large-scale spatial distribution of flooding with respect to urban flow paths and drainage system are discussed in relation to the small-scale impact of surface water detention in e.g. detention basins and concave green spaces. Based on transition theory, socio-technical transition towards wide-spread implementation of such measures are examined through interviews with municipal and water utility officials. Legal, organisational and financial changes are suggested. A framework for management of spatial data in the strategic planning of blue-green infrastructure is also presented. The thesis consists of a summary and five appended papers, where the first paper serves as a background for the thesis.

Dagvattenkonferens hos Svenskt Vatten

Svenskt Vatten samlade till konferens om dagvatten i Stockholm i veckan. Konferensen samlade avloppsingenjörer och forskare från hela Sverige. Som vanligt var det bästa med konferensen alla nya, spännande personer som jag träffade. Det är otroligt intressant att höra vad folk jobbar med i olika sammanhang, speciellt de som arbetar med mest annorlunda vinklar i förhållande till en själv. På denna konferensen mötte jag till exempel en person från ett byggföretag som arbetar med hur de ska inkorporera dagvattenhantering i byggprocessen på ett bra sätt mycket intressant. Själv presenterade jag min forskning kring vilka faktorer som påverkar översvämning vid kraftiga regn, t.ex. topografi, typ av avloppssystem, närhet till ledningsnät, lokal hantering av dagvatten, osv. Jag fick många värdefulla kommentarer från både forskare och praktiker, vilket jag uppskattar mycket. Dessutom presenterade Maria, Salar och jag forskning kring dagvattensystemet Augustenborg, där min del handlade om hur Augustenborg påverkades vid extremregnet 31 augusti 2014. Även denna presentation gav upphov till många intressanta diskussioner att ta med sig hem.

Här kan du se min presentation Vilka regn orsakar översvämning och var?

Och här kan du se min, Salar och Marias presentation Blå-gröna lösningars effektivitet i urban dagvattenhantering– erfarenheter från Augustenborg i Malmö



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.


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



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!


Finished paper together with some of the references.


London in November

Picture of prof. Čedo Maksimović on a nice walk in Karlstad, Sweden.

Prof. Čedo Maksimović on a nice walk in Karlstad, Sweden.

Professor Čedo Maksimović has nicely invited me to visit his department at Imperial College in London and in November I will finally go there. I met Čedo in the urban drainage conference in Malaysia last year and we came to talk about interesting topics concerning how we build our cities in a new and more sustainable way. Čedo is a person with many good ideas and I am looking forward to meet with him and his fellow researchers in the Urban Water Research Group. I can definitely learn a lot from these people and I hope that I also can contribute a little with ideas from my own work. Čedo and I both find it very important to integrate the urban water systems more in the city. This holistic view seems obvious, but in the same time challenging, to me. As the rain falls over the whole city, it is clear that the stormwater solutions must be integrated in the city planning for all of the urban areas. As we know from floods around the world, we cannot hide the water from the city – it is impossible. Water should be seen as a great resource. With some new thinking we can combine interest like water, energy, aesthetics, food and even joy in the same solutions and thereby win a lot.

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.

Forskning.se skriver om vår senaste rapport

Idag skrev forskning.se om vår senaste rapport: Identifiering av extrema händelser och dess översvämningskonsekvenser i tätort. Själva rapporten kan laddas hem från SVUs hemsida. Jag har bidragit med två artiklar till rapporten. Båda artiklarna är konferensartiklar och de handlar om risken för översvämningar när det både regnar mycket och havet samtidigt tränger sig på. Förrutom mina artiklar omfattar rapporten forskning som bland annat Lars Bengtsson (min doktorandhandledare), Arun Rana (vår tidigare kollega, nu disputerad och verksam på ett universitet i Portland, USA) och Karolina Berggren (disputerad från Luleå tekniska universitet) har gjort. Rapporten ger en del intressant läsning till den som intresserar sig för extrem nederbörd och hur översvämningar påverkar våra städer.

Mina artiklar

Sörensen, J., & Rana, A. (2013). Comparative Analysis of Flooding in Gothenburg, Sweden and Mumbai, India: a Review. International Conference on Flood Resilience, Experiences in Asia and Europe. Exeter.

Sörensen, J., & Bengtsson, L. (2014). Combined effects of high water level and precipitation on flooding of Gothenburg, Sweden. 13th International Conference on Urban Drainage (pp. 7–12). Sarawak, Malaysia.


Model setup finished

.bat-fil for start-up of my latest four Mike21-files.

.bat-fil for start-up of my latest four Mike21-files.

Today I have finished my model setup for the next four models – Whoa! I am feel released for all forms of stress right now. Tonight I will celebrate by doing nothing and enjoy a cup of tea together with my parents at their place.
When the model simulations are finished, in three or four days, I will spends some time to gather the results. I am looking forward to see what they can tell me. In the meanwhile I will try out another model setup I have been thinking of, start to teach my new student group in hydrology and hydraulics (introductory course) and hopefully give a seminar to my colleagues at the department.