Cities, rain & risk

Cities, rain & risk

Today our large project on sustainable urban flood management (SuRF) is presented at a conference in Malmö. We learn about reasons for flooding and what we can do about it.

Jens Thoms Ivarsson from Gothenburg started out by stating that Gothenburg aims to be the best city in the world when it rains. He gave an inspiring speech about art and rain – a very good start for a conference like this. I look forward to present my research tomorrow. Then I will speak about two studies from my thesis and hopefully get feedback on my last study on rain and flooding.

 

Dissertation on Friday

Karl_writing

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.

Pris från Föreningen Vatten

Igår fick jag New Generation-priset från Föreningen Vatten. Jag är mäkta stolt!

“Priset skall delas ut till en yngre person eller grupp av personer, verksamma i Sverige, som genom hög kompetens, engagemang, initiativkraft, nytänkande och framåtanda bidrar till en sund och hållbar utveckling inom vattenområdet.”

Efter prisutdelningen höll jag föredrag om hållbar hantering av översvämningar. Jag presenterade min forskning från Malmö där jag tittat på vilka mekanismer som styr var översvämningen drabbar spatialt. Dessutom pratade jag om vad som kan göras med blå-gröna lösningar för att minska risken för översvämningar. Det senare har jag studerat i Ekostaden Augustenborg där det finns ett utvecklat system för hållbar dagvattenhantering med dammar, kanaler, svackdiken och gröna tak.

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.

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

 

 

Hard for small municipalities to adapt

It seems like the process adaptation to climate change is slower in Sweden, compared to Denmark. My experience is that Danish municipalities have worked more intensively with climate change adaptation during the last decade. There might be many reasons for this, but one cause that I have discussed with my engineering colleagues is that Swedish municipalities in general are much smaller than Danish municipalities.

Comparison

Histogram of population is Swedish and Danish municipalities

To clarify the difference between the size of Danish and Swedish municipalities, I made a histogram that illustrates the size of population. While most Danish municipalities have a population of between 30.000 and 70.000, most Swedish municipalities are smaller than 20.000. These municipalities have a hard time to make sure that they have the right competence for such a difficult task as climate change adaptation. Expertise is needed that can include the perspective of far-distant, future development in master plans for urban areas. One possible solution for Sweden to ensure even stronger coordination between neighbouring municipalities. This is however a demanding task in the already overstretched organisations.

Danish data comes from Danmarks statistik and Swedish data comes from Statistiska centralbyrån, SCB. Data from end of 2014/beginning of 2015.

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.