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Olofsson, Mats
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Publications (6 of 6) Show all publications
Berggren, K., Olofsson, M., Viklander, M., Svensson, G. & Gustafsson, A.-M. (2012). Hydraulic impacts on urban drainage systems due to changes in rainfall, caused by climatic change (ed.). Paper presented at . Journal of hydrologic engineering, 17(1), 92-98
Open this publication in new window or tab >>Hydraulic impacts on urban drainage systems due to changes in rainfall, caused by climatic change
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2012 (English)In: Journal of hydrologic engineering, ISSN 1084-0699, E-ISSN 1943-5584, Vol. 17, no 1, p. 92-98Article in journal (Refereed) Published
Abstract [en]

The changes in climate were of a growing concern in the last decade, and will be even more so in the coming years. When investigating impacts on urban drainage systems due to changes in the climate, two challenges are (1) what type of input rainfall data to use, and (2) what parameters to measure the impacts. The overall objective of this study is to investigate the hydraulic performances ofurban drainage systems related to changes in rainfall, and through these hydraulic parameters describe impacts of climate change. Input rainfall data represents today's climate, as well as three future time periods (2011-2040, 2041-2070, and 2071-2100). The hydraulic parameters used were water levels in nodes (e.g. as the number of floods, frequency and duration of floods), and pipe flow ratio. For the study area, the number of flooded nodes and the geographical distribution of floods will increase in the future, as will both the flooding frequency and the duration of floods.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-14578 (URN)10.1061/(ASCE)HE.1943-5584.0000406 (DOI)000300438500010 ()2-s2.0-84857228025 (Scopus ID)df8d3c02-14a0-4ff4-8554-b1e9d3fda3b0 (Local ID)df8d3c02-14a0-4ff4-8554-b1e9d3fda3b0 (Archive number)df8d3c02-14a0-4ff4-8554-b1e9d3fda3b0 (OAI)
Note
Validerad; 2012; 20111110 (karober)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Olsson, J., Berggren, K., Olofsson, M. & Viklander, M. (2009). Applying climate model precipitation scenarios for urban hydrological assessment: a case study in Kalmar City, Sweden (ed.). Paper presented at . Atmospheric research, 62(3), 364-375
Open this publication in new window or tab >>Applying climate model precipitation scenarios for urban hydrological assessment: a case study in Kalmar City, Sweden
2009 (English)In: Atmospheric research, ISSN 0169-8095, E-ISSN 1873-2895, Vol. 62, no 3, p. 364-375Article in journal (Refereed) Published
Abstract [en]

There is growing interest in the impact of climate change on urban hydrological processes. Such assessment may be based on the precipitation output from climate models. To date, the model resolution in both time and space has been too low for proper assessment, but at least in time the resolution of available model output is approaching urban scales. In this paper, 30-min precipitation from a model grid box covering Kalmar City, Sweden, is compared with high-resolution (tipping-bucket) observations from a gauge in Kalmar. The model is found to overestimate the frequency of low rainfall intensities, and therefore the total volume, but reasonably well reproduce the highest intensities. Adapting climate model data to urban drainage applications can be done in several ways but a popular way is the so-called Delta Change (DC) method. In this method, relative changes in rainfall characteristics estimated from climate model output are transferred to an observed rainfall time series, generally by multiplicative factors. In this paper, a version of the method is proposed in which these DC factors (DCFs) are related to the rainfall intensity level. This is achieved by calculating changes in the probability distribution of rainfall intensities and modelling the DCFs as a function of percentile. Applying this method in Kalmar indicated that in summer and autumn, high intensities will increase by 20-60% by year 2100, whereas low intensities remain stable or decrease. In winter and spring, generally all intensity levels increase similarly. The results were transferred to the observed time series by varying the volume of the tipping bucket to reflect the estimated intensity changes on a 30-min time scale. In an evaluation of the transformed data at a higher 5-min resolution, effects on the intensity distribution as well as single precipitation events were demonstrated. In particular, qualitatively different changes in peak intensity and total volume are attainable, which is required in light of expected future changes of the precipitation process and a step forward as compared with simpler DC approaches. Using the DC transformed data as input in urban drainage simulations for a catchment in Kalmar indicated an increase of the number of surface floods by 20-45% during this century.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-4203 (URN)10.1016/j.atmosres.2009.01.015 (DOI)000265464600009 ()2-s2.0-62849089882 (Scopus ID)21db5fc0-08c8-11de-9f31-000ea68e967b (Local ID)21db5fc0-08c8-11de-9f31-000ea68e967b (Archive number)21db5fc0-08c8-11de-9f31-000ea68e967b (OAI)
Note
Validerad; 2009; 20090304 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Olofsson, M. (2007). Climate change and urban drainage: future precipitation and hydraulic impact (ed.). (Licentiate dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Climate change and urban drainage: future precipitation and hydraulic impact
2007 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Increasing global mean temperature influences the hydrologic cycle. In the 21st century, hydrologic change featuring more heavy precipitation events is very likely according to the UN Intergovernmental Panel on Climate Change, IPCC. This change will have a great impact on urban environments and infrastructures. In Sweden, precipitation during the winter will most likely increase by as much as 30 to 50 % by the end of the 21st century, while summer precipitation will decrease in the southern and middle parts of Sweden. Recent years have seen a number of floods caused by heavy rainfalls. With climate change, the problem with floods can be expected to continue and increase. To prevent adverse damage, modelling how the changes in precipitation and temperature will influence the urban drainage systems and how measures can be taken to prevent or reduce the consequences of floods has become increasingly important. The main objective with this thesis is to investigate the hydraulic impact in an urban drainage system due to the presumed increase in intense rainfalls. Regional Climate models produce temperature and precipitation data for the future. The regional climate model RCA3 from Rossby Center at SMHI, produces data with a spatial resolution of 50*50 km and a temporal resolution of 30 min. To be able to use the climate data in urban drainage models, temporal and spatial resolution must be improved. A modification of the so-called Delta change method, where the changes are related to the rainfall intensity level, is presented to transfer the changes in rain characteristics from different future time periods to an observed series. For the study area, the climate model shows an increase of the highest intensities of up to 20 % for the 21st century. Effects of these changes are studied on an urban drainage system in the study area. Results from the urban drainage simulations show that higher water flow- ratios in pipes, longer durations of floods, and more frequent floods can be expected if the climate continues to change with more high intensity rains, as the climate models predict. The maximum water levels in nodes were significantly higher for all future time periods that were simulated. Even in the near future (2011-2040), maximum water levels in nodes were >0,1 m higher compared to today's climate. Since the renewal rate of pipes in the existing urban drainage system is relatively slow, emphasis must not lie only on city development but also on future climate change. Design criteria, therefore, need to be changed according to changes in precipitation. Weak spots in the system must be identified for the adaptation to be as effective as possible. Knowing when, where, and how to put the correct measures when adapting the urban drainage system is essential for efficient management. Climate change also affects urban drainage in different ways, depending on where in Sweden the city lies. In northern Sweden, problems can arise with changing snowmelt patterns, for example. Further research involves an analysis of the consequences that higher water levels, increased max flow, and higher seasonal variations will have and of the adaptation strategies required not only for the urban drainage systems but also for other infrastructures.

Abstract [sv]

En ökad global medeltemperatur påverkar den hydrologiska cykeln och enligt FNs klimatpanel, IPCC, är det väldigt troligt att detta leder till fler häftiga regn under 2000-talet. Förändringen i nederbörd får stor inverkan på den urbana miljön och infrastrukturen. I Sverige ökar nederbörden vintertid med så mycket som 30-50 % i slutet av 2000-talet medan sommarnederbörden minskar i mitten och södra delarna av Sverige. De senaste åren har uppvisat ett antal översvämningar orsakade av häftiga regn. Med klimatförändringen kommer troligtvis problemen med översvämningar fortsätta att öka. Därmed har det blivit ännu viktigare att modellera hur förändringar i nederbörden påverkar det urbana dagvattensystemen och vilka åtgärder som kan sättas in för att förhindra allvarliga översvämningar och skador i framtiden. Huvudsyftet med den här avhandlingen är att undersöka vilken hydraulisk effekt den förändrade nederbörden har på urbana dagvattensystem. Regionala klimatmodeller simulerar bland annat framtida temperatur och nederbördsdata. Den regionala klimatmodellen RCA3 från Rossby Centre på SMHI, producerar data med en spatial upplösning av 50*50 km och en tidsupplösning av 30 min. För att kunna använda klimatdata i en urban dagvattenmodell måste den spatiala och tidsmässiga upplösningen förbättras. En modifiering av den så kallade Delta Change-metoden, där förändringarna är relaterade till intensiteten i nederbörden presenteras för att överföra förändringar i framtida regnkarakteristika till en uppmätt regntidsserie. För försöksplatsen visar klimatmodellen en ökning av de högsta intensiteterna med upp till 20 % under 2000-talet. Vilka hydrauliska effekter denna förändring ger upphov till studeras i en modell av ett urbant dagvattensystem från en försöksplats i södra Sverige. Resultaten från simuleringarna visar att större vattenflöde i ledningarna, längre varaktighet vid översvämningar och mer frekventa översvämningar kan förväntas om klimatet fortsätter att förändras i linje med vad klimatmodellerna förutspår. Vattennivåerna i brunnarna var signifikant högre för alla tidsperioder som simulerades. Även i den närmsta perioden (2011-2040) blir den maximala vattennivån i brunnarna 0,1 m högre jämfört med dagens klimat. Eftersom förnyelsetakten för ledningsnäten är relativt långsam så bör man inte bara titta på stads- och befolkningsutvecklingen utan även förändringar i klimatet när åtgärder planeras. Att veta när, var och hur åtgärder ska sättas in för att anpassa systemet är viktigt för en effektiv förvaltning av ledningsnäten. Svaga länkar i systemen måste identifieras för att anpassningen ska bli så effektiv som möjligt. Dimensioneringskriterier behöver ändras i linje med förändringar i nederbörden. Klimatförändringen påverkar också den urbana dräneringen på olika sätt beroende var i Sverige som staden ligger. I norra Sverige kan exempelvis problem uppkomma med förändrade mönster för snöbildning och snösmältning. Mer forskning behövs för att analysera vilka konsekvenser högre vattennivåer, högre flöden och större säsongsvariation får samt vilka anpassningsstrategier som behövs inte bara för det urbana dagvattensystemet utan även för övrig infrastruktur.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2007. p. 24
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757 ; 1997:20
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-16817 (URN)02a7f510-e73b-11db-8a98-000ea68e967b (Local ID)02a7f510-e73b-11db-8a98-000ea68e967b (Archive number)02a7f510-e73b-11db-8a98-000ea68e967b (OAI)
Note
Godkänd; 2007; 20070410 (ysko)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Berggren, K., Olofsson, M., Viklander, M. & Svensson, G. (2007). Tools for measuring climate change impacts on urban drainage systems (ed.). In: (Ed.), (Ed.), Techniques et stratégies durables pour la gestion des eaux urbaines par temps de pluie: NOVATECH 2007 ; 6e conférence internationale, juin 2007, Lyon, France. Paper presented at NOVATECH 2007 : 24/06/2007 - 29/06/2007 (pp. 239-246). Villeurbanne: Graie, 1
Open this publication in new window or tab >>Tools for measuring climate change impacts on urban drainage systems
2007 (English)In: Techniques et stratégies durables pour la gestion des eaux urbaines par temps de pluie: NOVATECH 2007 ; 6e conférence internationale, juin 2007, Lyon, France, Villeurbanne: Graie , 2007, Vol. 1, p. 239-246Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Villeurbanne: Graie, 2007
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-37804 (URN)bee9c6b0-6a97-11dc-9e58-000ea68e967b (Local ID)2-9509337-7-7 (ISBN)bee9c6b0-6a97-11dc-9e58-000ea68e967b (Archive number)bee9c6b0-6a97-11dc-9e58-000ea68e967b (OAI)
Conference
NOVATECH 2007 : 24/06/2007 - 29/06/2007
Note
Godkänd; 2007; Bibliografisk uppgift: Les outils de mesure des effets du changement climatique sur les systèmes d'assainissement pluvial urbain; 20070924 (karober)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Olofsson, M., Olsson, J., Berggren, K. & Viklander, M. (2006). Adaptation of RCA3 climate model data for the specific needs of urban hydrology simulations (ed.). In: (Ed.), Peter Molnar (Ed.), Extreme Precipitation, Multisource Data Measurement and Uncertainty: Proceedings of the 7th International workshop on precipitation in urban areas. Paper presented at International Workshop on Precipitation in Urban Areas : 07/12/2006 - 10/12/2006 (pp. 144-148). Zürich: Institute of Environmental Engineering, ETH, Zürich
Open this publication in new window or tab >>Adaptation of RCA3 climate model data for the specific needs of urban hydrology simulations
2006 (English)In: Extreme Precipitation, Multisource Data Measurement and Uncertainty: Proceedings of the 7th International workshop on precipitation in urban areas / [ed] Peter Molnar, Zürich: Institute of Environmental Engineering, ETH, Zürich , 2006, p. 144-148Conference paper, Published paper (Refereed)
Abstract [en]

Adapting climate model data to urban drainage applications can be done in several ways but a popular way is the so-called ‘delta change' method. In this method, relative changes in rainfall characteristics estimated from climate model output are transferred to an observed rainfall time series, generally by multiplicative factors. In this paper, a version of the method is proposed in which these ‘delta factors' are related to the rainfall intensity level. This is achieved by calculating changes in the probability distribution of rainfall intensities and modelling the delta factors as a function of percentile. The model is applied to 30-min output from the RCA3 regional atmospheric climate model, in a grid box covering Kalmar City, Sweden. The climate model results indicate an increase of the highest intensities by up to ~20% and a decrease of lower intensities by up to almost 40%. This result is valid for a 30-min time scale, and to evaluate whether urban drainage impact assessment can be meaningfully performed on this time scale, a MOUSE model was applied in Kalmar using different time steps. The results indicate that a 30-min time step may be meaningful, but that ways to transfer the rainfall changes also to data of a higher time resolution needs to be considered. This will be done in future studies, as well as further testing and evaluation for other Swedish cities.

Place, publisher, year, edition, pages
Zürich: Institute of Environmental Engineering, ETH, Zürich, 2006
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-39575 (URN)e639afe0-c264-11db-9ea3-000ea68e967b (Local ID)3-909386-65-2 (ISBN)e639afe0-c264-11db-9ea3-000ea68e967b (Archive number)e639afe0-c264-11db-9ea3-000ea68e967b (OAI)
Conference
International Workshop on Precipitation in Urban Areas : 07/12/2006 - 10/12/2006
Note

Godkänd; 2006; 20061212 (matol)

Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2017-11-25Bibliographically approved
Olofsson, M. & Östman, A. (2006). Optimizing dynamic network configurations (ed.). In: (Ed.), (Ed.), Proceedings of the 9th AGILE Conference on Geographic Information Science: . Paper presented at AGILE International Conference on Geographic Information Science : 20/04/2006 - 22/04/2006 (pp. 247-254).
Open this publication in new window or tab >>Optimizing dynamic network configurations
2006 (English)In: Proceedings of the 9th AGILE Conference on Geographic Information Science, 2006, p. 247-254Conference paper, Published paper (Other academic)
National Category
Architectural Engineering
Research subject
Architecture
Identifiers
urn:nbn:se:ltu:diva-35488 (URN)a08bd420-c267-11db-9ea3-000ea68e967b (Local ID)a08bd420-c267-11db-9ea3-000ea68e967b (Archive number)a08bd420-c267-11db-9ea3-000ea68e967b (OAI)
Conference
AGILE International Conference on Geographic Information Science : 20/04/2006 - 22/04/2006
Note
Godkänd; 2006; 20061212 (matol)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
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