Översvämningsmodellering av ett dagvattensystem
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Storm water management has become a more important matter as urban areas are expanding and natural areas are being exploited. As nature landscapes are being converted into hard surface areas storm water flow is affected both in terms of velocity and size. A flow increase can easily result in a flooding if the dimensions of the pipeline system are inadequate. Considering predicted upcoming climate changes, flooding’s may become more common in urban areas in the future. A storm water model can be used to investigate the flooding risk in an area. A model, however, is always a simplification of reality. The models ability to describe a real system is determined by the quality of input data and model design.
This thesis aim was to demonstrate how a combined storm water and surface flow model can be used when planning solutions for storm water management in an area subjected to exploitation and climate change. The report also intends to investigate which model parameter and what input data that gives raise to the greatest uncertainty in the model. By building a storm water model in the computer program Mike Flood, the risk of flooding in the area investigated, Västra Länna, could be examined. A sensitivity analysis was performed on the constructed model to identify sensitive input data and model parameters that may affect results due to their fluctuation.
With the method used in this study the scale and volume of a flood can be calculated at the same time as wells in which the water level reaches the ground level can be identified. Such information can be used to determine where there is a need for new storm water solutions and for estimating new dimensions. The study has shown that the use of Mike Flood is suitable in urban areas where the water infiltration is limited and the storm water system is dominated by pipelines.
The results show that exploitation and climate change may have huge impact on a storm water system designed to handle a 10-year rain. In the simulation with future climate changes the number of flooded wells increased by 30 percent, being the scenario with greatest impact on the storm water system in Västra Länna. The volume of flooding water increased 1.8 times in the exploitation scenario and 2.3 times when climate change was simulated.
Based on the sensitivity analysis performed, it could be concluded that when modeling in Mike Flood, certain parameters need to be treated with greater accuracy than others. In the hydraulic model it is important that the imperviousness area used is thoroughly investigated. The parameters in the surface flow model that need to be handled with great accuracy are flooding/drying and damping factor. The construction of ditches and CDS-rain in the model also played an important part when obtaining results concerning the flooding magnitude.
Place, publisher, year, edition, pages
2013. , 58 p.
UPTEC W, ISSN 1401-5765 ; 13006
Dagvatten, översvämningar, exploatering, Mike Flood, känslighetsanalys
IdentifiersURN: urn:nbn:se:uu:diva-207540OAI: oai:DiVA.org:uu-207540DiVA: diva2:648427
Master Programme in Environmental and Water Engineering
Larsson, Conny, Docent i meteorologiRodhe, Allan, Professor i hydrologi