Purpose: In many cities there are areas that are lower than the surrounding terrain (low-lying areas). In these low-lying areas, there is a great risk that stormwater will accumu-late in the event of heavy rainfall and cause floods and damage to buildings and facili-ties. In this study, a review has been carried out of various theories, methods and appli-cations that can form the basis for a technical solution to solve the problem of flood risk in an urban environment with low-lying areas.
Method: First, a literature study was conducted to, among other things, deepen the knowledge of the subject. Subsequently, four interviews were conducted where the goal was to utilize the knowledge that experts have about which technical solutions are suit-able in an urban environment and what costs different stormwater facilities have. The last step was to carry out a case study where a selected solution was studied with the aim of investigating the suitability of constructing that solution.
Findings: The interviews showed that there are many parameters to take into account when designing and building stormwater facilities that are effective in the event of a downpour. Open solutions such as flood surfaces and ditches / canals were preferred as they were partly more efficient and partly because they were often cheaper to construct. The literature study also gave similar results, but there was greater variation in which solutions were suitable. The case study showed that the proposed solution could swal-low up to 60% of the precipitation in a 30-year rain but in the worst case only 16% of a 100-year rain.
Implications: Judging by the results, the proposed solution was not sufficient to solve the flood problem in the event of a 100-year rain, which was the return time that Växjö municipality has the biggest problem with. To handle the large amount of precipitation, very large magazine volumes or many small solutions are needed in order for an ac-cepted level to be achieved, which the solution that was tested could not achieve. In the interviews, it also emerged that this was often the problem, which is basically due to too little available space and too much hardened surface. The recommendation will be to supplement with several other solutions or to install so-called cassettes under the street to increase storage capacity.
Limitations: The result is limited by the fact that it is site-specific and thus more diffi-cult to apply in other locations. Since interviews have been conducted in several differ-ent municipalities, however, this aspect has diminished somewhat as many different opinions have been noted and presented. The calculations performed were not through a data modelling, which could possibly affect the reliability somewhat, even though according to the literature it was considered to maintain a sufficient level to be able to be used on smaller areas.