Pluvial flooding originating from extreme rainfall is problematic and an increasing issue in Sweden. Higher requirements on adapting cities in urban areas to these challenges have been placed on both municipalities and the county administration. Thus, an increased need for water modelling, both in existing and planned areas have emerged. The Danish Hydrological Institute (DHI) has developed several models and tools to simulate floods and heavy rains, of which MIKE 21 is one. MIKE 21 is a dynamic model consisting of hydrological calculations in each cell, requiring modelling skills and long simulation time, but is proven to be a good and credible model. SCALGO Live, on the other hand, is a static tool simulated by raster-based algorithms and capable of giving fast results directly on the platform. However, compared to MIKE 21, SCALGO Live is not as evaluated nor is its use as widespread for simulating floods and heavy rain events. This study aims to investigate how inundation in twenty urban areas caused by cloudbursts is simulated in both programs to examine how well the result coming from SCALGO Live, is equivalent to the result from the MIKE 21-model. The comparison is made in both depth and spread using three comparative indexes, two statistical equations and one map, showing the extension of the inundation in both models. To make the models comparable, the model in MIKE 21 is made as equivalent as possible with SCALGO Live before simulation and the purpose is to investigate whether there is any type of area where the two different models are equivalent. The result shows that the flooded areas from SCALGO Live are in good agreement in most areas with the MIKE 21-model, but that the depth in the depression zones is somewhat overestimated, compared with the highest value in MIKE 21. The MIKE 21-model has a greater spread upstream, showing flowpaths if compared directly with the flooded areas from SCALGO Live, but if activating the flow accumulation tool in SCALGO Live, the differences are reduced but cannot be quantified in this study. The differences between the models increase with a higher resolution, longer flowpaths and a larger catchment, at least for the confined catchments. To conclude, SCALGO Live is best suited for smaller confined catchments where there are no long or complex flowpaths. SCALGO Live also works well at an early stage in the planning process and as a platform for combining detailed data and results. However, for the more complex areas, MIKE 21 is better suited, since various parameters can be considered.

The study has consisted of creating a place for snow storage with a connecting storm water facility. This is based on findings regarding concentrations of pollutants in Luleå's snow storages in combination with Luleå's standards for design of these storages. For Luleå Municipality, the stormwater issue is relevant as the number of floods will increase as Luleå expands. This results in a greater ratio of hard-made surfaces with increased surface runoff that create risks of flooding and property damage, something that will intensify even further with climate change. Besides this, the runoff concentration of pollutants that are transported out into recipients also increases. The study has been carried out in Luleå, via Luleå Municipality and LTU. The purpose of the study was to answer the following questions:"What concentrations of pollutants are found in Luleå's meltwater?", "What does Luleå' smanagement of snow storage look like, and why?", "Where can a snow storage be placed in Luleå to enable year-round recreation?” and "Which stormwater solution should be chosen to filter pollutants from this snow deposit?". This was answered via seven different means of gathering data: literature studies, field studies/observations, meetings/interviews & E-mail exchanges, selection of a stormwater facility, calculations, simulations, and conceptual design. Through these means, the study concluded that the concentrations of pollutants in meltwater are generally greater than in stormwater, that there are recommendations regarding the size, location and safety of Luleås snow storages, that any snow storage should preferably be located where motor traffic is not present and that its space should be usable year round with regard to recreation, and that a wetland is the most suitable facility for filtering the pollutants in the meltwater from this deposit. Overall, the results conveys that the spaces set aside for snow and meltwater treatment should enable year-round recreation, in addition to their technical functions. However, does the results show nothing in terms of management of extreme cases of rainfall nor any types flooding preventions relating to stormwater management. This paper does not provide any suggestions for a snow storage site nor a stormwater treatment facility for cities with a similar or different climate. The reason that onlyr ecreation and pollution treatment were considered is because these are the most relevant in this context, firstly since toxins are more prevalent in meltwater than in stormwater, and because recreation associated with snow is a given aspect of usage. Thus were a suitable frame of question and suitable means used to generate reasonable and acceptable results.