"Land that is or may be inappropriate, regarding the residents' health and safety or the risk of flooding, erosion and accidents is great, no settlement should be planned or built. An increased awareness in planning for a future climate change develops the city's adaptability, making it less vulnerable and allows it to become a more robust society" (Halmstads översiktsplan 2030).
Considering how the world and local society is developing, Halmstad will in the near future experience temperature rise, increased rainfall and rising sea levels. For a large coastal municipality like Halmstad, it is required that the municipality adapt to these challenges and take the necessary measures in good time. The consequences can be devastating if adaptation is not done for a changed future climate.
Halmstad has two areas in the city that require further analysis, these are Tullkammarkajen and Söder. Tullkammarkajen is a planned residential area, that will be built in 2020 and Söder is an area that is largely already built. Both areas are located directly next to Nissan, which floods when the water level rises above approximately +2.0 meter above sea level(masl). Today the city can count on extreme levels of +2.5 masl and the autumnstorm Gorm (2015) advised a water level of +2.37 masl. Forecasts from SMHI indicate that the sea level will increase one meter by 2100. At the same time the recurrence times for the water level of +2.5 masl will be reduced from about 50 years to only 2 years until year 2100.
The temperature in Sweden will increase during this century and Halmstads average temperature will increase from 6-8°C to 10-14°C. The number of hot days increases from 10-15 to 50-55 days per year and heat waves during the summer will be much longer, with droughts, shortage of water and in worst case deaths as a result.
The purpose of the report was to develop policy options for reducing the risk of floods and heat waves in Halmstad. The resources in the society are limited, therefore the most cost-effective adaptation is needed. The municipality currently has no knowledge of the most profitable options for reducing the impact of floods and heat waves, hence this report aims to investigate the matter.
Method has been a flood simulation, 14 interviews, a literature review and an economic assessment by a cost-benefit analysis.
Four different policy options, which reduce the risk of flooding and heatwaves, are listed in the report and investigate if the flood measures is economically profitable. They include increased vegetation,elevation, check valve, dykes, sluice gate and pumps.
The assessment compares the benefits from the actions with the cost in an economic assessment. The analysis shows that despite high investment costs, all proposals for action are economically viable with a time horizon of 100 years.