Flood mapping — display service

Summary MSB has the government’s mission to provide the country’s municipalities and county administrative boards with an overview of areas that can be flooded along the country’s lakes and streams. The purpose of flood mapping is, among other things, to be a planning basis for municipalities’ comprehensive spatial planning and as a basis for the work on the municipal action programmes. The mappings can also be a support for the overall planning of operations by the civil protection services. The updated flood mapping replaces the data set of over-the-counter flood mappings as these are updated since 2013 with the new National Altitude Model, http://www.lantmateriet.se/sv/Kartor-och-geografisk-information/Hojddata/GSD-Hojddata-grid-2/ developed by Lantmäteriet, as well as with some flows adapted to the climate of the future at the end of the century. The updated flood maps show the water distribution at 3 different flows, the estimated highest flow rate and climate-adapted 100-year and 200-year flow for the end of the century. The return time of an event means that it occurs or is exceeded on average once during this time. This means that the probability of a 100-year flow is 1 in 100 for each year. The probability of the flow occurring once in the 100-year period is 63 percent and the probability of it occurring twice in the same period is 40 percent.