Flooding of Mälaren

The flooding of Mälaren is developed within the government mission, Consequences of a flooding in Mälaren, Fö2010/560/SSK. The mission was to analyse and assess the impact of a flooding in Mälaren on different sectors of society. In order to carry out the mandate, a number of analytical methods have been used. In particular, many GIS analyses have been carried out on the basis of flooding of Mälaren. The flooding of Mälaren refers only to Mälaren, not flowing water courses, etc. In that map, Mälaren was regarded as a ‘flat’ lake. No hydraulic model has been created. The mapping shows the distribution of the Mälaren from the mean water level, + 0.9 m in RH2000, and for each decimeter interval up to the theoretical maximum level, + 3.1 m in RH2000. The mapping is based on the National Altitude Model, http://www.lantmateriet.se/sv/Kartor-och-geografisk-information/Hojddata/GSD-Hojddata-grid-2/, developed by the Lantmäteriet. In addition to the distribution of water at different water levels, flood management also contains data allowing the development of water depths at different water levels as well as information on potentially enclosed areas at different water levels. Potentially enclosed areas are defined as areas below the Mälarna water surface but which, according to the altitude model, are not in direct contact with Mälaren. These are areas within a grassland, for example.