![]() ![]() The flood map service also includes maps of dam damage surveys and previous floods. “When we compared different material, we discovered that the differences in the number of buildings located in flood areas between these two registers are smaller than we expected”, Huokuna says. The number of people and buildings was evaluated using the building and apartment register, which has been supplemented using building data included in the National Topographic Database. In addition, flood risk maps present the number of people living in the flood area, roads remaining under water and special areas, such as treatment and educational institutions, waste processing sites and culturally and historically valuable sites. “We were able to prepare flood maps fairly easily for more return periods than what is required in the Floods Directive”, says Mikko Huokuna from SYKE.įlood hazard maps present the coverage and depth of floods. Flood maps have been prepared for floods occurring once in 5, 10, 20, 50, 100, 250 and 1,000 years. Return period 1/5a means that the water level rises to the flood height once in five years on average. Finland’s environmental administration is in charge of flood scenarios regarding rivers and FMI is responsible for those regarding sea areas.įlood hazards are indicated by different probabilities of floods. ![]() In 2017, SYKE and the Finnish Meteorological Institute (FMI) prepared a flood map for Finland’s coastal areas. Flood models were calculated using this data and the probabilities of floods were determined on the basis of data material.įlood maps have been prepared for areas where inland flooding is more likely to occur. Observations of water levels and flows have been used to calibrate the model. The flood maps prepared by ELY Centres are based on the National Land Survey’s DEM2 elevation model and numerical flow models based on cross-sections of channels. An elevation model offers key information The previous recommendations dated back to 1998. The lowest recommended building levels were updated in 2014. For example, residential buildings should be located at least so high that an overflow of water can reach the area only once in a hundred years on average. The maps not only help to prevent flood damage and to improve communication, they also offer support in land use planning. The flood maps indicate what areas are at risk during floods of different magnitudes. These flood maps are available in the flood map service maintained by the Finnish Environment Institute (SYKE). On the basis of flood maps, ELY Centres prepare management plans for flood risks. In addition to these, flood maps have been prepared for roughly 120 areas by the end of 2018. During the first six-year period, closed at the end of 2015, Centres for Economic Development, Transport and the Environment (ELY Centres) prepared flood hazard and floor risk maps for 21 significant risk areas. The EU Floods Directive speeded up flood mapping in Finland. The modelling system is refined as the raw data becomes more detailed and information about the impact of climate change increases. Text: Katri Isotalo, updated by Mikko Huokuna, Mikko Sane and Antti Parjanneįlood maps show how likely it is that an area remains under water when there is a flood. ![]()
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