Search for: [Abstract = "Determination of flood risk includes the element of exposure to flood damage. Proper siting of the important infrastructure of a city should take account of the factor that is danger of flooding. The case study of the City of Warsaw has been used to illustrate a new method for determining levels of exposure to flooding posed by the River Vistula. On the basis of retro\-modelling, maximum possible flood discharge is a calculated Q=8250 m3s–1. In turn, from the graph of the flood potential index by Françou, the value is 9500 m3s–1. The Vistula Valley within Warsaw City is constrained by flood protective dikes and boulevards forming the so\-called “Warsaw corset”. The spacing of dikes and boulevards in Warsaw is only 470\-480 m, at the point some 511\-514 km along the River Vistula. The maximum range of potential flooding has been estimated by merging two maps, of which one presents a preliminary estimation of the flood risk as prepared in accordance with the EU Flood Directive, while the other is a map of potential flooding elaborated on the basis of the detailed geological map of Poland. The level reached by the kind of flood only recurring every 100 years was presented in the form of contour lines covering the city’s potentially flooded area. By way of linear interpolation, a flood surface model was calculated – to a raster format of 5 m resolution. The digital terrain model of the City of Warsaw and Vistula Valley, as well as the geometry of buildings were obtained from the Geodetic Department of the City authority. Using logical operators the depth of inundation of buildings was calculated, along with inundation and the volume of inundated buildings in the scenario of potential flooding only recurring every 100 years. The maximum depth of inundation is 7.2 m. The extent of inundation of buildings is subject to a classification into\: class 0 – no inundation – 0 points\; class 1 – inundation depth 0 – 0.5 m – 10 points\; class 2 – inundation depth 0.5 – 2.0 m – 20 points\; class 3 – inundation depths of 2.0 – 4.0 m – 25 points\; class 4 – inundation depth exceeding 4.0 m – 30 points. The volume of inundated buildings varies from 0 to above 90.000 m3. This range has been divided into 10 classes by reference to a percentile division. The obtained classes have been aggregated to 100 m grid data and presented in the context of the map of exposure to flood severe enough to recur only every 100 years. The method presented can be used in estimating both exposition and flood risk. The relevant data are easily available and GIS analysis represents a standard spatial data processing method. The results obtained here fall within the framework of a bigger Life_Adaptcity_pl project entitled “Preparation of a strategy of adaptation to climate change with use of city climate mapping and public participation”."]

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