named after N. Zhukovsky «Kharkov Aviation Institute» UKRAINE During the year, there are significant rises in the rivers associated with flooding and high water. A rapid rise in water level causes flooding of large areas, usually within the floodplain. This leads to submergence of households, destruction of crops and human casualties. Pollution caused by industrial enterprises, sewage treatment plants, etc. can also enter the flood zone. The use of GIS technologies, which is a universal tool

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... comprehensive remote sensing data processing and contact research, allows with the least material and time costs to build cartographic models of probable flooding areas [1]. Determination of probable flood zones should be performed in the ArcGIS environment with the 3DAnalyst tool based on the usage of both -contact and remote sensing data. In order to reduce time costs, to determine the boundaries of flooding, it is rational to use automatic geometric modeling. Simulation of flooding was performed by comparing the sloping water level and the height of the terrain [2]. Then, according to certain rules, polygons of flood zones are formed, flood depths are determined. To do this, across certain distances along the river valley, transverse ridges are built, where the maximum mark of rising water level in the river (Z) is indicated. Data on the water level rise process were obtained on the website of the Ukrainian Hydrometeorological Center [3], as well as from literature sources [4] . Next, on the basis of mentioned profiles, a TIN model of the water surface is built [5]. Using the "SurfaceDifference" geoprocessing tool, two data sets are built: 1) a vector layer with 3 classes of objects: "flooded", "not flooded" and "on the same level"; 2) raster surface of the flooding depths. As an input data for constructing these models, a digital terrain model SRTM [6] , or a DEM model obtained from aerial photography and a TIN model of the water surface could be used. The "SurfaceDifference" geoprocessing tool works as follows: the values of the triangles k of the TIN model of the water surface are compared with the values of the corresponding triangle k of the digital terrain model ℎ and as a result, determined by the formula (1), three classes of values in the corresponding triangle are obtained: -1 -"flooded"; 0 -"on one level"; 1 -"flooded" (Floodplain delineation from lidar points) [5] .