The river runoff regime significantly changed worldwide in the end of XX – the beginning of XXI century. In the European part of Russia the current changes are manifested in different ways in various regions. The main trend that is observed for most river basins is the ‘leveling’ of annual hydrographs. The interception of melt water during occasional thaw floods has resulted in a decrease in river runoff during the spring months. Simultaneously an increase in the low water period during winter and summer occurred. Reducing in the depth of soil freezing, caused by warm winters, lead to higher groundwater replenishment. At the same time, the loss of melt water to surface retention as well as evaporation has increased. Almost in all seasons of the year the number of occasional flood peaks increases. Occasional floods are superimposed both on the rise and the decline of seasonal snowmelt flood wave, making it difficult to separate it as an independent phase of the water regime. Changes in seasonal characteristics of river runoff are the most evident in the Don and Oka basins. A significant transformation of the water regime is observed in the north-west of European Russia as well. To a lesser extent, the described patterns are typical for the northern rivers and the eastern part of the European Russia – the Kama and the Ural Basin.

Occasional Floods On The Rivers Of Russian Plain In The 20 Th –21 St Centuries

Water regime of rivers is an important characteristic of the surface land waters as a natural environment component and object of economic use. The reaction of the rivers’ water regime to the climatic changes, including the case of extreme hydro-meteorological events, has not been studied carefully yet. It is necessary to adapt the water part of national economy to the current trends and characteristics of rivers’ water and ice regime. The analysis and inventory of these trends are required to make appropriate decisions. The authors present the methodology and the results of mapping the current European Russia rivers’ water regime and its modern transformation. The resulting map series includes the maps of the season beginning months, the coefficient of natural flow regulation, the average runoff depth for the "historical" period, extreme monthly equal discharge rate, the ratio of average monthly discharge between seasons, the runoff depth in the "modern" period and its change compared to the "historical" one, a map of water regime transformation, as well as a number of supplementary climatic maps reflecting changes in temperature and precipitation regime. The obtained maps allowed revealing numerous spatiotemporal tendencies, including intensification of the hydrological cycle; the increase in the annual runoff depth in the middle of the East European Plain; increase of absolute unevenness of summer low-water runoff and decrease of relative unevenness; the decrease of maximum discharge; significant change of the ratio of discharge components for the most rivers of the European Russia, the most important feature of which is decreasing the share of snowmelting component.

The paper considers GIS software which may be utilized for airborne lidar data processing. Software list includes proprietary MicroStation with TerraScan plugin, Global Mapper, ArcGIS, ERDAS Imagine, LAStools, as well as free and open source SAGA, WhiteboxTools, and PDAL.io. Possibilities of import-export, 2D and 3D data visualization, point cloud editing and derivation of GIS datasets are examined for each software. Computational efficiency assessment is performed for the procedure of interpolation point elevation data in different software. As a result, the advantages and disadvantages of the considered programs were identified in relation to various tasks. Key words: airborne laser scanning, software, geoinformation mapping, computational efficiency.