Halochkin M. Theoretical principles and methods of hydrological modeling of flood zones using remote sensing materials and geographic information systems

Flooding is a frequently recurring and threatening natural disaster that occurs in the world and which leads to significant material and social losses. Over the past decades, the world has developed a methodology for modeling flood zones and predicting the threat of destruction in order to minimize losses, prevent the tragic consequences of these phenomena and promptly inform the population. In modern technologies, such modeling requires the study of morphometric and hydrological features of river channels and is based on the use of remote sensing data, geographic information systems and special hydrological modules. In Section 1, the main causes of channel processes that have both natural and anthropogenic origin are considered. The causes of changes in channel processes, natural and anthropogenic factors that affect them, as well as their active and passive forms of manifestation are considered. The analysis of literature sources concerns both the theoretical foundations of hydrological modeling and practical application of the developed methods for assessing the area of flooded land due to flood events. In Section 2, the classification of models for hydrological modeling of flooded areas, criteria for their application depending on operational hydrological and morphometric data is considered. The main characteristics of the models and their application are presented. Particular attention is paid to the analysis of the theoretical foundations of the Saint-Venant equations based on the laws of conservation of momentum and mass of fluid, which are used to solve applied problems of unsteady fluid motion in open channels. 7 Studies have confirmed that the accuracy of predicted water levels and maximum water depths simulated by the Saint-Venant model depends on an accurate representation of the channel geometry, channel level and bank slopes along the river. In Section 3, the essence of the experimental work concerning the hydrological modeling of flooded lands for two different hill and morphometric characteristics of the Dniester riverbed sections: the plain part near the town of Halych (2 km downstream) and the hilly-marshy part from the village of Kruzhyky (3 km downstream) at the transition from the mountainous to the plain part of the river. A structural and logical modeling scheme was developed, the main elements of which are: construction of DEM, determination of changes in the bedding surface, determination of water level rise for a certain time period. For the implementation of the modeling scheme for the flat part of the channel, topographic and special maps, remote sensing materials obtained from Landsat and Sentinel spacecraft were used, for the second hilly-marshy area - materials from UAVs, with the processing of all materials in ArcGIS using the HEC-RAS module. The analysis of the accuracy of determining the coordinates of the model points and testing the flooded area was carried out.