WE have developed and tested a practical tool for determining, calculating and identifying flooded lands on the examples of flooded areas of the Irpin River Valley. Satellite images were used to determine the flooding zone. GIS analysis was carried out using the ArcGIS Pro program, which made it possible to automatically calculate the area of flooded lands using a range of indices. Using open data from the state land cadastre, we can determine the list of Territorial Communities that were affected by the war and flooding of land plots as a result of the dam being blown up and the filling of the Irpin River Valley with water from the Kyiv Reservoir. Using open data from the state land cadastre, it is possible to determine the list of land plots whose owners cannot use the land plots. This information is needed to make management decisions regarding land protection measures and to determine the circle of landowners and the legal consequences and actions of state authorities and local governments.