Our paper deals with the solution of ecological flood-type accidents and the mitigation of their impacts during their occurrence. The main task is to defeat an accident on a watercourse as soon as possible, efficiently and economically, by arranging a floating boom. Closer specifications of the paper involve the technical use of floating booms and the calculation of the resistance force, which influences the application of a floating boom at a given current velocity. The calculations show that flow and size of a river flow has a direct effect on the size of the force that impinges on a barrage. The maximum river flows are in the time of January and February. The smallest river has flow of about 2.346 m³s^-1 in this time, and the biggest river has a flow of 28.88 m³s^-1 in defined time.