FIELD: construction.SUBSTANCE: invention relates to flood prevention techniques. Quick-erect shield for the coastal dam to use in case of a flood contains a coastal dam with the possibility of blocking the main river bed. Coastal dam consists of three parts: two identical parts are located along the banks of the river, along its main channel, and the third part, the main part, rigidly connects these two parts perpendicular to the main river bed. Main part of the coastal dam consists of two oppositely located permanent shields, made in a rectangular shape and rigidly connected to the parts of the dam located along the banks of the river, and in the opening formed by permanent shields, there is a central rectangular prefabricated shield, movably connected by means of, for example of the "groove-spike" type, with permanent shields and to be fixed to them by means of a locking mechanism made, for example, in the form of spring-loaded movable pins, whose housing is fixed to the permanent shields. There are holes f
