<p>The proposed work is aimed at studying the effect of porous structures of various shapes on the propagation of a dam break flows in a rectangular channel with a wet bottom. The study is based on a laboratory experiment involving the lifting of vertical gates and the formation of flood waves of a dam break. The vertical gate divides the rectangular installation into a tank and a downstream channel. The developed three-dimensional numerical model was tested by comparing with laboratory experiments and calculations by other authors. It has been found that the maximum reduction in the impact pressure value is achieved with the help of a triangular shaped obstacle, which reduces the potential of the earth dam break having porosity properties or even in the event of a dam collapse, then with the least damage. This form of the dam provides reliable protection against water flow, which can later be used to reduce the risk of serious damage to the earth dam break having porosity properties.</p>