<p>To assess changes in the volume of water in reservoirs, it is necessary to determine the dependence of the values of the volume of water discharged from the reservoir on changes in the water level. The study is devoted to the development of a method for calculating the discharge capacity of the wateroutlet on the example of the Talimardjan reservoir. When determining the fl ow discharge of water from reservoirs, the magnitude of the opening and closing of the outlet gates is of great practical important. The article analyzes the relationship between the opening height of the gate and the water discharge. To determine the coefficientof water discharge at the outlet, the ratio of different water levels and the opening height of the gate were analyzed. The results obtained were processed using mathematical statistics methods. As a result of these studies, a new dependence for the fl ow coefficient is obtained. The proposed calculation method makes it possible to quickly determine the amount of water discharged from the reservoir.</p>