In this article, attention focused on the analysis of climatic factors of river flow formation and their changes. In the coming years, it planned to build cascades of hydroelectric power plants on the Chatkal River, in connection with the study of the Chatkal River regime, it becomes especially relevant. Long-term fluctuations in runoff determined by precipitation during the cold period in the catchments and the temperature regime of the summer months. From 1933 to 2022, the average annual air temperature in the Chatkal River basin increased by 2.2 0C. Therefore, in general, from 1926 to 1995. The average annual consumption increased on the Chatkal River by 16.4%, on the Ters River by 1.56%. In the cold season, the lower average monthly water consumption of the Chatkal River is 15.5 m3/s, which is 21 times less than the large water consumption in June with an average annual consumption of 64.3 m3/s. The maximum water consumption is 450.0 m3/sec, the average maximum water consumption is 326.0 m3/sec. The average slope of the river i = 13.0%, the weighted average i = 8.3%. The average height of the catchment area is 2720.0 m. Using the method of hydrological analogy, according to the well-known average annual flow modulus in the catchment area of the Chatkal River, was calculated the average flow of more than 10 tributaries. According to the results of calculations, for the opening of the Chatkal hydroelectric dam, the average flow rate of the Chatkal River at the mouth of the Ters River at 25% water content should be assumed to be 75.6 m3/s.