AbstractWater-balance forecasts must be based on expected long-term changes in water utilization and the use of the differentiated water-balance equation. Through use of this equation the water balance of the USSR can be broken down by major economic regions. Future transformations of the water balance should be designed to increase the infiltrating capacity of the soil to reduce surface runoff and increase the amount of water that can be used for the production of plant matter (crops). The relationship between increases in crop yields and reduction of surface runoff is illustrated by the Don River.