IWRA Proceedings

Abstracttopic: Regional sector ON THE NECESSITY OF RECONSIDERATION OF THE WATER BALANCE EQUATION COMPONENTS. IOFFIN Z.K. Vologda State Technical University, Vologda, Russia The structure of the water balance equation that is used for a long time in which precipitation is spent on evaporation, runoff and closure error is, in our opinion, imperfect. Such a kind of the equation doesn't give even an opportunity to determine the infiltration precipitation losses, not to mention such water balance elements as absorption, runoff and precipitation at different stages of water formation and runoff. That supposes essential errors at determining of any of the equation components. It is quite clear that the already traditional infiltration value determination on the basis of the long-term observations over the underground waters level, is used only at the experimental river basins. The mass usage of the traditional infiltration determination method is quite ineffective and labor-consuming. In the year 1974 in the framework of the International hydrological decade State Hydrology Institute (St. Petersburg) published the monograph "Global Water Balance and Water Resources of the Earth". Unfortunately, the water balance equation used in this monograph, also consisted of the same components, that is, precipitation, runoff and evaporation. Since there are underground water reservoirs and their infiltration supply, the infiltration as a component of the water balance equation was used in this monograph indirectly in calculations of evaporation or runoff. It depended on the hydrological study of the region and availability of the survey data. In case there were data on precipitations and evaporation and absence of the runoff survey, then the water balance infiltration equation was indirectly included into the runoff, accordingly increasing it. This means that the water resources calculations were made with a certain error. If on the contrary the investigators had survey data on the runoff and precipitations, then the evaporation was increased by the infiltration value. In any case the water balance is distorted and this means that the mentioned monograph content requires certain corrections. We suggest a new linear and correlative model of the water balance equation that could serve the base for reconsideration of the water balance components equation introduced in the earlier mentioned monograph. Our model lets us on the basis of the survey data on precipitations and river runoff define analytically not only the infiltration value but that of the evapotranspiration and evaporation from the water surface, absorption, runoff losses at the drop of each flood, precipitations losses at the surface slowing up at the water basin. The Linear and correlative equation model is checked on materials of the survey data of the rivers of Cuba and Russia and shows a good correlation of the calculated and real water balance equation components.