Method of Assessing Complex-Formed Elements of Water Balance (Total Evaporation and Moisture Reserves) of the River Basin

Abstract

There is considered the determination of total evaporation and the change in basin moisture reserves at given annual and seasonal values of precipitation and river runoff over a long-term period of hydro meteorological observations. In the engineering hydrology practice,the most common approach to determining total evaporation using only data on runoff and precipitation is to estimate it by the difference in total precipitation and river runoff. Moreover, the assumption is made that the change in basin moisture reserves for medium and large river basins over a sufficiently long period of time is close to zero. Based on this, in this work, we developed a technique that allows, when determining the total annual and seasonal evaporation from the land surface and reservoirs, to take into account the change in basin moisture reserves, since under real conditions the formed basin moisture reserves of the previous period are involved in the formation of both river runoff and total evaporation of next period. As the main mathematical tool, the work uses the correlation equation interlinking the considered elements of the water balance. Equations are obtained that determine the share of moisture reserves involved in the formation of river flow and total evaporation. Equations have been obtained that determine the proportion of basin moisture reserves involved in the formation of river runoff and total evaporation. Equations are proposed of the connection between runoff and precipitation and changes in annual moisture reserves with the share of moisture reserves involved in the formation of river runoff. The equations allowed estimating the values of total evaporation and moisture reserves in the basin in relation to the Don basin. Equations of the river runoff dependence on total precipitation of the Don basin have been obtained. As the initial hydro meteorological material there were used the data of the State Water Registry, surface water resources and hydrological yearbooks, as well as observational data from information and reference systems, such as the website of the All-Union Research Institute of Hydro meteorological Information – World Data Center – www. meteo.ru. As a result of the conjugated timing analysis of the elements of the water balance of the Don River basin, it has been established that in the basin the influence of natural factors is dominated.

Investigation of the long-term variability of the elements of the water balance of the river basin in the modern climate

“…Возникает необходимость оценки степени изменчивости элементов водного баланса (ЭВБ) речного бассейна за длительный период в современном климате и климате будущего. В работах [4][5][6] обнаружена недостаточность подхода к установлению стационарности формирования речного стока в течение длительного периода. В целях решения проблемы управления водными ресурсами необходимо подвергнуть сомнению представления, которые касаются стационарности режима вод речных бассейнов.…”