DETERMINATION OF UNDERGROUND CONSTITUENT OF RIVER RUNOFF
ACCORDING TO HYDROCHEMICAL DATA BY THE EXAMPLE OF UPPER VOLGA RIVER
IN THE ZONE FROM THE SOURCE TO STARITSY TOWN

Yakovlev Peter Ivanovich, Hidrologist of first category, Research center «Geoecology» (63 15 let Oktyabrya street, Tver, Russia), akva-petr.1947@mail.ru

556.3+556.5

Background. The article considers a problem of accuracy of calculating underground inflow into rivers according to hydrological data. Low-water hydrological survey allows to determine accretion of underground runoff with different absolute error, depending on the volume of the measured minimal runoff and on the variation of underflow. Therewith, the relative standard water discharge measurement error is – ±3,5 %; in the measured part of the river – ±7 %. Change of parameters of the underflow is associated with the differences in lithology of soils, composing the riverbed, i.e. with soil type and thickness, occurrence conditions.
Materials and methods. To increase the accuracy of calculation of underground inflow into rivers the author suggests to use an equation of riverbed ionic (saline) balance with minimal low water flow not more than 30–40 м³/с. An important result of hydrochemical calculations is determination of ionic flow that allows to calculate the parameters of underground inflow in a part of a river, stipulated given chemical characteristics of underground waters.
Results. As is known, in Upper Volga river in the period of low flow the concentration of certain ions and general mineralization in underground waters is 2–3 times lower then in river water. Measurement of electroconductivity of natural waters prove such conclusion. The above mentioned ionometric correlation in river and underground waters allows to determine underground inflow according to hydrochemical data with lower error compared to the traditional hydrometric method.
Conclusions. Previously, the Belorussian researcher V. V. Drozd determined an underground constituent of river runoff by the hydrochemical approach in the period spring high water in small rivers of his home region. In this case the hydrochemical method is used to increase accuracy of calculating underground inflow into rivers according to hydrological and ionometric data. In conditions of great differences in mineralization of river and underground waters the error of determination thereof may be decreased two and more times.

underground waters, river waters, surface waters, source area, discharge area, geological and structural analysis, hydrochemical testing, thermometric, hydrometric survey, ion flow, complex method.

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