Lietuvos ežerų vidutinio vandens lygio vertinimo galimybės. (Lithuanian)

The article discusses the peculiarities of methodology for calculating the mean water level in Lithuanian lakes. It analyzes the mean level value differences received when calculating different length data sequences and data suitability of various seasons. The data about the three gauge stations of the longest operation (Totoriškės Lake in Trakai, Tauragnas Lake in Tauragnai and Žeimenys in Kaltanėnai) that characterize the natural lake level regime are examined. The results show that the recent method of calculation of the mean level (when using all data of measurements or focusing on the summer season level) is basically correct but uncertain and not sufficiently accurate. In order to simplify and qualify this methodology we need to have much more information about the hydrological regime of the lakes in Lithuania. For the calculating of the annual mean level based on measurement results, as long as possible period of time should be used. The analysis showed that the thirty-year period was too short for calculation of the mean level values (values differences in various time periods up to 10 cm). [ABSTRACT FROM AUTHOR]

Straipsnyje aptariami vidutinio ežero vandens lygio nustatymo metodikos ypatumai. Analizuojami vidutinio lygio reikšmių skirtumai, gauti apibendrinant skirtingos trukmės duomenų sekas bei geriausiai vidutinį lygį reprezentuojančio sezono parinkimo aspektai. Nagrinėti trijų ilgiausiai veikusių VMS (Totoriškių ež. ties Trakais, Tauragno ties Tauragnais ir Žeimenio ties Kaltanėnais), apibūdinančių natūralų ežerų lygio režimą, duomenys. Rezultatai rodo, kad dabartinė vidutinio lygio skaičiavimo metodika (naudojant visus matavimų duomenis arba orien- tuojantis į vasaros sezono vidutinį lygį) iš esmės teisinga, bet nekonkreti ir nepa- kankamai tiksli. Norint ją supaprastinti ir patikslinti reikia turėti žymiai daugiau informacijos apie ežerų hidrologinį režimą. [ABSTRACT FROM AUTHOR]

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