The Water Balance of Lithuanian Closed Glacial Lakes
- Bibliographic Description: Gintaras Valiuškevičius, „Nenuotakių ledyninės kilmės Lietuvos ežerų vandens balansas“, @eitis (lt), 2018, t. 1 104, ISSN 2424-421X.
- Previous Edition: Gintaras Valiuškevičius, „Nenuotakių ledyninės kilmės Lietuvos ežerų vandens balansas“, Geografijos metraštis, t. 32, 1999, p. 65–74, ISSN 0132-3156.
- Institutional Affiliation: Vilniaus universiteto Gamtos mokslų fakultetas.
A dense network of meteorological observations in Lithuania would prevent from missing distinct azonal anomalies of precipitation. Anomalies of evaporation have neither been recorded in any water balance station operating under natural conditions similar to those in Lithuania. Thus, a climatically predetermined closed character of lakes (I > P) in a long-term period is impossible in Lithuania. We may assume that the ratio between P and E in humid zones determines the change of lake parameters over time, whereas the ratio between I and O – the spatial distribution of lakes. The research which is presented in this paper is based on the short-term water balance investigations. These investigation were fulfilled in the closed lakes in various hydrological region of Lithuania from 1976 to 1996.
Short-term water balance investigations in concrete closed lakes revealed that the ratio between the water balance elements in them may vary considerably. Probably to the highest extent it depends on the genesis of lake depressions. As for instance, the water balance of closed and periodically drained glacial lakes is determined by: 1) soils of the basin and depression, which define the ratio between the ground water input and output, 2) lake depth (deeper lakes are more abundantly supplied with the ground water), 3) situation of lakes with regard to morainic chains and channel lake valleys (the lakes situated in the central parts of morainic tracts are weakly supplied with the ground water, whereas lakes occupying fragments of channel lake valleys are hydraulically linked), 4) water exchange between ground horizons cut across by depressions. The ratio between ground and surface water input and a ground water output depends on the humidity of periods. A humidity of periods changes depending on the season and long-term climatic cycles. Therefore it is necessary to repeat the short-term water balance researches in the periods with different humidity.
Keywords: closed lake, water balance, endorheic basin, Lithuanian lakes.