Spectral analysis of water level fluctuations in Belarusian and Polish lakes

Abstract

Abstract. Data regarding 25 lakes (9 Belarusian and 16 Polish) provided the basis for spectral analysis of water level fluctuations. The obtained output data concerned a 55-year observation sequence covering the years 1956-2010. The selection of lakes was determined by two factors, i.e. data continuity and inconsiderable anthropogenic impact. The lakes were divided into three groups depending on the course of the water level spectrum. The first group included the highest number of lakes (14) which were distinguished by smooth curves with no significant peaks (e.g. Lake Wygonoszczańskie). The second group shows a four-year variability (e.g. Lake Łukomskie). The third group is distinguished by an even peak of three-year water fluctuation (e.g. Lake Łebsko). The location of the lakes categorised into those three groups suggests a certain regionalisation. The first group is represented by lakes of central and northern Belarus, and eastern Poland. The second group includes lakes of eastern Belarus, and the third group -lakes of central and northern Poland. This suggests that alongside local factors, the location of the distinguished groups of lakes may also be determined by regional factors. Presumably, continentalism of climate increasing in an eastwards direction is one of the key factors responsible for the detected regional diversity of lake water level fluctuations.

Spectral–time analysis of cycle fluctuations in lake water levels in Belarus and Poland

“…The typical representatives of the first group are STAN diagrams of lakes: Driviaty, Miastro and Lukomskoe. This statement overlaps with that referring to the groups of lakes separated earlier according to spectral analysis (Volchak et al 2017). The smallest area is covered by 3 enclaves comprising 4 lakes with 3 and 5-year cycles.…”

“…Nowadays, even if lakes with an unaffected hydrological regime can be selected, practically all basins are to a lower or higher degree subject to certain anthropogenic pressure. Therefore, the hydrological regime of the studied lakes is quasi-natural (Volchak et al 2017).…”

“…Characteristics of lakes and morphometric parameters of their basins and catchments determining water level fluctuations are presented in Tables 1 and 2 (Mironienko 1966;Choiński 2006;Volchak et al 2017). The maximum distance between the lakes from west to east amounts to 710 km -Lake Sławskie 16°01' E and Lake Senno 29°42' E, and from south to north to 360 km -Lake Sławskie 51°54' N and Lake Osveiskoe 56°01' N.…”

The effect of a water dam on Lake Powidzkie and its vicinity

“…Diagram of the effect of damming lakes on groundwaters in lake catchments: 1-groundwater table, 2-drilled water table of confined aquifer, 3-stabilised water table of confined aquifer, 4-direction of flow of groundwaters, 5-direction of infiltration, +Hincrease in the water level in the lake, +Q s -increase in statistical resources in the catchment, +Mf-increase in filtration to deeper aquifers, >q 1 -decrease in unitary groundwater inflow to the lake, -q 2 -reversal of the direction of groundwater flow in deeper aquifers (source: Nowak in press) water balance. Many factors can cause a decrease in the water level in lakes, as described in detail by numerous analyses (Ptak et al 2013;Bonacci et al 2015;Choiński et al 2016;Wrzesiński and Ptak 2016;Ptak et al 2017;Skowron and Jaworski 2017;Volchak et al 2017). In the context of the observed climate changes, activities aimed at water retention in the catchment will be of increasing importance.…”

Natural and anthropogenic conditions of water level fluctuations in lakes – Lake Powidzkie case study (Central-Western Poland)

“…Only after 2010 the process was temporarily inhibited as a result of both natural factors (high precipitation) and human activity (hydrotechnical infrastructure on the outflow from the lake) [NOWAK, PTAK 2018]. Studies concerning water level fluctuations in Polish lakes are difficult to refer to such a situation [KOWALIK et al 2008;PTAK et al 2017;VOLCHAK et al 2017;WRZESIŃSKI et al 2018], because in the case of the analysed lake anthropogenic activities were of key importance [NOWAK 2018;NOWAK, PTAK 2018], and such measures were not implemented in other cases. The course of water level fluctuations in Lake Powidzkie confirms the statement on the complexity of the process in reference to the water level dynamics.…”