Volumen 20 (2020): Edición 2 (June 2020)

The paper presents the applicability of LiDAR data in limnological research with respect to the identification of the shoreline of lakes, and consequently the scale of overgrowing of lakes. Data obtained from the Head Office of Geodesy and Cartography from the period 2011 2016 provided the basis for the identification of shorelines for 14 lakes of the Pomeranian Lakeland. The paper employs the orthophotomap for the determination of the range of lake vegetation. Using the line determined based on the orthophotomap and that determined based on LiDAR points, the zone of overgrowing of the analysed lakes was delineated. In all the analysed cases combined, the water surface area was found to be reduced in comparison to the shoreline identified through LiDAR scanning by 161.5 ha, suggesting a 21.2% share of vegetation in the surface area of lakes.

In the belt of the Polish Uplands, including the Holy Cross Region, lakes occur sporadically. In some places, however, they are somewhat more abundant. They are usually objects with a small surface area. The majority of them have not been subject to thorough investigation. Therefore, the objective of the paper is the expansion of knowledge regarding these lakes. The paper among others presents the characteristics of several lakes with aeolian genesis located on the Przedbórz Upland in the catchment area of the Wierna River and in the Nida Basin near the towns of Busko-Zdrój and Pińczów. The study results determine the morphometric parameters of the lakes, also pointing to an exceptionally high variability of physical and chemical water properties, as well as the possibility of periodical disappearance of the lakes. Moreover, the study results provide a necessary and solid basis for further investigation of the lakes, which in the context of the observed increasingly serious water deficit and decrease in the level of surface waters and groundwaters is undoubtedly of high importance.

The creation of digital bathymetric models (DBM) of lakes allows not only for storage of the data on depths and shorelines in a standard format, but also for the estimation of the major morphometric characteristics of the reservoirs. To calculate the water, thermal, and chemical budgets of large lakes, it is important to know their hypsometry. We developed a new digital model of Lake Ladoga, the largest European lake, which was done to identify and correct topographic data errors, as well as to identify more depth points. The produced bathymetric model of the lake allowed for the updating of morphometric characteristics. The lake-bottom grid of 0.5×0.5 km with 70190 depth points of interest was produced using the kriging procedure with the mean error ME = 0.05 m and root mean square error RMSE = 5.6 m. The statistical characteristics of the lake depth and slope are determined on the basis of the advanced digital model of the lakebed relief. The form of the lake depression corresponds to the convex type (microtype) and bears some similarity to lakes Erie, Huron, Vanern, and Malaren. We describe how the bathymetric model has been developed and the morphometric characteristics of the lake have been corrected. We also discuss the results of its application in limnological investigations. A relationship has been established between surface water temperature, transparency and the bottom depths for the various seasons of Lake Ladoga.

The aim of this study was to reveal the chemical composition of bottom sediments in karst lakes located in the northern part of Połaniec Basin (eastern part of the Nida Basin, vicinity of Staszów municipality). A field investigation was carried out in 2010 on four lakes: Duży Staw, Donica, Dziki Staw and Łajba. The contents of a very wide range of chemical elements were determined, which is a rarity. On the basis of our research, it was found that the analysed lakes differed considerably between each other in spite of their close location. In general, sediments contained fair amounts of organic substances as well as Fe, Al, Ca and Mg due to the type of source rock and soligenic lake water supply. Increased concentrations of V, Cr and Ni might be explained by the weathering of rock material. In turn, higher contents of Zn, Pb, Cu and Co in the bottom sediments from Duży Staw indicated anthropopression. The measurement results obtained in this study will allow a future comparative analysis with bottom sediments from other lakes.

The paper discusses the impact of lake morphometric parameters on the thermal structure of water during the period of summer stagnation. The summer period in the lakes is characterized by clearly expressed properties of the thermal structure of water, differentiating lakes from one another. The study was carried out on 141 lakes in northern Poland, for which at least 3 vertical water temperature measurements were taken in different years. They showed a significant influence of lake basin morphometry upon the thermal structure of water in lakes. In general, measurements of the vertical distribution of water temperature showed clear diversity, and depending on the depth also thermal layers (epi-, meta- and hypolimnion). The results of the analysis of 8 lake morphometric parameters and 10 thermal stratification parameters revealed the existence of significant dependencies between them. The best-preserved relations (statistically significant) occurred between the parameters characterizing the lake depth and meta- and hypolimnion properties, as well as the thermal stratification factor and heat content in a unit of volume.

The article presents the results of observations and research on the dynamics of exogenous erosion processes on the shores of lowland reservoirs in Belarus. Features and regularities of the dynamics of development of exogenous shores subject to abrasion-processing and an assessment of planned and profile stability of coastal slopes on the basis of proposed criteria are presented. The relationship between exogenous processes and accumulation processes was determined, the approaches and criteria for determining the stability of reservoir shores based on the hydrological regime of reservoirs and ground conditions were developed.