The research involved a detailed analysis of transformations in water relations in the Wieczno Południowe (Wieczno South) lake drainage basin in central Poland, in the physical geographical region of the Chełmno Lakeland. Significant changes were identified in the water relations in the catchment, which were caused by a number of anthropogenic factors. The most significant factors include land development works, changes in land use (a decrease in wetland area in favour of arable land), and the extraction of water from Lake Wieczno South (for irrigation purposes) and the creation of a weir construction on its outflow. It has been shown that in recent years the drainage basin’s water resources have been affected by climate fluctuations manifested as an increase in sums of evaporation. As a result of the deterioration of water relations in the catchment, the hydrological type of some lakes (Płużnica, Wieczno North and Wieczno South) have changed, which unexpectedly resulted in an improvement of their water quality. Taking into account the forecasts for further climate change, this factor will probably have a decisive influence on the water relations of the studied area in the coming years.
This study presents the results of monthly examinations of the vertical distribution of water thermal structure (2008-2011) carried out over a four-year period in the deepest lakes located in the Kashubian and Brodnickie Lakelands and the Tuchola Forest1. Three lakes were selected for examination (Raduńskie Górne, Zbiczno and Ostrowite). Their maximum depths slightly exceed 40 m, and their surface areas range from 121 to 362.5 ha. The results of the measurements show that, despite only minor differences in depth, water temperature varied significantly between the studied lakes. These differences were mainly apparent in the extent of the epilimnion, water thermal stratification, and in the water temperature in the bottom-most layers in summer and winter. The diversity in thermal stratification of the lakes is mainly determined by their morphometric properties, their location above sea level, and the dynamic influences of winds.
The paper presents the changes that have occurred in the morphometry of Lakes Gopło and Ostrowskie, which are located
in central Poland. The analysis covered the period characterised by increased human interference into the water cycle, which has
been taking place continually since the mid-eighteenth century. On the basis of available cartographic materials (aerial photographs,
topographic maps, bathymetric charts of the lakes) and the authors’ own field measurements digital terrain models were developed
for the immediate environment of the surveyed lakes. These models, in turn, were used for measuring basic parameters characterising
the external dimensions of the lakes (surface area, length and maximum width, shoreline length) and their underwater relief (volume,
maximum and average depth). In addition, the selected indicators of the shape and form of the lake basins were determined. The results
showed a drastic reduction of water resources of the two lakes. The basin of Lake Gopło covers only the deepest parts of the former
reservoir, accounting for only 23.3% of the lake before 1772, and 32.5% of its former volume. In the case of Lake Ostrowskie the surface
area and volume decreased, respectively, by 23.5% (74.9 ha) and 21.3% (6 695 000 m3). Such large changes in surface area and volume of
both lakes have contributed to significant changes in other morphometric parameters and indicators. In particular, significant changes
were observed in relation to such morphometric characteristics as length and maximum width, as well as average and maximum depth.
The article discusses water level fluctuations in lakes and the associated changes in the lake surface and water resources in the years 1992-2011. On the basis of detailed field studies carried out in the hydrological year 2011, short-term and dynamic changes in the lakes’ hydrology were determined. Changes in hydrological lake types were evoked by unexpected hydro-meteorological situations, in particular high precipitation totals and sudden thaws in winter. The main symptom of the lake type change was the restoration, after nearly 10 years, of channels connecting the lakes. In addition, a strong interdependence was recorded in the difference between evaporation and precipitation, as well as the mean annual ranges of lake water levels in the years 1992-2010
The study focuses on short-term changes in surface water temperature in Polish lakes, and is based upon the experimental measurements of water temperature conducted every 60 minutes during the years 1971–2015. 19 lakes were selected on the grounds of their morphometric properties. The examinations were carried out in the system of expeditionary measurements (up to 8 days) and stationary measurements (over 2 months), and included temperature of surface water and its vertical distribution. The analysis of the results showed that temperature differences of water (daily amplitudes) were observed in both time and spatial distribution. The biggest differences in water temperature occurred during spring warming, and often reached 4–5°C, while rarely exceed 2°C in the remaining periods of the yearly cycle. The mean day value occurs twice; in the morning between 8:00 (7:00 GMT) and 11:00 (10:00 GMT), and in the evening at 20:00 (19:00 GMT) and 22:00 (21:00 GMT). Daily changes in the vertical distribution of water temperature are clearly visible down to the depth of 2.5–3.5 m, whereas are just perceptible to the depth of 5.5–7.0 m.
Aleksandra Lewandowska CDFMR and Adam Piasecki CDFMR
Effective water and sewage management is one of the most important enablers of sustainable urban development. In Poland, water and sewage management has been undergoing systematic transformation since the 1990s. This process intensified with Poland’s accession to the European Union in 2004. The aim of the work is to analyse and evaluate water and sewage management in cities in Poland in terms of sustainable development. This was made possible by selecting seven variables from which a summative index (SI) was calculated. The analysis revealed a number of positive changes that have occurred in this field. These were mainly: a decrease in water consumption in households and industry, and an increased share of wastewater treated biologically or using enhanced nutrient removal in total wastewater. An increase in SI was found in 98% of the researched cities. The largest improvement in water and sewage management took place in cities of populations below 100,000 and little industry, and in three large cities, namely Warsaw and Szczecin.
This paper presents an attempt to model water-level fluctuations in a lake based on artificial neural networks. The subject of research was the water level in Lake Drwęckie over the period 1980-2012. For modelling purposes, meteorological data from the weather station in Olsztyn were used. As a result of the research conducted, the model M_Meteo_Lag_3 was identified as the most accurate. This artificial neural network model has seven input neurons, four neurons in the hidden layer and one neuron in the output layer. As explanatory variables meteorological parameters (minimal, maximal and mean temperature, and humidity) and values of dependent variables from three earlier months were implemented. The paper claims that artificial neural networks performed well in terms of modelling the analysed phenomenon. In most cases (55%) the modelled value differed from the real value by an average of 7.25 cm. Only in two cases did a meaningful error occur, of 33 and 38 cm.
The aim of this paper was to present the possibility of integrating LIDAR data with bathymetric measurements in order to assess the changes in water resources and morphometric parameters. The area of study was Lake Kiedrowickie (Poland). A change in most of the morphometric parameters has been observed. Especially important was the drop in water resources which amounted to more than 30%. A significant decrease (13.4%) was also observed in case of the lake surface. In conclusion we state that the integration of valid bathymetric measurements with the LIDAR data gives the full capability to model the changes of lake morphometric parameters with unprecedented accuracy. A significant complementarity and synergy of applying both techniques has been stressed.
Katarzyna Peta, Karol Grochalski, Adam Piasecki and Jan Żurek
In the work, the most important factors which influence on the exploitative durability of heat exchangers are classified. Particular attention was paid to the compounds of sodium chloride used in the winter season for road maintenance. In order to determine their impact on automotive heat exchanger corrosion resistance, a test of heaters in a salt chamber which imitates the conditions of their work was realized. It also allows to verify the durability of these products. To evaluate the corrosion changes, observation with the use of light microscopy and scanning microscopy SEM were made supplemented with microanalysis of chemical composition by EDS spectroscopy method. Critical areas in the heat exchangers which are mostly exposed to damage including the formation of local corrosion pits were located and analyzed.
100CrMnSi6-4 bearing steel has been widely used for many applications, e.g. rolling bearings which work in difficult operating conditions. Therefore, this steel has to be characterized by special properties such as high wear resistance and high hardness. In this study laser-boriding was applied to improve these properties. Laser alloying was conducted as the two step process with two different types of alloying material: amorphous boron only and amorphous boron with addition of calcium fluoride CaF2. At first, the surface was coated with paste including alloying material. Second step of the process consisted in laser re-melting. The surface of sample, coated with the paste, was irradiated by the laser beam. In this study, TRUMPF TLF 2600 Turbo CO2 laser was used. The microstructure, microhardness and wear resistance of both laser-borided layer and laser-borided layer with the addition of calcium fluoride were investigated. The layer, alloyed with boron and CaF2, was characterized by higher wear resistance than the layer after laser boriding only.