The Lower Vistula and Its Ice Problems

In many countries of the northern hemisphere during winter period ice forms appear on various water bodies, which results in significant changes of physical, chemical and ecological conditions. These changes are different in rivers, channels, lakes or once-through reservoirs. On the terrain of Poland ice always caused considerable problems affecting intensive inland navigation and other river use. These problems appeared especially on the Vistula River, which in 17th and 18th century was one of the most navigable rivers in Europe. The Vistula is the largest Polish river, which flows from the south in the Carpathian Mountains to the Baltic Sea in the north. It is the second largest river, after Neva, of the Baltic Sea catchment. The length of the Vistula is 1047 km and its catchment amounts to 194 thousand km2. The predominant part of the Vistula river basin (87%) is now on Polish territory and the remaining (13%) catchment is in Belarus, Ukraine and Slovakia. The course of the Vistula can be divided into three distinctly different sections: upper, middle and lower. These river sections have appropriate catchments with their tributaries. There are hydraulic structures on the main river course and on its tributaries which serve navigation, hydroenergy, flood protection, water supply and recreation. All over the Vistula catchment there are frequent floods during spring and summer time resulting from excessive precipitation but in winter caused by ice phenomena. Numerous flow problems appear especially along the lower Vistula course because of ice phenomena and they result very often in severe flood problems. The Vistula has a very variable time and spatial discharge, because of existing climate conditions over its catchment. The aim of the paper is to present hydraulic and hydrologic characteristics of the Lower Vistula river with special emphasis on the management of this river section for navigation, hydroenergy, flood protection and water supply in view of ice phenomena appearing there. Information concerning changes of water characteristics due to various water temperatures are presented as well as on the formation of various forms of ice in flowing water. Numerous ice studies were carried out in Poland and especially on the Lower Vistula section as it was very ice prone and where many ice jams and ice-jam floods occurred. A special hydraulic situation existed at the mouth of the Vistula, which caused important floods in the 18th century and resulted in the construction of a special direct channel to the sea (Przekop Wisły) solving flood problems in this area. Information is presented on changes in open channel flow due to the appearance of ice cover and other ice forms. The paper includes ample information on the run, consequences and studies connected with a very important ice-jam-flood on the upper part of Włocławek reservoir in 1982.

The influence of treated wastewater from the Lodz city agglomeration on the ice regime and water temperature of the Ner river

The study attempts to answer the following question: Does human impact contribute to changes recorded in the Ner river ice regime? In replying to this question, data on water consumption in Lodz (Łódź) (a city in central Poland) in 1951–2017 were used, as well as observations of ice cover and all ice phenomena for the same period. The ice regime and water temperature of the river have changed over the past 70 years. The changes result not only from changes caused by global warming but also from additional fluctuations in this temperature as determined by changes in the quantity and quality of wastewater discharged into the river from the Lodz city agglomeration. The frequency of ice phenomena in the river decreased, and their duration dropped by almost half. This tendency was compounded by a decrease in number of days with ice phenomena, which in turn was caused by a rapid increase in the amount of waste and thermally polluted waters supplied from Lodz. The river water temperature has now stopped increasing. The course of the river ice regime now resembles that of a natural watercourse again.

Ice phenomena in investigations of Polish lakes

The paper presents nearly 150 years of history of ice research conducted on Polish lakes. In the first stage, these were observations and expedition studies that had an exploratory purpose. It was not until the 1920s that stationary measurements on several lakes were introduced. Unfortunately, the outbreak of World War II interrupted these observations. After the war, they were resumed in 1946, but the real beginning of investigations of ice phenomena on lakes is taken to be 1960. At present, stationary measurements of ice phenomena are conducted on about 70 lakes located mainly in northern Poland. Besides the purely explorative purpose, experimental research on ice phenomena on lakes has also contributed to the development of a measurement methodology. The author of this paper took part in numerous experimental studies conducted on over 30 lakes for which the ice results are partially presented below.

To issue of gorges and ice jams in the Kuban river basin

Purpose: analysis of quantitative indicators of actual сongestion and ice jams in the Kuban river basin with subsequent intra-basin zoning of the parameters studied. Materials and Methods: data from hydrometeorological observations of ice phenomena were used. The summary calculation of the quantitative indicators of gorges and ice jams along the river Kuban, as well as for each basin of tributaries of the first order was carried out. Results: as a result of the analysis, it was found that the cases of maximum ice jams above the “0” graph in the river Kuban basin were observed more often than the maximum gorge rises. On the river Kuban the number of jams was 90, gorges – 64; in the river Belaya basin number of jamming phenomena was 96, gorges – 9; in the river Laba basin – 43 ice jams and 18 gorges; on the river Pshish the number of jams – 31, gorges – 6; in the river basin Urup the number of jams is 10, and the number of gorges is 20; the river Bolshoi Zelenchuk basin has 25 jams, and 5 gorges. The maximum rise in the water level during jams was 248 cm on the river Pshish at the Bzhedukhovskaya gauging station. The highest water level during gorge events was also recorded on the river Pshish in the aul Teuchezhkhabl and amounted to 386 cm. Most of the recorded cases of water level rise in the presence of gorge phenomena occur at the end of December and the second decade of February. There are no observational series of gorge events at most gauging stations, but, according to available data, most gorge events occur at the end of January and the second decade of February. Conclusions: gorges and ice jams are very dangerous natural phenomena and therefore require promptness and accuracy of forecasting. The solution of such problems is impossible without a network of hydrological posts and observation points, which is currently underdeveloped. Therefore, thickening and improving the existing observational network is one of the main solutions to this issue.

CHARACTERISTIC FEATURES OF THE AUTUMN ICE REGIME OF R. ZHAYIK (URAL)

This study considers the change in the timing of the appearance of autumn ice events on the river. Zhayik (Ural) related to anthropogenic activities and climate change. Autumn ice phenomena include floating ice (lard, shuga, snowflake) and the establishment of ice composition. As studies have shown, there is a tendency of later appearance of autumn ice phenomena (by 6...9 days) and the establishment of ice formation on the river (by 9...11 days), as well as a slight increase in the duration of the ice formation period (by 2...3 days).

The Influence of Shadow Effects on the Spectral Characteristics of Glacial Meltwater

The phenomenon of shadows due to glaciers is investigated in Antarctica. The observed shadow effect disrupts analyses conducted by remote sensing and is a challenge in the assessment of sediment meltwater plumes in polar marine environments. A DJI Inspire 2 drone equipped with a Zenmuse x5s camera was used to generate a digital surface model (DSM) of 6 King George Island glaciers: Ecology, Dera, Zalewski, Ladies, Krak, and Vieville. On this basis, shaded areas of coves near glaciers were traced. For the first time, spectral characteristics of shaded meltwater were observed with the simultaneous use of a Sequoia+ spectral camera mounted on a Parrot Bluegrass drone and in Landsat 8 satellite images. In total, 44 drone flights were made, and 399 satellite images were analyzed. Among them, four drone spectral images and four satellite images were selected, meeting the condition of a visible shadow. For homogeneous waters (deep, low turbidity, without ice phenomena), the spectral properties tend to change during the approach to an obstacle casting a shadow especially during low shortwave downward radiation. In this case, in the shade, the amount of radiation reflected in the green spectral band decreases by 50% far from the obstacle and by 43% near the obstacle, while in near infrared (NIR), it decreases by 42% and 21%, respectively. With highly turbid, shallow water and ice phenomena, this tendency does not occur. It was found that the green spectral band had the highest contrast in the amount of reflected radiation between nonshaded and shaded areas, but due to its high sensitivity, the analysis could have been overestimated. The spectral properties of shaded meltwater differ depending on the distance from the glacier front, which is related to the saturation of the water with sediment particles. We discovered that the pixel aggregation of uniform areas caused the loss of detailed information, while pixel aggregation of nonuniform, shallow areas with ice phenomena caused changes and the loss of original information. During the aggregation of the original pixel resolution (15 cm) up to 30 m, the smallest error occurred in the area with a homogeneous water surface, while the greatest error (over 100%) was identified in the places where the water was strongly cloudy or there were ice phenomena.

Estimation of the Dependence of Ice Phenomena Trends on Air and Water Temperature in River

The identification of changes in the ice phenomena (IP) in rivers is a significant element of analyses of hydrological regime features, of the risk of occurrence of ice jam floods, and of the ecological effects of river icing (RI). The research here conducted aimed to estimate the temporal and spatial changes in the IP in a lowland river in the temperate climate (the Noteć River, Poland, Central Europe), depending on air temperature (TA) and water temperature (TW) during the multi-annual period of 1987–2013. Analyses were performed of IP change trends in three RI phases: freezing, when there appears stranded ice (SI), frazil ice (FI), or stranded ice with frazil ice (SI–FI); the phase of stable ice cover (IC) and floating ice (FoI); and the phase of stranded ice with floating ice (SI–FoI), frazil ice with floating ice (FI–FoI), and ice jams (IJs). Estimation of changes in IP in connection with TA and TW made use of the regression model for count data with a negative binomial distribution and of the zero-inflated negative binomial model. The analysis of the multi-annual change tendency of TA and TW utilized a non-parametric Mann–Kendall test for detecting monotonic trends with Yue–Pilon correction (MK–YP). Between two and seven types of IP were registered at individual water gauges, while differences were simultaneously demonstrated in their change trends over the researched period. The use of the Vuong test confirmed the greater effectiveness of estimates for the zero-inflated model than for the temporal trend model, thanks to which an increase in the probability of occurrence of the SI phenomenon in the immediate future was determined; this, together with FI, was found to be the most frequently occurring IP in rivers in the temperate climate. The models confirmed that TA is the best estimator for the evaluation of trends of the occurrence of IC. It was shown that the predictive strength of models increases when thermal conditions are taken into consideration, but it is not always statistically significant. In all probability, this points to the impact of local factors (changes in bed and valley morphology and anthropogenic pressure) that are active regardless of thermal conditions and modify the features of the thermal-ice regime of rivers at specific spatial locations. The results of research confirm the effectiveness of compilating a few models for the estimation of the dependence of IP trends on air and water temperature in a river.

Ice Regime of the Kozłowa Góra Reservoir (Southern Poland) as an Indicator of Changes of the Thermal Conditions of Ambient Air

Ice phenomena are construed as the occurrence of ice in water irrespective of its structure, form, and duration. One of the most frequently discussed research problems is the possibility of using long-term ice phenology as an indicator of changes of the thermal conditions of ambient air. The study used correlation analysis and regression models in order to determine changes in the parameters studied over time. In order to compare the ice regime of the study reservoir and other lakes in the region, discriminant function analysis, principal components analysis (PCA), and canonical redundancy analysis (RDA) were applied. During the 52 winter seasons studied (1964–2015), there were weak but still statistically significant trends concerning the increase in air temperature in the region (by 0.3 °C per decade), the reduction in the number of days with ice cover (by 8.6 days per decade) and the decline in the maximum and average thicknesses of lake ice (by 2.0 cm and 1.2 cm per decade). The low average depth and volume capacity are reflected in the rapid freezing rate of the reservoir, and its location results in a longer duration of ice cover, greater ice thickness, and later dates of its melting.

ICE CONDITIONS IN THE SOUTHEASTERN BALTIC SEA FROM SATELLITE DATA (2004–2019)

The Russian part of the Southeastern Baltic Sea has a specific ice regime, which is determined by geographical location and climate conditions. Satellite data are widely used to study the propagation of sea ice. The advantages of radar images (RLI) from satellites equipped with synthetic aperture radar (SAR) are a large area coverage and independence from daylight and cloud-cover conditions. There were 840 SAR images of the Southeastern Baltic Sea analyzed for the period from December 1 to March 31, 2004–2019. It is shown that in modern conditions ice phenomena in the southeast Baltic do not occur every year. It is shown that in recent conditions ice phenomena do not occur every year in the Southeastern Baltic Sea. The revealed spatial and temporal variations in the ice regime are determined by the consequences of climate changes in the Southeastern part of the Baltic Sea. The intensity of ice formation depend on temperature conditions. Ice formation begins mainly in the second half of January-early February. The average duration of sea ice period is 22 days per season. The probability of observing sea ice from a satellite is maximum in February. Stable ice fields occur when the daily average air temperatures drop below –5 °C during 5 or more days. The maximum duration of ice period and maximum ice extent are observed in February.