In the summer of 2022, an environmental disaster unfolded on the Oder River. Though the disaster was caused by humans, it was the river’s natural ecosystem that paid the heaviest price.

One more time we would like to pay attention of especially of the hydraulic engineer audience to bankfull stage and discharge. Along the paper we show commonly accepted definitions of it and ways of calculations. It is difficult to determine the size of the bankfull flow level, that is why the authors are presenting many selected methods. Some of the methods allow the determination of biotic bankfull flow through the occurrence of zones of vegetation characteristic and based on the observation of the occurrence of ground beetles (e.g. the Woodyer and the Radecki-Pawlik and Skalski methods). Some of the methods – most popular- are using morphometric parameters (e.g. the Williams, the Hey and Thorne, the Gauckler-Manning and finally the Lambor methods).

We believe that the value of bankfull discharge would be accepted as a supporting tool for designers, hydraulics engineers and managers, especially those who care about river channel environment and cooperate with fluvial geomorphologists- and biologists as well as environmental agencies.

On the Polish-Czech Odra river section between Chalupki (Poland) and the Olza river mouth there are unique in European scale meanders (km 21.3 - 26.8). In the 20th century the break-up of two meanders caused by floods in 1967 and 1997 occurred. The total length ofmeandering section has become shorter and the hydraulic gradient increased. The sediments eroded and transported by the stream have settled in different zones of the meandering section. In 1997 the inlet to the meander I was blocked by settled sediments causing the break-up of this meander. The paper presents the preliminary estimation ofmorphological changes of the river bed and the physical and rheological characteristics for settled sediments.

Water reaches a river in the form of surface runoff (precipitation that has not seeped into the ground) or underground outflow (groundwater). Both of these factors affect the erosion and river deposition processes that shape the river valley. Understanding them is crucial for effective river management.

The purpose of the research is to establish the total number of ponds in Ukraine and to analyse the territorial distribu-tion in the administrative areas, as well as in the river basin districts, as the main hydrographic units of water management. Cadastral data of the State Agency of Water Resources of Ukraine regional offices as of 2019 was used in the research (as to Crimea, Donetsk and Luhansk regions we applied the data as of 2014). According the researches there are 50,793 ponds in Ukraine with a total water table area of 2,92899 ha and the volume of 3,969.4 mln m3 of water in 2019. The quantitative distribution of ponds across Ukraine is unequal. Most of them are concentrated in the central part of the country (10.5% of the total number of ponds in the country are in Vinnytsia region). Least of them are in Luhansk region (0.7%). Almost half of the ponds are located in the Dnieper River Basin (48.5%). The lowest quantity of ponds is in the Black Sea Basin (1.2%). The regulation of river basins districts (the rivers of the Sea of Azov, Crimea and Black Sea Basins) reaches 0.71–0.77. As of 2019, 28% of the ponds are rented out. In order to identify the real status of the ponds (both quantitative and qualitative), their recreational role, the environmental impact and the regulation of the hydrographic network in Ukraine, it is necessary to increase the attention to ponds monitoring.

The upper section of the Bystrzyca River has a character of trout and grayling zone of river. The aim of the study was to determine the species composition of fish in the upper section of the Bystrzyca River and attempt to evaluate angling pressure on fish in this section of river based on analysis of records of amateur fishing. To determine the fish composition the control fishing was conducted using electric fishing gear. The assessment of angling pressure was based on the analysis of 2135 records of fishing in the mountain type rivers in 2012 year, obtained from PAA Lublin. The brown trout and grayling were a dominant fish species in the upper section of the Bystrzyca River, and the first of them was present on the whole length of the river and had the highest average density. The changes of fish community along the river course from Salmonids lead to an increase of the share of Cyprinids fish has been observed. Analysis of records of ama-teur fish catch revealed that the upper section of the Bystrzyca River is under considerable of angling pressure and the most commonly fished species was brown trout. However, the properly carried fishery management on this section of river and the establishment of „no kill” zone allows for proper maintenance of the populations of fish species valuable for anglers.

The paper aims to present directions of transformation of riverside areas in Wrocław implemented in 2012-2018 as well as planned investments within Przedmieście Oławskie revitalization program. Przedmieście Oławskie, a quarter housing estate from the turn of the 19th and 20th centuries is another area being regenerated in Wrocław after Nadodrze. The article outlines projects defined in the Local Revitalization Program for the years 2016-2018, responding to the identified deficits in spatial, social, environmental and economic spheres. The program proposes various projects that will create conditions for further actions. The challenges posed before the revitalization process mean the necessity of undertaking various projects and flexible planning for many years ahead. One of the key actions is a redevelopment of degraded Oława riverfront, which will be an activity and recreation space not only for residents of densely built-up and devoid of green areas Przedmieście Oławskie but also residents of Wroclaw. Modernization of the more than a kilometer section of the wharf can be an impulse for the development of the whole river corridor, that will have high natural, landscape and recreational values. The article discusses the planning process, objectives, principles and methodology of planned activities.

The aim of the study was to determine the contamination transport condition with sediment in the Widawa River, which inflows to the Odra River below Wrocław city. The transport simulations have been performed by means of HEC-RAS model, which was calibrated. Study and geochemical analyses indicate that pollutions are cumulated mainly in sediment of grain size, less than 0,20 mm. It was stated that the main sources of contaminations occurring in the Widawa River bottoms are: superficial run-off, municipal and industrial wastes. Sediment bed quality from the Widawa River in selected cross-sections has been analyzed. Samples of suspended load were collected and divided into eight fractions, for which the phosphorus concentration P was calculated. Deposit particles less than 0,20 mm contained most phosphorus, i.e. 73% (3,52 ppm), and particles greater than 0,20 mm about 27% (1,30 ppm) for the whole sample volume. Relationship between the phosphorus concentration P and the sediment grain size was determined. Analysis showed that the initiation of contamination-sediment suspension in the Widawa River is well described by Engelund criterion. Simulations of the migration of pollutions together with deposits in the Widawa River showed that during average flow discharge, the transport intensity of pollution was equal 2 mg/s, and sediments 6 kg/s. In the present work the water quality of the Widawa River has been also presented.

The main objective of the study was to evaluate if macrophytes structure and trophic status of dam reservoir Kraśnik on a small lowland river Wyżnica are determined by phosphorous loadings. Studies were conducted seasonally in May, July and October during the years 2008-2009. Samples were taken at four sites: Site 1 - inflow of the Wyżnica River to pre-dam, Site 2 − pre-dam, Site 3 − dam reservoir and Site 4 - outflow of the Wyżnica River from dam reservoir. Physical and chemical parameters (temperature, Secchi disc depth, dissolved oxygen, pH, conductivity, total suspension, chlorophyll-a, TP and P-PO4) were measured in water samples. Together with water parameters there were estimated biomass of phytoplankton and species composition and biomass of emergent, floating-leaved and submerged macrophytes. Concentrations of TP, chlorophyll-a and Secchi disc depth were used to calculate trophic state index of Carlsson for dam reservoir and its pre-dam. Based on mean water current, mean residence time of water in dam reservoir and concentrations of TP and P-PO4 loadings (g m-2) flowing into dam reservoir with the Wyżnica River were calculated. The results showed visible negative effect of phosphorous loadings on both macrophytes composition and trophic state of the reservoir. The marked changes concerned soft vegetation. High P loadings (7.74 g m-2 of TP and 6.03 g m-2 P-PO4) during the spring of 2008 caused the disappearance of characeans meadows. In 2009, the presence of rigid hornwort (Ceratophyllum demersum L.), the species typical for eutrophic lakes was noted. This unrooted submerged plant uptakes dissolved orthophosphates directly from the water column.

Values of Carlsson index (51.4 ≤ TSI ≤ 68.2) indicate the eutrophic state of dam reservoir Kraśnik. During summer season in dam reservoir there were observed algal blooms (biomass of phytoplankton exceed 10 mg WW dm-3) and low water transparency (Secchi disc depth ranged from 0.4 to 0.65 m). During the two-year studies in dam reservoir Kraśnik a high reduction of P loadings, mostly dissolved orthophosphates was observed. Dependently on season, reduction of P-PO4 loadings ranged from 52% (July 2008) up to 91% (May 2009). The reduction of TP was lower and reached values from 15% (May 2008) to 48% (July 2009).

The heavy metal release experiments were conducted in the laboratory to examine the effects of 3 factors - pH, dissolved oxygen (DO), and temperature on the metal release from sediments taken from the Huangpu River. The metal concentrations in the dry sediments ranged from 0.030 to 0.296 mg g-1 for Cr, 0.021 to 0.097 mg g-1 for Ni, 0.014 to 0.219 mg g-1 for Cu, 0.035 mg to 0.521 mg g-1 for Zn, 0.0002 to 0.001 mg g-1 for Cd and 0.023 to 0.089 mg g-1 for Pb. Most of the metals found in the sediments were in the form of residual fraction, the exchangeable fraction consisted of only a small portion of total metals. The average dissolved metal concentrations in the overlying water during the 13-day period under different conditions were ranging from 0.82 to 1.93 μg L-1 for Cr, 1.08 to 4.19 μg L-1 for Ni, 40.79 to 82.28 μg L-1 for Cu, 20.30 to 29.96 μg L-1 for Zn, 1.57 to 4.07 μg L-1 for Cd, and 22.26 to 75.50 μg L-1 for Pb, respectively. Statistical interpretation of the data indicated that pH (7, 8, 9), dissolved oxygen DO (1.0 and 5.0 mg L-1) and temperature (4, 16, 25°C) had no significant effects on the heavy metal release under the studied conditions. Cu and Pb had the highest release flux, while Cd, Pb and Cu had higher mobility. The main factors controlling the metals release might be the inherent characters of metals and sediments.

Careful study of river channel hydraulics is helping recover archeological treasures from the bottom of the Vistula River in Warsaw, lost by Swedish looters back in the seventeenth century.

Due to more and more increasing role of pollution surface waters in environment - particularly in populous regions - in this paper the problem of the influence of the town of Nakło city on purity of the Noteć river has been presented. Hydrochemical investigation of the Noteć river in the region of the community Nakło indicated II and III water quality classification. The town of Nakło discharges very much pollution into this river. In spite of recent certain improvement in comparison to 1993-1995 years the annual amount of pollution flowing from the town into the river is still too large and it is 3149 Mg of suspended matter, 266 Mg of nitrogen and 69 Mg of phosphorus.

Structure of fish communities of five small water reservoirs located near the Chodelka river was investigated during the years 2002, 2008 and 2016. In the analyzed water bodies seven fish were noted, representing four families: Cyprinidae (4 species) and Esocidae, Cobitidae, Peri-cidae and Ictaluridae (1 species each). In the structure of collected fish one protected species (M. fossilis) and one alien species (C. auratus gibelio) were presented. Domination structure of ichthyofauna showed considerable differences. Among the dominant species were: R. rutilus (all five reservoir) and C. auratus. The percentage of each fish species in the biomass was slightly different in relation to the structure of domination expressed by the number of identified individuals. Regardless of the reservoir, larger share held: E. lucius, R. rutilus and C. auratus.

Rivers are considered as one of the main resources of water supply for various applications such as agricultural, drinking and industrial purposes. Also, these resources are used as a place for discharge of sewages, industrial wastewater and agricultural drainage. Regarding the fact that each river has a certain capacity for acceptance of pollutants, nowadays qualitative and environmental investigations of these resources are proposed. In this study, qualitative investigation of the Talar river was done according to Oregon Water Quality Index (OWQI), National Sanitation Foundation Water Quality Index (NSFWQI) and Wilcox indicators during 2011–2012 years at upstream, midstream and downstream of the river in two periods of wet and dry seasons. According to the results of OWQI, all of the values at 3 stations and both periods are placed at very bad quality category and the water is not acceptable for drinking purposes. According to NSFWQI, the best condition was related to the upstream station at wet season period (58, medium quality) and the worst condition was related to the downstream in wet season period (46, very bad quality). Also the results of Wilcox showed that in both periods of wet season and dry season, the water quality is getting better from upstream station to the downstream station, and according to the index classification, the downstream water quality has shown good quality and it is suitable for agriculture.

The Timok River (202 km long, 4547 km2 basin area) is located in East Serbia. It is a right tributary of the Danube River and one of the most polluted watercourses in Serbia. On the basis of the data provided by the Republic Hydrometeorological Service of Serbia, the paper presents an analysis of water quality and pollution using the combined physico-chemical WPI index (Water Pollution Index) calculated for two periods - 1993-96 and 2006-2009 at four hydrological stations: Zaječar-Gamzigrad (Crni Timok River), Zaječar (Beli Timok River), Rgotina (Borska Reka River) and Čokonjar (Timok River). The following parameters were taken into consideration: dissolved O2, O2 saturation, pH, suspended sediments, Five Day Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (CODMn), nitrites, nitrates, orthophosphates, ammonium, metals (Cu, Fe, Mn, Hg, Ni, Zn, Cd), sulphates and coliform germs. The average WPI values were calculated for the observed periods based on the comparison of the annual average values of the listed parameters and defined standard values for the I water quality class (according to the Regulation on the Hygienic Acceptability of Potable Water of the Republic of Serbia). The highest pollution degree was recorded in the Borska Reka River, where heavy metal levels (especially manganese and iron) were significantly increased. These metals are indicators of inorganic pollution (primarily caused by copper mining). Also, increased values of the organic pollution indicators (ammonium, coliform germs, Five-Day Biological Oxygen Demand - BOD5) in the Borska Reka and the Timok rivers are the result of uncontrolled domestic wastewater discharge.

The materials mining from rivers have a variety of negative and positive effects. Currently, one of the most important issues in river engineering is the proper management of materials mining. In this research, global experiences and interna-tional standards for managing sand and gravel mining have been applied to evaluate the mining area in the Zohreh River in Khuzestan province (Iran). One of the evaluation methods in this field is the river matrix method. In this method, which is defined on the basis of river pattern, river characteristics such as river size, site location of materials, associated channel and type of deposit are being considered. In this research, a segment of the Zohreh River between Sardasht Zeydun bridge and Mohseniyeh village in which has good potential for gravel mining was selected and evaluated for river characteristics, mining potential and application of river matrix method. The study indicates that the Zohreh River has a braided pattern in the range. The volume of sediment materials in the target area is about 10 000 m3, the length and width of the mining area are 125 and 80 m respectively, and surface extraction with a maximum depth of 1 m was recommended for extraction of materials. At the end of the research, management solutions and solutions for mining of river materials were presented using various standards.

Soil contamination with pesticide and biogenie compounds is a serious problem. The following compounds are detected most often and in largest quantities: lindan, DDT (not used for many years now), Simazine, Atrazine, Chlorfenvinphos and Fenitrothion. The presence of pesticides in surficial waters in the Żuławy Wiślane region has been described many times. Additionally, my own research con finned the presence of pesticides in superficial waters in Podlasie. This paper presents the results of the concentrations determination ofphenoxyacetic herbicides , biogenics and other pollutants in the Białka river. The samples were collected over a period of one year, from April 2000 to March 200 I. The analysis was carried out by reverse phase HPLC and TLC chromatography and colorimetric and spectrophotometric methods by HACH apparatus.

Research concerning chemical constitution of alluvial sediments was done in the lower course of the Obra River (Western Poland). The fragment of vertical profile, which consisted of various alluvial sediments (fine sands, peats and sandy silts) was chosen lor detailed analysis. Main research problem was to determine if lithology and chemical constitution or alluvial deposits arc interconnected in a distinct way within studied section of' the Obra river valley, and if changes of chemical clements concentration could be used to i I lustratc depositional processes which take place in river bed and floodplain. Concentrations ofFe, Mn, Cu, Zn, Ca, Mg and K were determined in collected sediment samples. Investigated changes of chemical clements concentration show that there is a distinct border between the organic sediments, which mark the place of former functioning of the Obra river bed, and sandy silts, which were deposited within floodplain during floods. Besides, dependence between lithologic variability of alluvial sediments and their chemical constitution was observed. However, this dependence is not clear in some cases. The authors concluded that it is necessary to use statistic analyses to define connection between lithology and chemical constitution or alluvial deposits (distinguishing geochemical groups of alluvial sediments).

This study presents the results of investigations, carried out on the Czamiawka River from December 2003 to June 2004. The results indicate the changes of physicochemical parameters of water quality. High concentration of ammonium nitrogen, COD and orthophosphates are probably caused by discharge of municipal waste-water. A drop of ammonium nitrogen, nitrite nitrogen, nitrate nitrogen concentration along the river course is probably caused by inflow of water without these components. High salinity and very high concentration of suspended solids below the "Makoszowy" coal-mine is caused by discharge of coalmine water and carbon dust from coal washer. All of the discussed parameters of water quality (except for pH-index and nitrate nitrogen) are beyond official classification. In comparison to previous analyses a slight improvement of water quality can be observed, especially in the top length. In the estuary water quality deteriorates. Although the Czarniawka River is small, it is one of the most important Kłodnica River contamination sources. Improvement of the existing situation will be possible only if firm waste-water management action will be taken, especially in the "Makoszowy" coal-mine area.

Professor Paweł Rowiński, Vice-President of the PAS and a researcher at the PAS Institute of Geophysics, explains why rivers are such a fascinating subject of study and describes the innovative approach being taken to organizing the IAHR Congress in Poland.

On “blue-green” aspects of climate change adaptation in cities.

This study includes the results of investigations carried out on the Bytomka River which were made from September 2003 to January 2004. The results emphasized the changes of physico-chemical parameters of water quality. Low concentration of dissolved oxygen and high concentration of ammonium nitrogen and COD are probably caused by the discharge of municipal waste-water. High salinity is caused by coal-mines water from the river basin area. All of the discussed parameters of water quality (except for pH-index and nitrate nitrogen) are beyond official classification. Although in the river basin area there are currently activities which protect the environment, no changes of water quality have been observed except for the salinity which is growing up all the time. Improvement of the existing situation will be possible only if firm waste-water managements action is taken.

Research concerning temporal variations of suspended sediment concentration during period of high water stages was done in the lower course of the Obra River near Międzyrzecz (Western Poland). The analysis regarding dependence of mean suspended sediment concentration and discharge allowed to determine the way of suspended sediment supply to the river bed during high water stages. It was supposed that exposures of glacial and fluvioglacial sediments in high concave banks could be an important factor influencing the amount of delivery of suspended material. Besides, normal hysteretic loops (oriented clockwise) were observed in cross-sections 4 and 5. That fact would suggest that transported material originates form the Obra River bed or its vicinity. The process of sediment accretion was observed on a fragment of drowned floodplain during high water stages. Collection of samples of freshly deposited sediment and grain size analysis allowed to illustrate the mechanism of forming floodplain sediments. It also was possible to draw near conditions of forming such sediments in the past.