The development of dams alters the structure and function of river ecosystems. Dam reservoirs have an impact on flow regime, sediment transport, and water quality. Damming a river decreases water velocity, which leads to an increase in suspended sediments deposition. Reservoirs often are described as water treatment plants because they trap water contaminants and suspended sediments. Suspended sediments are the principal factor for heavy metals transport [1][2]. Human activity increased input of heavy metals to water bodies where sediments are deposited [3][4][5][6][7][8]. Amin et al. [9] and Zheng et. al. [10] reported that more than 90% of the heavy metal load in the water bodies has been associated with suspended particulate matter and sediments. The spatial and seasonal variations of heavy metal loads are controlled by suspended sediment concentrations as well as water pH, which controls the absorbance of heavy metals [11].The spatial distribution of sediments in a reservoir is not uniform [12]. Toward the dam, sediments are usually more fine-grained and lithologically uniform [13]. The heavy metals concentrations generally increased with the decrease of particle size and increase of organic matter. The concentration of heavy metals in Pol. AbstractThe aim of this study was to analyze the heavy metals transport in a river-reservoir system. Sediment samples from 25 locations (9 from the Powa River and 16 from the Stare Miasto Reservoir) were analyzed for trace metals contents (Cr, Ni, Cu, Zn, Cd, and Pb). The relationships between heavy metal concentrations and bottom sediment physical properties were determined with the use of the multivariate statistical techniques cluster analysis (CA), principal component analysis (PCA), and canonical correspondence analysis (CCA). The results showed that concentrations of heavy metals in the sediments of the reservoir were higher than those in the bottom sediments of the river. Concentrations of heavy metals in bottom sediments in the river above the reservoir were characterized by lower spatial variability. Decisive influence on heavy metal concentrations of bottom sediments had silt, clay, and total organic matter content.
Abstract:The main concern of the study was the evaluation of the impact of new investment in road infrastructure on the flood hazard. The flood hazard is considered here on the basis of maps according to requirements of EU Flood Directive. The analyses presented were made for the Warta river, near the town of Wronki. The procedure included data collection and processing, model configuration, hydraulic simulation, generation of water surface profiles, and flood hazard maps. The ArcGIS tools, as well as HEC-RAS package, were used in this research. The model recalibration described in the paper provided excellent results according to independent criteria. Hence, the results obtained may be considered as valid. Finally the results reconstructing the conditions with and without the bridge are compared. The assessed impact of the bridge seems to be moderate, but the procedure proposed in the presented paper may be of wider application. In view of the EU Flood Directive and plans for investments in road infrastructure, the methodology presented seems very attractive.
The paper presents the problems related to the functioning of reservoirs in the Wielkopolska province and suggests their possible solutions. The reservoirs chosen as examples include typical dam constructions with a single water body (Jeziorsko, Rydzyna), two water body objects with separated preliminary part (Stare Miasto, Kowalskie, Radzyny) and lateral constructions (Pakosław, Jutrosin). The reservoirs were built in period from 1970 to 2014. They differ in construction, functions and water management rules. Analysis of the main problems related to the reservoir functioning is aimed at finding ways of improving the construction of new reservoirs that would satisfy increasingly stringent environmental and legal restrictions and the methods of water management in the reservoirs. On the basis of a questionnaire filled in by the reservoir operators, the main problem is water quality. Especially the huge inflow of biogenic compounds causes blooms of algae and overgrowth with riparian vegetation. Some difficulties are also related to management of the reservoirs of multipurpose operation. It is difficult to take into account the requirements of environmental flow maintenance, flood protection, water supply for agriculture and water use for tourism and recreation and hydropower generation, etc.
Abstract:The purpose of the paper is to test forecasting of the sediment transport process, taking into account two main uncertainties involved in sediment transport modeling. These are: the lack of knowledge regarding future flows, and the uncertainty with respect to which sediment transport formula should be chosen for simulations. The river reach chosen for study is the outlet part of the Ner River, located in the central part of Poland. The main characteristic of the river is the presence of an intensive morphodynamic process, increasing flooding frequency. The approach proposed here is based on simulations with a sediment-routing model and assessment of the hydraulic condition changes on the basis of hydrodynamic calculations for the chosen characteristic flows. The data used include Digital Terrain Models (DTMs), cross-section measurements, and hydrological observations from the Dabie gauge station. The sediment and hydrodynamic calculations are performed using program HEC-RAS 5.0. Twenty inflow scenarios are of a 10-year duration and are composed on the basis of historical data. Meyer-Peter and Müller and Engelund-Hansen formulae are applied for the calculation of sediment transport intensity. The methodology presented here seems to be a good tool for the prediction of long-term impacts on water surface profiles caused by sediment deposition and erosion.
The purpose of the presented research is analysis and assessment of the Stare Miasto reservoir impact on the hydrological regime changes of the Powa River. The reservoir was built in 2006 and is located in the central part of Poland. The total area of inundation in normal conditions is 90.68 ha and its capacity is 2.159 mln m3. Hydrological regime alteration of the Powa River is analysed on the basis of daily flows from the Posoka gauge station observed during period 1974–2014. Assessment of hydrological regime changes is carried out on the basis of Range of Variability Approach (RVA) method. All calculations are made by means of Indicators of Hydrologic Alteration (IHA) software version 7.1.0.10. The analysis shows that the Stare Miasto reservoir has a moderate impact on hydrological regime of the Powa River. Construction of the reservoir has positive effect on stability of minimal flows, which are important for protection of river ecosystems. The results obtained indicate that the Stare Miasto reservoir reduces a spring peak flow and enables to moderate control of floods.
In this paper, the impact of maximum flow uncertainty on flood hazard zone is analyzed. Two factors are taken into account: (1) the method for determination of maximum flows and (2) the limited length of the data series available for calculations. The importance of this problem is a consequence of the implementation of the EU Flood Directive in all EU member states. The factors mentioned seem to be among the most important elements responsible for potential uncertainty and inaccuracy of the developed flood hazard maps. Two methods are analyzed, namely the quantiles method and the maximum likelihood method. The maximum flows are estimated for the Wronki gauge station located in the reach of the Warta river. This simple river system is located in the central part of Poland. The length of the available data is 44 years. Hence, the series of the lengths 40, 30 and 20 years are tested and compared with reference calculations for 44 years. The hydrodynamic model HEC-RAS is used to calculate water surface profiles in steady state flow. The Python scripting language is applied for automation of HEC-RAS calculations and processing of final results in the form of inundation maps. The number of trials for each factor is not huge to keep the presented methodology useful in practice. The chosen measure of uncertainty is the range of variability for maximum flow values as well as inundation areas. The estimated values stressed the great importance of the factors analyzed for the uncertainty of the maximum flows as well as inundation areas. The impact of the data series length on the maximum flows is straightforward; a shorter data series gives a wider range of variability. However, the dependencies between other factors are more complex. Hence, the application of methodology based on the simulation and GIS data processing for assessment of this problem seems to be quite a good approach.
Streszczenie. Celem przestawionej publikacji jest analiza warunków przepływu oraz pracy budowli wodnych usytuowanych na odcinku Noteci Bystrej od stopnia Romanowo do jazu w Rosku. Obiekt badawczy zostały wybrany z dwóch powodów: (1) dla tego odcinka rzeki Noteć zostały opracowane mapy zagrożenia powodziowego jako wdrożenie Dyrektywy Powodziowej UE w ramach prac nad projektem ISOK, (2) na wymienionym odcinku znajduje się szereg budowli piętrzących posiadających zdolność retencjonowania wody i oddziaływania na falę wezbraniową. W ramach badań wykorzystano szeroko narzędzia GIS oraz modelowania matematycznego. Słowa kluczowe: Noteć Bystra, HEC-RAS, symulacja przepływu, budowla hydrotechniczna WSTĘP Istotą problemu poruszonego w niniejszej pracy jest analiza zmian funkcjonowania wybranych stopni wodnych na Noteci Bystrej. Badania zostały wykonane za pomocą modelu jednowymiarowego umożliwiającego symulację przepływu wezbraniowego w korycie rzecznym. Testowano różne warianty pracy budowli na przykładzie fal hipotetycznych o określonym prawdopodobieństwie przewyższenia. W badaniach wykorzy
The paper presents the results of changes in the physicochemical status of the water of the river Ner in the Dąbie profile, observed in the period 2000-2006. The river Ner flows through the lowland in central part of Poland and its basin area is 1835 km 2. The physicochemical status of the river water was evaluated on the basis of 16 parameters characterising the physical state, oxygen condition, organic pollution, salinity and acidity. The results of a series of analyses performed over 6 years provided the evidence that the extension of sewage system and enlargement and upgrading of the sewage treatment plant have had positive effect on the state of water in the river Ner. The oxygen conditions have improved and the loading with organic substances from insufficiently purified sewage has decreased. The level of the water salinity has increased.
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