Rivers In Romania Research Articles

Echo State Network and Sparrow Search: Echo State Network for Modeling the Monthly River Discharge of the Biggest River in Buzău County, Romania

Artificial intelligence (AI) has become an instrument used in all domains with good results. The water resources management field is not an exception. Therefore, in this article, we propose two machine learning (ML) techniques—an echo state network (ESN) and sparrow search algorithm–echo state network (SSA-ESN)—for monthly modeling of the water discharge of one of the biggest rivers in Romania for three periods (S, S1, and S2). In both models, R2 was over 0.989 on the test and training sets and the mean absolute error (MAE) varied between 4.4826 and 7.6038. The performance of the SSA-ESN was similar, but the ESN had the shortest run time. The influence of anomalies on the models’ quality was assessed by running the algorithms on a series without the aberrant values, which were detected by the seasonal hybrid extreme studentized deviate (S-H-ESD) test. The results indicate that removing the anomalies significantly improved both models’ performance, but the run time was increased.

Electrochemical Detection of Glyphosate in Surface Water Samples Based on Modified Screen-Printed Electrodes.

This study addresses the necessity to monitor the presence of glyphosate (Gly) in waters, highlighting the need for on-site detection of Gly by using electrochemical sensors in environmental and agricultural monitoring programs. Two approaches were employed: (1) modification with graphene decorated with gold nanoparticles (AuNPs-Gr) and dispersed in either dimethylformamide (DMF) or a solution containing Nafion and isopropanol (NAF), and (2) molecularly imprinted polymers (MIPs) based on polypyrrole (PPy) deposited on gold SPEs (AuSPE). Electrochemical characterization revealed that sensors made of AuNPs-Gr/SPCE exhibited enhanced conductivity, larger active area, and improved charge transfer kinetics compared to unmodified SPEs and SPEs modified with graphene alone. However, the indirect detection mechanism of Gly via complex formation with metallic cations in AuNPs-Gr-based sensors introduces complexities and compromises sensitivity and selectivity. In contrast, MIPPy/AuSPE sensors demonstrated superior performance, offering enhanced reliability and sensitivity for Gly analysis. The MIPPy/AuSPE sensor allowed the detection of Gly concentrations as low as 5 ng/L, with excellent selectivity and reproducibility. Moreover, testing in real surface water samples from the Olt River in Romania showed recovery rates ranging from 90% to 99%, highlighting the effectiveness of the detection method. Future perspectives include expanding the investigation to monitor Gly decomposition in aquatic environments over time, providing insights into the decomposition's long-term effects on water quality and ecosystem health, and modifying regulatory measures and agricultural practices for mitigating its impact. This research contributes to the development of robust and reliable electrochemical sensors for on-site monitoring of Glyphosate in environmental and agricultural settings.

Methodology to evaluate the effectiveness of hydromorphological restoration of rivers in Romania

In the context of the requirements of the Water Framework Directive to reinstate a river’s good ecological status after being severely altered by human pressures, river restoration became a major topic in the last decade in the EU and the number of projects implemented especially on hydromorphology increased. However, it is still uncertain whether these restoration measures have positive cumulative effects, i.e. hydromorphological effectiveness, when compared to reference conditions and expectations of stakeholders, because of inconsistent methodologies. Therefore, the goal of our project is to develop a methodology to evaluate the hydromorphological effectiveness of river restoration, based on standardised indicators, at various spatial scales, appropriate for implemented measures and for restored river types, weighting the expectations of actors and adapted to case studies in Romania. This methodological protocol could become also a useful tool to create a strategy and make decisions in the practice of river restoration. Moreover, this kind of analysis could contribute to clarifying the issue of standards in environmental projects.

Mountains of plastic: Mismanaged plastic waste along the Carpathian watercourses

Plastic waste poses numerous risks to mountain river ecosystems due to their high biodiversity and specific physical characteristics. Here, we provide a baseline assessment for future evaluation of such risks in the Carpathians, one of the most biodiverse mountain ranges in East-Central Europe. We used high-resolution river network and mismanaged plastic waste (MPW) databases to map MPW along the 175,675 km of watercourses draining this ecoregion. We explored MPW levels as a function of altitude, stream order, river basin, country, and type of nature conservation in a given area. The Carpathian watercourses below 750 m a.s.l. (142,282 km, 81 % of the stream lengths) are identified as significantly affected by MPW. Most MPW hotspots (>409.7 t/yr/km2) occur along rivers in Romania (6568 km; 56.6 % of all hotspot lengths), Hungary (2679 km; 23.1 %), and Ukraine (1914 km; 16.5 %). The majority of the river sections flowing through the areas with negligible MPW (< 1 t/yr/km2) occur in Romania (31,855 km; 47.8 %), Slovakia (14,577 km; 21.9 %), and Ukraine (7492; 11.2 %). The Carpathian watercourses flowing through the areas protected at national level (3988 km; 2.3 % of all watercourses studied) have significantly higher MPW values (median = 7.7 t/yr/km2) than those protected at regional (51,800 km; 29.5 %) (median MPW = 1.25 t/yrkm2) and international levels (66 km; 0.04 %) (median MPW = 0 t/yr/km2). Rivers within the Black Sea basin (88.3 % of all studied watercourses) have significantly higher MPW (median = 5.1 t/yr/km2, 90th percentile = 381.1 t/yr/km2) than those within the Baltic Sea basin (median = 6.5 t/yr/km2, 90th percentile = 84.8 t/yr/km2) (11.1 % of all studied watercourses). Our study indicates the locations and extent of riverine MPW hotspots in the Carpathian Ecoregion, which can support future collaborations between scientists, engineers, governments, and citizens to better manage plastic pollution in this region.

River Sand and Gravel Mining Monitoring Using Remote Sensing and UAVs

The development of methodologies for analyzing the evolution and pressures exerted on the river channel network is one of the main concerns of researchers today. The assessment of natural or artificial changes of river channels and beds plays an important role in environmental protection, but also in the implementation of integrated water resource management plans. Given the episodic and dynamic nature of river bank and bed erosion, along with the difficulty of reaching certain reaches, a methodological approach that uses aerial imagery, initially from satellite sources and afterwards from unmanned aerial vehicles, is proposed. This approach was utilized in a perennial river in Romania but also in an ephemeral torrent channel in Greece, in order to test the prevalent types of hydrographic network in the Mediterranean and Black Sea region. The methodology used was able to identify the location and the volume of the bed material extracted and the time frame in which it occurred. These encouraging results showcase an accurate but also relevantly low-cost monitoring method for illegal anthropogenic activities that can be easily adopted by the responsible authorities. The adoption of the method will contribute to the more efficient monitoring of river protection, by accurately and timely identifying areas of illegal river bed extraction that will enable authorities to enforce European Union and national legislation.

Post-Construction, Hydromorphological Cumulative Impact Assessment: An Approach at the Waterbody Level Integrating Different Spatial Scales

The environmental impact assessment is a process required in many countries. It highlights future activities with a significant impact on the environment. Water, as an environmental factor, needs adequate methods for quantifying cumulative impact of hydrotechnical works. In most cases, for new developments, baseline data is collected before the beginning of the construction, but for waterworks already in place, a different approach is needed. In line with the EU Water Framework Directive (Directive 2000/60/EC), the overall purpose of the research is to develop an approach for the hydromorphological cumulative impact assessment integrating different spatial scales for existing water intakes with transversal barriers on mountain rivers in Romania. Being a research study developed for a specific issue—post-construction impact assessment, some innovative actions were required. Lack of information in the pre-construction phase was an important constraint. Customizing formulas of certain indicators established within the Romanian method for hydromorphological status assessment of rivers proved to be a practical solution to show both local and waterbody hydromorphological impact. Upscaling the impact from the local scale to the river sector and the waterbody allows awareness of the spatial extent of the impact and understanding of the importance of the thresholds of significant impact for a broader audience. In order to better highlight the approach, this paper shows practical examples. The whole chain of the drivers–pressures–state–impacts–responses (DPSIR) framework is applied in the case of two river water bodies with hydropower generation facilities in place. In addition, some recommendations for actions are provided.

Establishing Legal &amp;lt;i&amp;gt;Force Majeure&amp;lt;/i&amp;gt; Case for the Interruption of Hydro Energy Supply Related to an Extreme Hydrological Drought Event

The management of water resources and specifically the energy supply from hydropower systems are strongly affected by drought events. This paper is devoted to the unfolding of legal consequences caused by an extreme hydrological drought event. The legal litigation occurred when – due to a severe deficit of water – the hydropower company that manages the hydro energy resources over the entire territory of Romania was unable to deliver the amount of electricity stipulated in the power purchase agreements. The studypresents an extensive statistical analysis of extreme hydrological drought events occurrence, using the threshold level method. The statistical analysis was applied on large historical records of the flow rates (50-90 years) and revealed the occurrence of extreme drought events, i.e. extremely low occurrence frequency phenomena. The characteristics of the historical data were studied to highlight the area where the forecast normally used in the hydro generation planning is not possible. In order to evaluate the occurrence of extreme drought phenomena, the natural monthly and annually flows of the Danube and other seven major interior rivers in Romania (Argeș, Bistrița, Olt, Lotru, Sebeș, Someș, Siret and Raul Mare) were analyzed, reflecting fairly a general picture of the flow distribution on the entire territory. The analyzed cases refer to periods when – due to a severe deficit of water – the Romanian hydropower company was unable to generate electricity according to the power purchase agreements (PPA). The results of the statistical analysis were further used as the base for the legal cases that confirmed the <i>force majeure </i>situations claimed by the hydropower company.

Occurrence and Fate of Bisphenol A and its Congeners in Two Wastewater Treatment Plants and Receiving Surface Waters in Romania.

The present study investigated the distribution and environmental fate of Bisphenol A (BPA), the 4-hydroxyacetophenone (4-HAP) metabolite, and 5 other bisphenol congeners in 2 municipal wastewater treatment plants (WWTPs) and their receiving rivers in Romania. Accordingly, a new, highly sensitive and accurate solid-phase extraction-liquid chromatography-electrospray ionization-tandem mass spectrometry method was developed and validated. This technique generated low limit of quantitation values: below 2.3 ng/L for surface water and less than 2.4 and 2.7 ng/L for WWTP effluent and influent water. The sum of detected analytes in wastewater was between 1337 and 16 118 ng/L for influent samples and between 15 and 96 ng/L for effluent samples. In surface water, the total of all compounds was somewhere between 34 and 240 ng/L. The highest concentration observed was for BPA in all 3 types of analyzed water (up to 9140 ng/L for influent, as high as 75 ng/L for effluent, and a maximum of 135 ng/L in surface waters). All analyzed samples were free of bisphenols B, C, and F. For all analytes detected in surface water, the concentration values were higher than those determined in the effluent samples, which may be caused by intrinsic contamination of the 2 rivers (Danube and Jiu Rivers). Values of environmental risk coefficients, calculated for both effluents and surface waters, indicated a low ecological risk or no ecological risk for 3 types of organisms (algae, daphnia, and fish). Human risk assessment calculation suggests no risk to human health as a result of the presence of BPA in either of the 2 rivers. Environ Toxicol Chem 2021;40:435-446. © 2020 SETAC.

Defining ecological status of phytobenthos in very large rivers: a case study in practical implementation of the Water Framework Directive in Romania

Establishing ecological assessment schemes is challenging when gradients are short and there are no sites with minimal anthropogenic alteration against which metrics can be calibrated. This is the situation for large rivers in Romania and this paper describes efforts to establish meaningful ecological status concepts. The intercalibration exercise, conducted as part of Water Framework Directive (WFD) implementation, has provided a metric (“phytobenthos Intercalibration Common Metric“, pICM) which allows ecological status in different countries to be expressed on a common scale. The average boundary positions of countries who participated in this exercise provided a “common view” of status and, together with pICM, offer an “off-the-shelf” solution for countries unable to develop independent methods. However, even when expressed as pICM, Romanian phytobenthos data have a weak relationship with nutrients. Analysis of chemical data and comparison with similar data from elsewhere in Europe confirm that there are few sites with significantly elevated nutrient concentrations. Incorporation of the Romanian data into the larger dataset produced a stronger relationship from which the status of phytobenthos in very large rivers in Romania could be confirmed. This paper shows how the consensus that emerged from the WFD intercalibration exercise supports those countries unable to participate in the initial exercises.

Modeling Hydrodynamic Changes Induced by Run-of-River Hydropower Plants along the Prahova River in Romania

AbstractThe purpose of the study is to reveal changes of the hydrodynamics and sediment transport induced into the river channel by the operation of small hydropower plants (SHPs). A 36-km reach of...

Watershed Sustainability Index Development and Application: Case Study of the Motru River in Romania

Watershed Sustainability Index Development and Application: Case Study of the Motru River in Romania

Analysis of emerging organic contaminants in water, fish and suspended particulate matter (SPM) in the Joint Danube Survey using solid-phase extraction followed by UHPLC-MS-MS and GC–MS analysis

In the third Joint Danube Survey (JDS3), emerging organic contaminants were analysed in the dissolved water phase of samples from the Danube River and its major tributaries. Analyses were performed using solid-phase extraction (SPE) followed by ultra-high-pressure liquid chromatography triple-quadrupole mass spectrometry (UHPLC-MS-MS) and gas chromatography–mass spectrometry (GC–MS). The polar organic compounds analysed by UHPLC-MS-MS were 1H-benzotriazole, methylbenzotriazoles, carbamazepine, 10,11-dihydro-10,11-dihydroxy-carbamazepine, diclofenac, sulfamethox-azole, 2,4-D (2,4-dichlorophenoxyacetic acid), MCPA (2-methyl-4-chlorophenoxyacetic acid), metolachlor, cybutryne (irgarol), terbutryn, DEET (N,N-diethyl-m-toluamide), and several perfluoroalkyl acids (C6–C9; C8=perfluorooctanoic acid (PFOA)) and perfluorooctansulfonic acid (PFOS). In addition, several organophosphorus flame retardants were analysed by GC-MS. The most relevant compounds identified in the 71 water samples, in terms of highest median and maximum concentrations, were 1H-benzotriazole, tris(1-chloro-2-propyl)phosphate (TCPP), methylbenzotriazoles, carbama-zepine and its metabolite, DEET, sulfamethoxazole, tris(isobutyl)phosphate (TiBP), tris(2-chloroethyl)phosphate (TCEP), PFOA, PFOS and diclofenac. The concentrations of these compounds in the samples were generally below the environmental quality standard (EQS) threshold values, with the exception of PFOS, the concentration of which exceeded the annual average water EQS limit of 0.65ng/L along the whole river, and also exceeded the fish biota EQS of 9.1μg/kg. In addition, the proposed EQS for diclofenac, of 0.1μg/L, was exceeded in the Arges River in Romania (255ng/L).

Assessing the Operation of the Cooling Water System of a Hydro-Power Plant Using EPANET

This paper focuses on the Cooling Water System (CWS) of Vidraru Hydro-Power Plant (HPP) − a 220 MW underground HPP, on the Arges River in Romania. It is equipped with 4 high head vertical Francis turbines of 55 MW each, 4 hydropower generators of 61 MVA each, and 7 step-up transformers of 40 MVA each. The goal is to model the above CWS and to analyse the system response under normal and critical operating scenarios. The numerical model built in EPANET is complex: the cooling water network is normally fed by pumping from the underground tailrace (using up to 3 pumps of 110kW each), but there is a backup supplying circuit fed directly from the penstock bifurcation pipe (using pressure reducing valves). Within the power plant, the following equipments need cooling water: air-water heat exchangers (related to generators and HVAC system); oil-water heat exchangers (related to bearings, speed governors and transformers); coolers of the turbines seals. Since EPANET lacks such physical components, they are artificially replaced by throttle control valves set with equivalent loss coefficients, established upon pressure drop values available for each equipment. The computed flow rate and pressure values match the existing recordings for normal operation. The numerical model also provides data on the system behaviour under critical operation conditions, e.g. when the HPP is operating at full capacity with CWS fed only by 2 pumps, out of 3 available pumps.

Age Structure and Growth Dynamics of European Chub, Squalius cephalus, Linnaeus 1758 (Actinpterygii: Cyprinidae) from two Catchments in Transylvania-Romania

In recent years, research on water monitoring involves more and more the analysis of ichtyofauna in many aspects such as: the number of fish species, their distribution in the catchment sectors, the ratio between them, the dominant species, and growth dynamics and age structure of fish populations. The chub (Squalius cephalus), is in this case an indicator species. It is present in most rivers in Romania and it is well represented numerically. The specimens for our study were collected from the Someşul Mic River (Cluj County) respectively Târnava (Alba County). Growth dynamics in this case is a comparison tool, perfect for fish populations. Age category distribution from the catchments taken into study is also a tool that gives us important information. The absence of some age categories is a question mark related to environmental accidents that occurred on a river or river sector. Through this study, we intend to demonstrate that growth dynamics and age structure are effective tools for characterizing and comparing fish populations.

Infections with Gyrodactylus spp. (Monogenea) in Romanian fish farms: Gyrodactylus salaris Malmberg, 1957 extends its range.

BackgroundThe salmon parasite Gyrodactylus salaris Malmberg, 1957 has caused high mortalities in many Atlantic salmon, Salmo salar, populations, mainly in Norway. The parasite is also present in several countries across mainland Europe, principally on rainbow trout, Oncorhynchus mykiss, where infections do not seem to result in mortalities. There are still European countries where there are potential salmonid hosts for G. salaris but where the occurrence of G. salaris is unknown, mainly due to lack of investigations and surveillance. Gyrodactylus salaris is frequently present on rainbow trout in low numbers and pose a risk of infection to local salmonid populations if these fish are subsequently translocated to new localities.MethodsFarmed rainbow trout Oncorhynchus mykiss (n = 340), brook trout, Salvelinus fontinalis (n = 186), and brown trout, Salmo trutta (n = 7), and wild brown trout (n = 10) from one river in Romania were sampled in 2008 and examined for the presence of Gyrodactylus spp. Alltogether 187 specimens of Gyrodactylus spp. were recovered from the fish. A subsample of 76 specimens representing the different fish species and localities were subjected to species identification and genetic characterization through sequencing of the ribosomal internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome c oxidase subunit 1 (cox1).ResultsTwo species of Gyrodactylus were found, G. salaris and G. truttae Gläser, 1974. This is the first time G. salaris is diagnosed in Romania. Gyrodactylus salaris was found to infect rainbow trout, brown trout and brook trout in eight of the 12 farms examined. The prevalence and intensity of infections were generally low in all farms. Gyrodactylus truttae was present on brook trout in one farm and on wild brown trout in the river studied. This also represents the first record of this parasite in Romania. Analyses of sequences of the cox1 gene of G. salaris from Romania revealed four haplotypes, all previously undescribed. While it is not unlikely that the infections in Romanian fish farms originate directly from imported rainbow trout, the current data is not sufficient to conclude on this and does not exclude that the infections can originate from hosts in the local water systems. The study shows that there are still unknown populations and variants (haplotypes) of G. salaris present in European rainbow trout aquaculture, all or many of them with unknown biological characteristics such as host specificity and virulence. As some strains might be pathogenic to Atlantic salmon, the importance of carrying out surveillance and keeping a high focus on control with import and export of live fish for aquaculture purposes is important.ConclusionsGyrodactylus salaris and G. truttae are for the first time found on salmonids in Romania. All mitochondrial haplotypes recovered were previously undescribed and this indicates that there is still an unknown diversity of this parasite present in localities not previously examined. The virulence of the haplotypes found in Romania is unknown and requires establishing.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1727-7) contains supplementary material, which is available to authorized users.

Numerical Simulation of the Cooling Water System of a 115 MW Hydro-Power Plant

The present case study points on the cooling water system of the Hydro-Power Plant (HPP) Bradisor, on the Lotru River in Romania. This 115 MW underground power plant is equipped with two Francis turbines. We built in EPANET a numerical model to simulate the operation of the cooling water system of this HPP, for different working scenarios. The whole hydraulic system is a complex one: it is composed of a main cooling water network fed by pumps, a water-based fire fighting network for the hydropower generators and a backup cooling water network fed from the penstock pipes. The numerical model of the whole cooling water system consists of 87 pipes, 133 junctions, 6 variable speed driven centrifugal pumps, 59 valves and 3 reservoirs. Some throttle control valves (TCV) are artificially inserted in our numerical model and are set with appropriate loss coefficients values to be equivalent to the equipments that introduce minor losses in the system and don’t exist as physical components in EPANET. Those equipments are: air-water heat exchangers (placed around the hydropower generators), oil-water heat exchangers (of heavy-duty thrust bearings, of turbines’ and generators’ guide bearings, of the 130 MVA step-up transformer), coolers of turbines’ seals and self-cleaning filters (one for each hydropower unit and another one for the transformer). The loss coefficient for each equivalent TCV was set based on pressure loss values measured in situ on each equipment. The numerical results (pressure and flow rate values) match the existing recordings. The simulations prove that by using a proper calibration of the numerical model, EPANET capabilities can be extended for more complex systems than the water distribution systems.

Water Quality Management of the Waters of the Romanian River Hârtibaciu

This study aims at monitoring physico-chemical features of the waters of the Hârtibaciu River in Romania with a view to establishing its qualitative benchmarks. Using the waters of this river for agricultural purposes leads to the establishment of its physical and chemical features and its falling within the related quality group. This study has monitored general chemical indicators and specific chemical indicators in the waters of the Hârtibaciu River; the resulting values show that it falls within the 2nd/3rd quality group.

Water Quality Management of the Waters of the Romanian River Hârtibaciu

This study aims at monitoring physico-chemical features of the waters of the Hârtibaciu River in Romania with a view to establishing its qualitative benchmarks. Using the waters of this river for agricultural purposes leads to the establishment of its physical and chemical features and its falling within the related quality group. This study has monitored general chemical indicators and specific chemical indicators in the waters of the Hârtibaciu River; the resulting values show that it falls within the 2nd/3rd quality group.

Aspects Concerning the Processing of Observations in Support Networks Related to Hydropower Objectives

Models for processing geodetic observations made in support networks related to hydropower objectives are the ones used in general geodetic networks. For geodetic observations processing, based on the type of measurements made, are used mathematical models corresponding to indirect and conditioned measurements of same precision or different precision. The purpose of this paper is to highlight some aspects regarding the importance of using mathematical models for processing observations in support networks related to hydropower objectives. The case study concerning the geodetic observations processing of support networks related to hydropower objectives wasmade on the arrangements from the superior part of Someș Cald river in Romania. The geodetic observations carried out in the support network were made using the total station Leica TM 30 and for processing were used the mathematical models which were previously mentioned. The accuracy of determining the coordinates of the support network is conditioned by the measurement accuracy and by the mathematical model which was used in processing. After determining the stability of the network points we could conclude that the parameter values obtained by the method of conditional measurements are substantially equal to those determined from indirect measurements. The displacement values obtained through the matrix and Gauss-Doolittle method are identical, which shows the correctness of calculations. Also the standard deviation of the most probable values is below millimeter. The biggest displacements are registered at point PIV, for which it should not be used for determining the displacement of the tracking marks placed on the dam.

Isotopic fingerprint of the middle Olt River basin, Romania

One of the most important tributaries of the Danube River in Romania, the Olt River, was characterized in its middle catchment in terms of the isotopic composition using continuous flow–isotope ratio mass spectrometry (CF–IRMS). Throughout a period of 10 months, from November 2010 to August 2011, water samples from the Olt River and its more important tributaries were collected in order to investigate the seasonal and spatial isotope patterns of the basin waters. The results revealed a significant difference between the Olt River and its tributaries, by the fact that the Olt River waters show smaller seasonal variations in the stable isotopic composition and are more depleted in 18O and 2H. The waters present an overall enrichment in heavy isotopes during the warm seasons.