Search results for: István Gábor Hatvani

Items from 1 to 19 out of 19 results

article

The Application of Magnetic Resonance Imaging (Mri) to the Examination of Plant Tissues and Water Barriers

Pál Jakusch, Tímea Kocsis, Ilona Kovácsné Székely, István Gábor Hatvani

Acta Biologica Hungarica > 2018 > 69 > 4 > 423-436

The aim of the present study is to extend the applicability of MRI measurements similar to those used in human diagnostics to the examination of water barriers in living plants, thus broadening their use in natural sciences. The cucumber, Cucumis sativus, and Phillyrea angustifolia, or false olive, were chosen as test plants. The MRI measurements were carried out on three samples of each plant in...

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Periodic signals of climatic variables and water quality in a river – eutrophic pond – wetland cascade ecosystem tracked by wavelet coherence analysis

István Gábor Hatvani, Adrienne Clement, János Korponai, Zoltán Kern, more

Ecological Indicators > 2017 > 83 > C > 21-31

Lakes are sensitive to changes in their environmental boundary conditions that can be indicated in the periodic behavior of water quality variables. The present work aims to assess the degree to which common annual periodic behavior is present (1994–2010) in the meteorological parameters (global radiation, air temperature, cloud cover), streamflow; and five primary nutrients (e.g. total phosphorus,...

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Investigation of the climate-driven periodicity of shallow groundwater level fluctuations in a Central-Eastern European agricultural region

Tamás Garamhegyi, József Kovács, Rita Pongrácz, Péter Tanos, more

Hydrogeology Journal > 2018 > 26 > 3 > 677-688

The distribution and amount of groundwater, a crucial source of Earth’s drinking and irrigation water, is changing due to climate-change effects. Therefore, it is important to understand groundwater behavior in extreme scenarios, e.g. drought. Shallow groundwater (SGW) level fluctuation under natural conditions displays periodic behavior, i.e. seasonal variation. Thus, the study aims to investigate...

article

Geostatistical analysis and isoscape of ice core derived water stable isotope records in an Antarctic macro region

István Gábor Hatvani, Markus Leuenberger, Balázs Kohán, Zoltán Kern

Polar Science > 2017 > 13 > C > 23-32

Water stable isotopes preserved in ice cores provide essential information about polar precipitation. In the present study, multivariate regression and variogram analyses were conducted on 22 δ²H and 53 δ¹⁸O records from 60 ice cores covering the second half of the 20th century. Taking the multicollinearity of the explanatory variables into account, as also the model's adjusted R² and its mean absolute...

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The role of annual periodic behavior of water quality parameters in primary production – Chlorophyll-a estimation

József Kovács, Péter Tanos, Gábor Várbíró, Angéla Anda, more

Ecological Indicators > 2017 > 78 > C > 311-321

Since phytoplankton is an autochthonous primary producer, it plays a vital role in driving the water quality of rivers and lakes. Therefore, in cases where measurements are lacking, its estimation is of the essence. In the present study, Morlet wavelet spectrum (periodicity) and multiple regression analyses were conducted on 15 chemical, biological and physical water quality variables sampled at 14...

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Developments in water quality monitoring and management in large river catchments using the Danube River as an example

Deborah V. Chapman, Chris Bradley, Gretchen M. Gettel, István Gábor Hatvani, more

Environmental Science & Policy > 2016 > 64 > C > 141-154

Effective management of water quality in large rivers requires information on the influence of activities within the catchment (urban and rural) throughout the whole river basin. However, traditional water quality monitoring programmes undertaken by individual agencies normally relate to specific objectives, such as meeting quality criteria for wastewater discharges, and fail to provide information...

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Natural proxy records of temperature- and hydroclimate variability with annual resolution from the Northern Balkan–Carpathian region for the past millennium – Review & recalibration

Zoltán Kern, Alexandra Németh, Margit Horoszné Gulyás, Ionel Popa, more

Quaternary International > 2016 > 415 > C > 109-125

A systematic compilation of temperature (n = 10) and moisture sensitive (n = 4) proxy records of the Northern Balkan–Carpathian (NBC) region with annual resolution for the past millennium is presented and evaluated. The proxy-climate relationship is re-evaluated using a uniform climatological dataset providing a longer calibration. The originally determined response seasons were in the most part verified...

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Assessing the relationship of background factors governing the water quality of an agricultural watershed with changes in catchment property (W-Hungary)

István Gábor Hatvani, József Kovács, László Márkus, Adrienne Clement, more

Journal of Hydrology > 2015 > 521 > C > 460-469

With urbanization and the growth of agriculture, the importance of precisely assessing the contribution of diffuse- and point source loads arriving to surface waters is becoming more and more important. Determining their effects, however, is not as straightforward as it at first seems. The main aim of the study was to determine the driving background factors of a river located in an agricultural watershed,...

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Spatial Optimization of Monitoring Networkson the Examples of a River, a Lake-Wetland System and a Sub-Surface Water System

József Kovács, Solt Kovács, István Gábor Hatvani, Norbert Magyar, more

Water Resources Management > 2015 > 29 > 14 > 5275-5294

Monitoring systems in general have to meet numerous requirements, the most important of which are representativeness and cost efficiency. The aim of the study, therefore, was to present the spatial optimization of the monitoring networks of a river (the Danube), a wetland-lake system (Kis-Balaton & Lake Balaton), and a sub-surface water system in the watershed of Lake Neusiedl/Fertő over a period...

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Optimization of the monitoring network on the River Tisza (Central Europe, Hungary) using combined cluster and discriminant analysis, taking seasonality into account

Péter Tanos, József Kovács, Solt Kovács, Angéla Anda, more

Environmental Monitoring and Assessment > 2015 > 187 > 9 > 1-14

The most essential requirement for water management is efficient and informative monitoring. Operating water quality monitoring networks is a challenge from both the scientific and economic points of view, especially in the case of river sections ranging over hundreds of kilometers. Therefore, spatio-temporal optimization is vital. In the present study, the optimization of the monitoring system of...

article

Classification into homogeneous groups using combined cluster and discriminant analysis

József Kovács, Solt Kovács, Norbert Magyar, Péter Tanos, more

Environmental Modelling and Software > 2014 > 57 > Complete > 52-59

The classification of observations into groups is a general procedure in modern research. However, when searching for homogeneous groups the difficulty of deciding whether further division of a classification is necessary or not to obtain the desired homogeneous groups arises. The presented method, Combined cluster and discriminant analysis (CCDA), aims to facilitate this decision.CCDA consists of...

article

Assessing water-quality data: The relationship between the water quality amelioration of Lake Balaton and the construction of its mitigation wetland

István Gábor Hatvani, Adrienne Clement, József Kovács, Ilona Székely Kovács, more

Journal of Great Lakes Research > 2014 > 40 > 1 > 115-125

Lakes are sensitive to environmental changes and anthropogenic effects; and Lake Balaton, the largest shallow freshwater lake in Central Europe, is no exception. To protect the lake (primarily Keszthely Bay) against elevated nutrient loads, the Kis–Balaton Water Protection System (KBWPS) was constructed as a mitigation wetland at the mouth of the River Zala, the largest tributary of the lake. This...

article

The Water Framework Directive: Can more information be extracted from groundwater data? A case study of Seewinkel, Burgenland, eastern Austria

István Gábor Hatvani, Norbert Magyar, Matthias Zessner, József Kovács, more

Hydrogeology Journal > 2014 > 22 > 4 > 779-794

Water protection is one of the most important goals in environmental protection. The Clean Water Act in the USA and the Water Framework Directive (WFD) in Europe are the legal frameworks to facilitate the achievement of this goal. The question is raised of whether more information can be extracted from WFD-related groundwater data. To answer it, a methodology has been developed that is easy to use...

article

Application of multivariate statistical methods in determining spatial changes in water quality in the Austrian part of Neusiedler See

Norbert Magyar, István Gábor Hatvani, Ilona Kovácsné Székely, Alois Herzig, more

Ecological Engineering > 2013 > 55 > Complete > 82-92

The aim of the present study was to distinguish areas with different chemical properties in Neusiedler See, to determine which background processes are responsible for this pattern, and to discover their spatial distribution. Uni- and multivariate data analysis was applied to the data concerning 13 mainly chemical and some biological parameters for the time period 2000–2009 from 33 sampling sites...

article

Delimiting sub-areas in water bodies using multivariate data analysis on the example of Lake Balaton (W Hungary)

József Kovács, Mária Nagy, Brigitta Czauner, Ilona Székely Kovács, more

Journal of Environmental Management > 2012 > 110 > Complete > 151-158

The main aim of the European Water Framework Directive (WFD, 2000) is to commit European Union Member states to the achievement of good qualitative and quantitative status for all water bodies by 2015. To achieve this, a reference state has to be determined and appropriate monitoring has to be carried out. Based on the fact that the WFD classifies Lake Balaton, the largest shallow freshwater lake...

article

Introducing sampling frequency estimation using variograms in water research with the example of nutrient loads in the Kis-Balaton Water Protection System (W Hungary)

József Kovács, János Korponai, Ilona Székely Kovács, István Gábor Hatvani

Ecological Engineering > 2012 > 42 > Complete > 237-243

In most of the world along with urbanization came the deterioration of surface waters. The case of Hungary's Lake Balaton (the largest shallow freshwater lake in Central Europe) and its catchment area was no exception. In the second part of the twentieth century it became clear that measures had to be taken to prevent further water quality deterioration. In order to do so, the Kis-Balaton Water Protection...

article

Corrigendum to “Morlet wavelet and autocorrelation analysis of long-term data series of the Kis-Balaton water protection system (KBWPS)” [Ecol. Eng. 36 (2010) 1469–1477]

József Kovács, István Gábor Hatvani, János Korponai, Ilona Székely Kovács

Ecological Engineering > 2011 > 37 > 9 > 1438-1440

article

Analysis of long-term water quality changes in the Kis-Balaton Water Protection System with time series-, cluster analysis and Wilks’ lambda distribution

István Gábor Hatvani, József Kovács, Ilona Székely Kovács, Pál Jakusch, more

Ecological Engineering > 2011 > 37 > 4 > 629-635

Lake Balaton is the largest shallow freshwater lake in Central Europe. Its water quality is mainly affected by the supplying rivers and other water sources. The primary source is the Zala River. Its water used to be filtered by the Kis-Balaton Wetland (KBW) before entering Lake Balaton. During the nineteenth century, as a result of artificial water level modifications, the KBW disappeared and the...

article

Morlet wavelet and autocorrelation analysis of long-term data series of the Kis-Balaton water protection system (KBWPS)

József Kovács, István Gábor Hatvani, János Korponai, Ilona Székely Kovács

Ecological Engineering > 2010 > 36 > 10 > 1469-1477

Lake Balaton is the largest shallow freshwater lake in Central Europe. Its water quality is mainly affected by the supplying rivers and other water sources. The primary source is the Zala River. The water of this river used to be filtered by the Kis-Balaton wetland (KBW) before entering Lake Balaton at Keszthely Bay. In the course of the nineteenth century, water level modifications at KBW shrank...

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