The dynamics of lowland river sections of Danube and Tisza in the Carpathian basin
The paper presents a detailed statistical analysis of data from 41 hydrometric stations along the Danube (section in the Carpathian Basin) and its longest tributary, the Tisza River. Most records cover 2–3 decades with an automated high temporal sampling frequency (15 min), and a few span 120 years...
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| Language: | English |
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Frontiers Media S.A.
2025-02-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/feart.2025.1391458/full |
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| author | Imre M. Jánosi Imre M. Jánosi István Zsuffa István Zsuffa Tibor Bíró Boglárka O. Lakatos Boglárka O. Lakatos András Szöllősi-Nagy Zsolt Hetesi Zsolt Hetesi |
| author_facet | Imre M. Jánosi Imre M. Jánosi István Zsuffa István Zsuffa Tibor Bíró Boglárka O. Lakatos Boglárka O. Lakatos András Szöllősi-Nagy Zsolt Hetesi Zsolt Hetesi |
| author_sort | Imre M. Jánosi |
| collection | DOAJ |
| description | The paper presents a detailed statistical analysis of data from 41 hydrometric stations along the Danube (section in the Carpathian Basin) and its longest tributary, the Tisza River. Most records cover 2–3 decades with an automated high temporal sampling frequency (15 min), and a few span 120 years with daily or half-daily records. The temporal sampling is not even and exhibits strong irregularities. The paper demonstrates that cubic spline fits and down-sampling (where necessary) produce reliable, evenly sampled time series that smoothly reconstruct water level and river discharge data. Almost all the water level and discharge records indicate a decadal decreasing trend for annual maximum values. The timing (day of the year) for annual maxima and minima is evaluated. While minimum values do not show coherent tendencies, annual maxima exhibit increasing trends for the Tisza but decreasing trends for the Danube (earlier onset). Various possibilities for the explanations of these observations are listed. The empirical histograms for half-daily water level changes can be well-fitted by piecewise-exponential functions containing four or three sections, consistent with the understanding that level changes are deterministic rather than stochastic processes, as is well known in hydrology. Such statistical tests can serve as benchmarks for modeling water levels and discharges. Extracted periods by the Lomb-Scargle algorithm (suitable for unevenly sampled time series) and the long-time means indicate the expected annual seasonality. Resampled time series (1-hour frequency) were evaluated by standard Fourier and Welch procedures, revealing some secondary peaks in the spectra indicating quasi-periodic components in the signals. Further significance tests are in progress, along with attempts at explanations. Secondary peaks may indicate environmental changes, the future investigation of which could reveal important correlations. |
| format | Article |
| id | doaj-art-b737f637c5e84c5e8d816ac39d465cbb |
| institution | Kabale University |
| issn | 2296-6463 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj-art-b737f637c5e84c5e8d816ac39d465cbb2025-02-12T07:26:24ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632025-02-011310.3389/feart.2025.13914581391458The dynamics of lowland river sections of Danube and Tisza in the Carpathian basinImre M. Jánosi0Imre M. Jánosi1István Zsuffa2István Zsuffa3Tibor Bíró4Boglárka O. Lakatos5Boglárka O. Lakatos6András Szöllősi-Nagy7Zsolt Hetesi8Zsolt Hetesi9Max-Planck-Institute for the Physics of Complex Systems, Dresden, GermanyDepartment of Water and Environmental Policy, Faculty of Water Sciences, University of Public Service, Budapest, HungaryDepartment of Water and Environmental Policy, Faculty of Water Sciences, University of Public Service, Budapest, HungaryWater Resources Research Centre (VITUKI) Hungary Ltd., Budapest, HungaryDepartment of Hydraulic Engineering, Faculty of Water Sciences, University of Public Service, Baja, HungaryDepartment of Water and Environmental Policy, Faculty of Water Sciences, University of Public Service, Budapest, HungaryDoctoral School of Military Engineering, University of Public Service, Budapest, HungaryDepartment of Water and Environmental Policy, Faculty of Water Sciences, University of Public Service, Budapest, HungaryDepartment of Water and Environmental Safety, Faculty of Water Sciences, University of Public Service, Baja, HungaryDepartment of Applied Mathematics, Institute of Mathematics and Informatics, University of Pécs, Pécs, HungaryThe paper presents a detailed statistical analysis of data from 41 hydrometric stations along the Danube (section in the Carpathian Basin) and its longest tributary, the Tisza River. Most records cover 2–3 decades with an automated high temporal sampling frequency (15 min), and a few span 120 years with daily or half-daily records. The temporal sampling is not even and exhibits strong irregularities. The paper demonstrates that cubic spline fits and down-sampling (where necessary) produce reliable, evenly sampled time series that smoothly reconstruct water level and river discharge data. Almost all the water level and discharge records indicate a decadal decreasing trend for annual maximum values. The timing (day of the year) for annual maxima and minima is evaluated. While minimum values do not show coherent tendencies, annual maxima exhibit increasing trends for the Tisza but decreasing trends for the Danube (earlier onset). Various possibilities for the explanations of these observations are listed. The empirical histograms for half-daily water level changes can be well-fitted by piecewise-exponential functions containing four or three sections, consistent with the understanding that level changes are deterministic rather than stochastic processes, as is well known in hydrology. Such statistical tests can serve as benchmarks for modeling water levels and discharges. Extracted periods by the Lomb-Scargle algorithm (suitable for unevenly sampled time series) and the long-time means indicate the expected annual seasonality. Resampled time series (1-hour frequency) were evaluated by standard Fourier and Welch procedures, revealing some secondary peaks in the spectra indicating quasi-periodic components in the signals. Further significance tests are in progress, along with attempts at explanations. Secondary peaks may indicate environmental changes, the future investigation of which could reveal important correlations.https://www.frontiersin.org/articles/10.3389/feart.2025.1391458/fullwater levelriver dischargeirregular sampling timesstatistics of annual maxima and minimacubic spline interpolationempirical distributions and frequencies for water level and river discharge changes |
| spellingShingle | Imre M. Jánosi Imre M. Jánosi István Zsuffa István Zsuffa Tibor Bíró Boglárka O. Lakatos Boglárka O. Lakatos András Szöllősi-Nagy Zsolt Hetesi Zsolt Hetesi The dynamics of lowland river sections of Danube and Tisza in the Carpathian basin Frontiers in Earth Science water level river discharge irregular sampling times statistics of annual maxima and minima cubic spline interpolation empirical distributions and frequencies for water level and river discharge changes |
| title | The dynamics of lowland river sections of Danube and Tisza in the Carpathian basin |
| title_full | The dynamics of lowland river sections of Danube and Tisza in the Carpathian basin |
| title_fullStr | The dynamics of lowland river sections of Danube and Tisza in the Carpathian basin |
| title_full_unstemmed | The dynamics of lowland river sections of Danube and Tisza in the Carpathian basin |
| title_short | The dynamics of lowland river sections of Danube and Tisza in the Carpathian basin |
| title_sort | dynamics of lowland river sections of danube and tisza in the carpathian basin |
| topic | water level river discharge irregular sampling times statistics of annual maxima and minima cubic spline interpolation empirical distributions and frequencies for water level and river discharge changes |
| url | https://www.frontiersin.org/articles/10.3389/feart.2025.1391458/full |
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