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Assessing the impact of climate change on discharge in the Horyn River basin by analyzing precipitation and temperature data

Lobodzinskyi Oleksandr, Vasylenko Yevheniia, Koshkina Olha, Nabyvanets Yurii

Meteorology Hydrology and Water Management. Research and Operational Applications

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2023

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Vol. 11, Iss. 1

93--106

EN

It is important to investigate the hydrological consequences of current climate change. Hydrological responses to climate warming and wetter conditions include changes in discharge (frequency, amplitude, and volume). This paper describes current climate change and its impact on hydrological flow within the Horyn River basin. Daily air temperature and precipitation data obtained from the 17 meteorological stations located in and nearby the Horyn River basin, in combination with hydrological data (such as daily water discharges obtained from 9 water gauges), were used for the analysis of climate variability and its hydrological consequences. Analyses of meteorological variables and water discharges are crucial for the assessment of long-term changes in the river regime. Thiessen polygons were used to determine the area of influence of assigned specific meteorological stations, which affect the river’s catchments within the Horyn River basin. As a result of the trend analysis, it was observed that discharge within the Horyn River basin decreased over time. These results were congruent with the trends of precipitation data and air temperature data of the stations determined by the Thiessen polygons and basin boundaries. To understand current changes in the daily flow in the basin, changes in air temperature and precipitation for the period 1991-2020 were compared with the period of the climatic norm (1961-1990). A similar analysis was done for daily water discharges. Increasing air temperature and decreasing precipitation in the current period led to a significant decrease in discharges in the Horyn River basin, especially during the spring flood period.

2

Application of Thiessen polygons in control volume model of solidification

Mochnacki B., Ciesielski M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 23, nr 2

75-78

EN

Purpose: In the paper the possibilities of Thiessen polygons (THP) application in numerical modelling of solidification process are presented. The control volumes of THP shapes (2D task is considered) are very convenient both for the construction of effective and exact control volume method algorithm and allow in simple way to approximate the real shape of domain considered. Additionally the positions of CV central points can be selected in a optional way. Design/methodology/approach: The control volume method algorithm bases of the energy balances for successive CV. They are constructed under the assumption that the boundary-initial problem considered is non-linear and the evolution of latent heat is taken into account using the one domain approach (the substitute thermal capacity of material is introduced). Findings: The method here presented allows to determine the transient temperature field in a non-homogeneous system casting-mould and to observe the course of casting solidification. The local cooling (heating) curves can be found at the optional set of points from the casting-mould system. The heat transfer model can be additionally supplemented by the model concerning the macrosegregation process. Practical implications: The control volume method in a version presented in this paper can be an effective numerical tool both on the stage of foundry technologies design and also in the case of existing technologies analysis. Originality/value: The coupling of the concept of Thiessen polygons application for 2D domain dicretization with the control volume method approach seems to be the original achievement of the authors of this paper.

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Application of the Thiessen polygons in numerical modelling of heat transfer

Mochnacki B.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2004

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z. 78

241-244

EN

In the paper the control volume method is applied for numerical modelling of solidification and cooling processes proceeding in the 2D domain. In particular the control volumes corresponding to the Thiessen polygons (TP) are introduced [1, 2, 3]. The geometrical properties of TP assure the possibility of good approximation of the energy balances being the base for CVM equations construction. In the final part of the paper the example of computations is shown.

4

Komputerowa generacja struktury pierwotnej odlewu

Ciesielski M., Mochnacki B.

Archiwum Odlewnictwa

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2002

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R. 2, nr 4

99--104

PL

W pracy przedstawiono sposób generowania siatki objętości kontrolnych wykorzystywanych do modelowania procesu krzepnięcia w skali mikro/makro z wykorzystaniem teorii Johnsona-Mehla-Avrami-Kołmogorowa (zadanie 2D). Objętości kontrolne tworzone są w postaci wieloboków Thiessena, co pozwala na etapie obliczeń numerycznych w prosty sposób wykorzystać metodę bilansów elementarnych. Rozkład węzłów (środków ziaren) w rozpatrywanym podobszarze jest losowy z narzuconymi z góry pewnymi warunkami ich rozmieszczenia. W końcowej części pracy pokazano przykłady wygenerowanych siatek.

EN

The method of the mesh generation which can be used for numerical modelling of the solidification in micro/macro scale (2D task) on the basis of Johnson-Mehl-Avrami-Kolmogorov theory is presented. The control volumes correspond to the Thiessen polygons, it allows on the stage of numerical modelling to apply, in the simple way, the control volume method. The distribution of the control volumes central points (the centers of grains) is random one, but the certain limitations and postulates can be taken into account. In the final part of the paper the examples of the structures obtained are shown.