Гидрография РБ / Интегральные работы / Реки / р.Горынь / ffp-1526

Influence of Climatic Changes on Characteristics of the Spring Flood of the Pripyat Basin Rivers Within the Limits of Ukraine

Ievgeniia Vasylenko 1, Vasyl Grebin 2

1 Ukrainian Research Hydro-meteorological institute, Kyiv, Ukraine

2 Taras Shevchenko Kyiv National University, Geographical faculty, Ukraine

Abstract

Research and calculating the parameters of the spring flood are the most important parts of the doctrine about runoff in the scientific and practical relations. Spring flood defines the general features of regime of river's runoff in Ukraine. The volume of the spring flood runoff is the main part of annual runoff, and on small streams under certain conditions it can form full annual runoff [Klybashev A., Y. Horoshkov, 1970]. Features of the fluctuations of maximum runoff of the spring flood in modern climatic conditions and identifying regularities, that create appropriate prerequisites for changes, is necessary to solve many scientific and practical tasks of rational using of the water resources, increasing efficiency of operation of waterworks edifices [Voitsekhovitch V., L. Luzan, 1999].

Keywords: atmospheric circulation, spring flood, the volume of runoff, intrayearly division of runoff

Urgency of the theme study

Global changes of atmospheric circulation, what took place during the last decades on considerable territory of Europe, influenced on the terms of forming of the hydrometeorological phenomena. Elaborations of Ukrainian climatologists indicate increasing activity of the centers action of the atmosphere of the northern hemisphere for last years and them displacement to the east, and also the absence of significant precipitation in winter in northern Ukraine. This factor should be considered in the researching of processes of maximal levels and discharges formation of the spring floods on the rivers of Ukrainian Polesie. Knowledge about the changes of basic characteristics of the spring flood, which occurred under the influence of climate changes, is exceptionally important for the normal functioning of objects of the economical appointment within the limits of this territory and monitoring the polluted regions of northern Ukraine [Voitsekhovitch V., L. Luzan, 1999].

The main material

Were analyzed changes of such characteristics of the spring flood, as the date of its beginning and end, the volume of runoff, maximum specific discharges, runoff of the spring flood as a percentage of annual runoff and duration of the spring flood on rivers of right-bank part of Pripyat basin.

The paper used data of 25 hydrological posts, located in the right-bank (Ukrainian) part of the Pripyat’s basin, with catchment area from 231 (Vyrka - Svaryni) to 13300 km ² (Sluch - Sarny), and where observation for water runoff conducted. The duration of observations for water discharges for these hydrological posts is 35 - 65 years [Vishnevsky V., A. Kosovets, 2003]. The article presents the results of calculations for 10 hydrological posts.

According to results of our previous researches, the commencement of modern changes period of the hydrological regime of the rivers of Ukraine and Pripyat, in particular, can be attributed to 1989. Consequently, research of characteristics of the spring flood of the basin rivers was made by us for two representative periods: 1) from the beginning of observation (the post-war period) to 1988 inclusive; 2) from 1989 to 2007. [Grebin V., 2008].

Was conducted calculation the volume and maximum specific discharges of the spring flood and runoff of the spring flood as a percentage of annual runoff. Were defined the dates the beginning and the end of the spring flood and it duration on the rivers of investigated territory.

Calculation mean values and the difference of maximum specific discharges of runoff, the volume of runoff and runoff of the spring flood as a percentage of annual runoff, the dates of the beginning and the end of the flood and duration of the spring flood (for hydrological posts and for the right-bank part of Pripyat’s basin in general) was conducted for characteristic periods (Table 1). According to results of researches of the spring flood characteristics were built comparative histograms for two selected periods. (Figures 1-4) [Klybashev A., Y. Horoshkov, 1970]. Digital maps of changes of the spring flood characteristics were built (Figures 5-6).

BALWOIS 2010 – Ohrid, Republic of Macedonia – 25, 29 May 2010

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Table 1 Changes of some characteristics of the spring flood for the two characteristic periods on tributaries of the right-bank Pripyat.

	from the beginning of observation to 1988				1989 – 2007 yy.					Difference, %
		inclusive.
Hydrological posts	maximum	the volume	runoff of the	maximum		the volume		runoff of the			runoff of the
			spring flood					spring flood	maximum		spring flood
	specific			specific						the volume
		of runoff,	as a % of			of runoff,		as a % of	specific		as a % of
	discharges,			discharges,						of runoff
		3	annual			3		annual	discharges		annual
	l/s km2	million m		l/s km2		million m
	2		runoff					runoff			runoff
1		3	4	5		6		7	8	9	10
Pripyat - Rechytsa	29,1	101	44	12,3		73,3		33	-58	-27	-11
Vyzhevka - Staraya	61,1	37,2	45	19,5		25,6		37	-68	-31	-8
Vyshevka
	26,5
Turya - Kovel		48,0	44	14,6		38,2		32	-45	-20	-12
Stokhid - Liubeshiv	24,5	120	41	13,2		115		33	-46	-4	-8
Styr - Lutsk	19,6	299	31	10,2		226		23	-48	-24	-8
Horyn - Derazhnya	26,4	428	32	12,1		329		26	-54	-23	-6
Sluch - Sarny	49,9	687	44	28,8		641		34	-42	-7	-10
Lva - Osnytsk	71,4	18,4	40	48,2		15,2		28	-32	-17	-12
Ubort - Perga	41,0	160	41	25,4		137		34	-38	-14	-7
Uzh - Korosten	60,8	60,6	44	28,7		48,9		37	-53	-19	-7
Average	41,4	144	39	22,4		120		29	-46	-16	-9

BALWOIS 2010 – Ohrid, Republic of Macedonia – 25, 29 May 2010

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Figure 2 Change of the runoff volume of the spring flood for the two characteristic periods on tributaries of the right-bank Pripyat.

BALWOIS 2010 – Ohrid, Republic of Macedonia – 25, 29 May 2010

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Figure 3 Change runoff of the spring flood, as a percentage of annual runoff for the two characteristic periods on tributaries of the right-bank Pripyat.

Figure 4 Change the duration of the spring flood for the two characteristic periods on tributaries of the rightbank Pripyat.

BALWOIS 2010 – Ohrid, Republic of Macedonia – 25, 29 May 2010

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Figure 5 Change the dates the beginning of the spring flood for the two characteristic periods on tributaries of the right-bank Pripyat.

Figure 6 Change the dates the end of the spring flood for the two characteristic periods on tributaries of the right-bank Pripyat.

It was found that the greatest value of maximum specific discharges of the spring flood runoff to 1989 and in modern period observed in the basins of such rivers as Tnya, Smilka and Lva (Figure 1). The smallest value of characteristic that above mentioned, traced on the hydrological post Styr - Mlynok in both periods , but this value decreased from 16.3 l/s km2 (to 1989) to 8.8 l/s km2 (modern period). The average magnitude maximum specific discharge of the spring flood runoff decreased almost in two times (41.4 and 22.4 l/s km2, accordingly) in the modern period. Within the magnitudes of the volume of the spring flood runoff traced similar changes as in the values of maximum specific discharges, but not so significant. The largest volume of the spring flood runoff to 1989 and in the modern period observed on such hydrological posts, as Sluch - Sarny (687 and 641 million m3), Styr - Mlynok (461 and 371 million m3), Horyn – Derazhnya (428 and 329 million m3). For hydrological post Vyrka – Svaryni is characteristic the smallest volume of the spring flood runoff for both periods, but its magnitude decreased from 11.2 million m3 (to 1989) to 7.44 million m3 (modern period). The volumes of the spring flood runoff remain stable on the hydrological posts Stokhid -

BALWOIS 2010 – Ohrid, Republic of Macedonia – 25, 29 May 2010

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Malynivka, Radostavka – Triitsya (Figure 2). In the whole basin the volume of the spring flood runoff decreased by 16% after 1989. The magnitude of the spring flood constitutes smaller percentage of the annual runoff (29 %) in the modern period than it was to 1989 year (39%). In the whole basin, this difference is 10%. The largest volume of the spring flood runoff (percentage of annual runoff) on tributaries of the rightbank Pripyat observed on the hydrological post Pripyat – Lyubyaz before and after 1989 and it is 63 and 45% of runoff per year, respectively (Figure 3). The smallest magnitude above specified characteristic is observe on the hydrological post the Ikva - Velyki Mlynivtsi in both periods and it is 20% (to 1989) and 15% (after 1989). It was found that the earliest dates of the spring flood beginning observed on such hydrological posts, as Styr - Schurivtsi, Radostavka – Triitsya and Styr - Lutsk to 1989 and they mark at the March 3. Latest date of the spring flood beginning is March 11. This date observed on hydrological posts Sluch - Sarny, Pripyat – Lyubyaz (Figure 5). The average date of the spring flood beginning for whole basin falls on 10 March in the first period. This date displaced on the March 1, in the second period. Since 1989 the earliest date of the spring flood beginning observed on February 26 on hydrological posts: Radostavka - Triitsya, Horyn - Jampol. The latest date of the spring flood beginning - 14 March.

The average magnitude, the date of the spring flood end for whole basin observes on May 22, in the first period. The above mentioned date displaced on May 16 since 1989. Before 1989 the earliest date of the spring flood end – May 10 (Ikva - Velyki Mlynivtsi), and the latest date - 10 May (Styr - Mlynok). In the second period these dates displaced for April 6 (Vyrka - Svaryni) and 6 May (Pripyat - Lyubyaz), respectively (Figure 6).

Duration of the spring flood in the whole basin is almost not changed since 1989. In the first period it is 47 days, and in the second - 48. Although, the duration of the spring flood increased after the 1989 for most of hydrological posts (Figure 4). The greatest duration before and after 1989 observed on the hydrological posts such as, the Pripyat – Lyubyaz and Styr - Mlynok, and it consists from 69, 65 and 66 days, 65 days, respectively. The smallest duration of the spring flood is 38 days (Tnya - Bronnyky, Lva - Osnytsk, Noryn - Slavenschyna) in the first period and in the second - 39 (Radostavka - Triitsya, Vyrka - Svaryni, Lva - Osnytsk).

Conclusions

After analysing the following characteristics: the maximum specific discharges, the volume of the spring flood runoff and runoff of the spring flood as a percentage of annual runoff, as well as the dates of the beginning and the end of the spring flood and duration of the spring flood on the rivers of the Ukrainian part of Pripyat's basin, their changes were found after 1989. The significant reduction of magnitudes of main characteristics of the spring flood runoff was found in the modern period, for some hydrological posts even in two times. Dates of the beginning and the end of the spring flood have displaced to earlier terms in the modern period. As for the duration of the spring flood, (the average on a basin) this magnitude has increased since 1989.

This kind of changes of basic characteristics of the spring flood of the Pripyat’s basin rivers can be attributed to intensive growth temperatures of air in winter - spring period, diminishing the depth of soil freezing and value of water equivalent of snow during the last decades of XX century and at the beginning of XXI century.

References

Vishnevsky V., A. Kosovets, 2003: The hydrological characteristics of rivers in Ukraine, Kyiv, Ukraine. Voitsekhovitch V., L. Luzan, 1999: Modern changes in the maximum river runoff on the Ukrainian Polesie rivers. Proceedings UkrRHMI Vol. 247, Kyiv, Ukraine.

Grebin V., 2008: Assessment of modern changes in runoff of the Dnieper River basin (in Ukraine). Meteorology, climatology and hydrology Vol. 50, Part II. Kyiv, Ukraine.

Klybashev A., Y. Horoshkov, 1970: Hydrological calculations, Leningrad, Russia.

BALWOIS 2010 – Ohrid, Republic of Macedonia – 25, 29 May 2010

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