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Zmiany, zmienność i ekstremalne sumy parowania terenowego i ewapotranspiracji potencjalnej w Łodzi w drugiej połowie XX wieku

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Jokiel P. , Uniwersytet Łódzki W. N. G.

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2008

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tom 8

PL

Artykuł powstał w wyniku prac badawczych prowadzonych w ramach Projektu Zamawianego MNiI (K091/P04/2004/11).

EN

The work, which is presented below, is an attempt to keep up with changes and changeability of potential evapotranspiration (EVAP) and surface evaporation (PARTER) in perennial and seasonal aspect. Number of 50-years long series (between 1951-2000) of total monthly evaporation, obtained by Konstantinov method and potential evapotranspiration, calculated by Thornthwaite's formula were analyzed. The calculations based on the data from Łódź-Lublinek hydrological observing station. Mean total annual potential evapotranspiration and surface evaporation during particular time were equal to 632.9 mm and 452.5 mm, while variation coefficients were the following: 3.7% and 6.3%. Both characteristics had positive significant trends (Ol: = 0.05). In perennial scale the alternate sequences of relatively low and high total annual surface evaporation were observed. They appeared rhythmically every 8 years. However, such regularity had not been observed for potential evapotranspiration. Total monthly surface evaporation distribution is the most often approximated by Weibull's function. The calculated quantiJes of the probability of exceeding indicated that in July the evaporation of probability exceeding value of l% might be greater than 90 mm, while in November might slightly exceed 15 mm. Total evaporation of probability of exceeding equal to 99% in winter months were higher than 3 mm, while in summer exceeded 50 mm. The results of investigation seemed to prove that in the studied seasonal structure of surface evaporation and potential evapotranspiration the participation of evaporation and evapotranspiration in winter and spring months (in total annual evaporation) systematically increased, while the participation of summer and autumn months decreased. Despite the fact that the difTerent kinds of the observed changes in seasonal structure of evaporation and evapotranspiration in Łódź were ambiguous, they simultaneously indicate that water shortages would be bigger in the region, as a result of increase of so called balance water loss.

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Przepływy ekstremalne wybranych rzek środkowej Polski w latach 1951-2000

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Jokiel P. , Uniwersytet Łódzki W. N. G.

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2008

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tom 8

PL

Artykuł powstał w wyniku prac badawczych prowadzonych w ramach Projektu Zamawianego MNiI (K091/P04/2004/11).

EN

The following study is an attempt to create a multiaspect statistical analysis of 50-years long sequences of monthly extreme llows of three rivers of central Poland: Warta in Sieradz, Bzura in Sochaczew and Pilica in Przedbórz (1951-2000). Those rivers play leading roles in water management of one of the poorest in surface water regions of country - central Poland. The knowledge of their regime and identification of its changes in time especially due to low and high flows is a basis for future planning and efficient water management in regional scale. Within this work functions of monthly extreme flow distributions were identified and distinct probability quantiles were calculated (fab. 1-2; Attachments I-VI). Looking at flow maxima it was noted that for snow-melt freshets months (lI, Ill, IV) the most characteristic were gamma and Weibull's distributions, while for the months of 'summer freshet (VI, VII, VIII) - gamma and log-gamma functions. In case of monthly minima was slightly different. The greatest number of sequences might have been described by Weibull's distribution, significantly smaller number by log-gamma, last two functions appeared very rarely. The biggest annual specific capacity of probability of exceeding l% characterize Pilica river. It was much bigger than analogous runoffs calculated for Warta and Bzura rivers. For Warta and Bzura annual low llows of probability of exceeding 99% were also 8 times smaller than their ecological discharges. In case of Pilica this difference was about 400% smaller. There were investigated the perennial and seasonal dynamics of extreme llows (attachments VII, IX), changeability of monthly llow amplitudes (Fig. 13, 14) as well the trends and their significance (Tab. 4). Long lasting maximum llow series for months of the same names from cold half-year were investigated in 3 rivers and characterized by negative trends (sometimes statistically significant) - Pilica (XI-IV); Bzura (II, III). The lowest flows period systematically moved from early summer (in 1951-1960) towards late summer or even early autumn (in 1991-2000). This trend was very pronounced and unambiguous. Perennial changeability of warm half-year minimum series was usually smaller than of parallel series in cold half-year. All monthly minima of Warta increased, Pilica's - decreased, while the observed tendencies for Bzura were variegated. Most of the obtained trend lines indicate on tendencies of decreasing in the series of monthly amplitudes, although statistically significant trends are characteristically arranged. Statistically significant trends occur during late winter and early spring (I-II), what is more they concern all studied rivers. The analysis indicate on a small decrease in changeability of flows in investigated rivers, which is characterized by slightly systematic increase of monthly minima and amplitude decrease. However, those phenomena are visible best during cold half-years and concern mainly month of freshets (II, III).

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Maksymalny czas trwania głębokich niżówek letnich w środkowej Polsce i jego uwarunkowania

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Edmund T. , Uniwersytet Łódzki W. N. G.

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2008

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tom 8

PL

Artykuł powstał w wyniku prac badawczych prowadzonych w ramach Projektu Zamawianego MNiI (K091/P04/2004/11).

EN

Maximum duration of extreme summer flows in central Poland was estimated on the base of hydrometric data including twenty four hour flow series from the 1966-1983 period, which were published by IMGW. There were 29 water gauges located in Warta, Pilica and Bzura drainage basins (Fig. l) shortlisted for the analysis. Low flow periods were sectioned basing on a border flow SNQ - a principle was that the period with flows below the borderline had lasted at least 5 days, while low flows followed in succession had to be divided by periods of flows higher than SNQ being minimum 3 days long. Maximum summer flows were at that time very differentiated and their length fluctuated from 10 to 282 days (Fig. 2). According to that some kind of spatial order can be outlined here, the longest low flow periods appeared in Great Poland and Warsaw - Berlin Glacial Valley (Fig. 3). Maximum length of low flow was significantly correlated with the parameters, which illustrated flow recession time, mean time of low flow or extreme time constitution in total low flow and extreme low flow time (Fig. 4, 8). The parameters of maximum length probability distribution were estimated as well. On the base of those calculations was estimated the probability of not achieving the maximum, which was empirically confirmed. Values fluctuated from 90-99.2% usually being about 96% (Fig. 6). The greatest probability of lengthening of maximum low flow periods had Great Poland Rivers (Mogilnica, Wrześnica, Lutynia), while the smallest probability was characteristic for rivers, which origins are in uplands (Warta - Poraj, Pilica - Przedbórz).

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Wprowadzenie (tekst wprowadzający do tomu nr 02/1997 Folia Geographica Physica)

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Maksymiuk Z. , Uniwersytet Łódzki W. N. G.

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PL

Tekst wprowadzający do tomu nr 02/1997 Folia Geographica Physica