Przegląd Geograficzny (2016) vol. 88, iss. 1
Seasonality to river outflow in Central Poland and its variability over a multiannual period revealed by mass diagram curves and half-outflow terms
Przegląd Geograficzny (2016) vol. 88, iss. 1, pp. 53-74 | 
Full text
doi: https://doi.org/10.7163/PrzG.2016.1.3
Abstract
The work described here has concerned the assessment and analysis of summation curves and variability to half-outflow terms (TPOj ), as calculated for 14 river basins in central Poland. Given the regimes of particular rivers, their characteristic flows and geographical determinants of their outflows, the selected group of river basins proves very suitable for an investigation regarding the type and amount of hydrological information provided with analyzed characteristics. Specifically, the research was concerned with series of daily discharges from the second half of the 20th century. Relative mass diagram curves for daily mean outflows were generated for the particular basins, as was a regional summation curve. A relationship between the shapes and numbers of inflection points and river regime was identified, while it proved possible to represent the curve for the outflow in Central Poland using a degree-4 polynomial. This curve has one significant inflection point near the 170th day of the year (20 April), and the second, less visible in the 280th day of the year (6 August). The rivers studied can thus be assumed to have a nival regime, though transforming locally into a notfully-formed nivo-pluvial regime (in the case of upland rivers). In the middle of the hydrological year (near 1st May), about 60% of water resources are discharged from the Central Poland Basin, though there are some significant differences between basins. For the upland basins and the area of the Łódź Elevation region it is less than 60%, while for the Wielkopolska Lowland basins – much more than 60%. The half-outflow terms for particular basins and individual years were calculated using the method suggested in the work of A. Bartnik and P. Jokiel (2005). The TPOj distribution, mean values, multiannual variability and the spatial dimension were all investigated, and extreme values analyzed using quantiles. Both the spatial dimension to the TPOj and its multiannual variability show certain regularities. The multiannual means for the TPOśr in Central Poland are rather differentiated and are of lengths over one month. The earliest term (12th March) was recorded for the River Ołobok and the latest (17th April) for the Pilica. Some kind of TPOśr spatial dimension order is also to be observed, and is attributable to the fact that rivers draining the lowlands (and thus in the western and north-eastern parts of the area) have their TPOśr earlier than those flowing in the uplands of the eastern and south-eastern parts. Overall, the second half of the 20th century can be said to have displayed a seasonality to river outflow characterized by weather-influenced fluctuations, with no more constant multiannual trend identified. In the light of the results of the analyses carried out, the half-outflow term can serve as a simple measure by which climatic or anthropogenic changes in the seasonal structure of outflow can be indicated.
Keywords: odpływ rzeczny, krzywa sumowa, termin połowy odpływu, środkowa Polska
Citation
APA: Jokiel, P. (2016). Sezonowa struktura odpływu rzecznego w środkowej Polsce i jej zmiany w wieloleciu w świetle krzywych sumowych i terminów połowy odpływu. Przegląd Geograficzny, 88(1), 53-74. https://doi.org/10.7163/PrzG.2016.1.3
MLA: Jokiel, Paweł. "Sezonowa struktura odpływu rzecznego w środkowej Polsce i jej zmiany w wieloleciu w świetle krzywych sumowych i terminów połowy odpływu". Przegląd Geograficzny, vol. 88, no. 1, 2016, pp. 53-74. https://doi.org/10.7163/PrzG.2016.1.3
Chicago: Jokiel, Paweł. "Sezonowa struktura odpływu rzecznego w środkowej Polsce i jej zmiany w wieloleciu w świetle krzywych sumowych i terminów połowy odpływu". Przegląd Geograficzny 88, no. 1 (2016): 53-74. https://doi.org/10.7163/PrzG.2016.1.3
Harvard: Jokiel, P. 2016. "Sezonowa struktura odpływu rzecznego w środkowej Polsce i jej zmiany w wieloleciu w świetle krzywych sumowych i terminów połowy odpływu". Przegląd Geograficzny, vol. 88, no. 1, pp. 53-74. https://doi.org/10.7163/PrzG.2016.1.3