Geographia Polonica (2009) vol. 82, iss. 1

Abstract

The analysis concerned the variability of daily precipitation totals observed during thesecond half of the 20th century at fi ve stations in Poland. The elements examined were number of dayswith precipitation exceeding given thresholds, lengths of wet and dry spells and precipitation amountsin a single spell. There is an upward trend for the number of spells and days with precipitation, anda downward trend for mean precipitation during a given spell. Changes in peak precipitation are notuniform, there being negative trends at some stations and positive ones at others. However the lack ofa trend for precipitation totals combines with the climatic warming now to be observed to imply riskof a water defi cit.

Keywords: wet spell, dry spell, precipitation extremes, linear trend, Poland

Joanna Wibig, Department of Meteorology and Climatology, Faculty of Biology and Earth Science, University of Lodz Lipowa 81, 90-568 Łódź, Poland

Abstract

The daily minimum and maximum temperatures at seven Polish stations were used in ananalysis of the occurrence of heatwaves in the years 1951-2006. Heatwaves were defi ned as days withtemperatures exceeding selected thresholds (tmax ≥25°C, tmax ≥30°C, tmin ≥18°C). The mean length ofa wave of very warm days lasts from 2-4 days, the longest no fewer than 23 days. Waves comprising hotdays and nights are shorter. The frequencies of very warm and hot days and hot nights increased in theanalyzed period, especially its second half (1979-2006). The occurrence of heatwaves characteristicallylinks up with high-pressure systems over Central Europe, along with associated blocking episodes.

Keywords: extreme temperatures, Sen’s slope, Lund classifi cation, composite method, Poland

Joanna Wibig, Department of Meteorology and Climatology, Faculty of Biology and Earth Science, University of Lodz Lipowa 81, 90-568 Łódź, Poland
Agnieszka Podstawczyńska, Department of Meteorology and Climatology, University of Łódź Narutowicza 88, 90-139 Łódź, Poland
Marcin Rzepa, Department of Meteorology and Climatology, University of Łódź Narutowicza 88, 90-139 Łódź, Poland
Piotr Piotrowski, Department of Meteorology and Climatology, University of Łódź Narutowicza 88, 90-139 Łódź, Poland

Abstract

The daily minimum and maximum temperatures at nine stations in Poland were used in ananalysis of the occurrence of coldwaves, where these are defi ned as days with temperatures exceedingselected thresholds (tmin ≤ -20°C, tmin ≤ -15°C and tmax ≤ -10°C) in the period 1951-2006. Cold nightsoccurred more often than very cold days and nights but the mean lengths of waves of cold nights weresimilar – lasting a little more than 2 days on average. The frequencies of extremely cold days revealeda slight, but statistically non-signifi cant downward trend. The occurrence of coldwaves was associatedwith high-pressure systems over Central Europe and with blocking episodes, but it was always linkedwith a thick layer of cold air.

Keywords: extremely low temperature, trend, Sen’s slope, least squares method, Poland

Joanna Wibig, Department of Meteorology and Climatology, Faculty of Biology and Earth Science, University of Lodz Lipowa 81, 90-568 Łódź, Poland
Agnieszka Podstawczyńska, Department of Meteorology and Climatology, University of Łódź Narutowicza 88, 90-139 Łódź, Poland
Marcin Rzepa, Department of Meteorology and Climatology, University of Łódź Narutowicza 88, 90-139 Łódź, Poland
Piotr Piotrowski, Department of Meteorology and Climatology, University of Łódź Narutowicza 88, 90-139 Łódź, Poland

Abstract

An important source of risk in agricultural production is the variability to crop yields refl ectingirregularly changing weather. This variability may be described as a stochastic process that has a functionof density. Analyses of historical data on crop yields reveal that the function of density changedfrom right-skewed to left-skewed, along with increasing mean yields. All examined yields of cropscultivated recently in Poland demonstrate the left skew, which does not diminish with the aggregationof acreage. A fairly good approximation of the probability distribution for actual yields may be obtainedusing the log-normal distribution with an inverted abscissa.

Keywords: crop yields, density function, log-normal distribution, area aggregation, scaling of variance

Tadeusz Gorski, Department of Agrometeorology and Applied Informatics, Institute of Soil Science and Plant Cultivation – State Research Institute Czartoryskich 8, 24-100 Puławy, Poland

Abstract

This article looks at certain socioeconomic consequences of extreme hydrometeorologicalphenomena in the Polish Lowland, e.g. fl oods, droughts, hurricanes, heat and cold waves that haveall become more intense in Poland over recent years. The particular focus is on the impact of extremehigh temperature and severe cold events on socio-medical parameters such as mortality. The analysis isespecially concerned with increased daily numbers of deaths in 3 large urban centers located in northeastPoland.

Keywords: extreme hydrometeorological phenomena, heat waves, cold waves, human mortality, Polish Lowland

Magdalena Kuchcik [mkuchcik@twarda.pan.pl], Institute of Geography and Spatial Organization Polish Academy of Sciences, Twarda 51/55, 00‑818 Warszawa, Poland
Marek Degórski [m.degor@twarda.pan.pl], Institute of Geography and Spatial Organization Polish Academy of Sciences, Twarda 51/55, 00‑818 Warszawa, Poland

Abstract

When estimating the reach of the fl ood zones, a mathematical model that describesthe fl ood wave propagation, as well as the digital elevation models can be used. In this study,a two step approach has been applied. In the fi rst step, in order to fi nd the most relevantfl ooding areas, a one dimensional hydraulic model HEC-RAS has been used, which assumessteady state fl ow conditions and a discharge of Qp1% = 7210 m3/s and Q p 0.1%= 9960 m3/s.The segment of the Vistula Valley analysed is 47.05 km long. In the second step, a smallerarea has been analysed using the 2D hydraulic model of shallow water fl ow which is based onthe Roe scheme of fi nite volume method.

Keywords: Warsaw, Vistula River, fl ood zone maps, inundation modelling

Artur Magnuszewski, University of Warsaw, Hydrology Department, Krakowskie Przedmieście 30, 00-927 Warszawa, Poland
Małgorzata Gutry-Korycka, Faculty of Geography and Regional Studies, University of Warsaw Krakowskie Przedmieście 30, 00-927 Warszawa, Poland
Michał Szydłowski, Gdańsk University of Technology, Faculty of Civil and Environmental Engineering, Narutowicza 11/12, 80-952 Gdańsk, Poland

Abstract

This study presents changes in water conditions in the Lublin agglomeration, especiallyas regards discharges from the Bystrzyca and other rivers. Areas covered with impermeable materials,such as asphalt and concrete, have caused changes in directions of surface runoff and an intensifi cationof this process, with effects on the discharges of rivers. The regime of fl ooding is the consequence ofnatural and anthropogenic conditions. Spring and summer fl oods in Lublin and at water gauges belowthe city are mainly caused by surface runoff from the urban area. During periods of snowmelt periods ortorrential rain, water fl ows rapidly through the system of stormwater drainage, and then into the rivers.

Keywords: anthropopressure, river discharges, fl oods

Joanna Sposob, Department of Hydrography Institute of the Earth Sciences Maria Curie-Skłodowska University Akademicka 19, 20 – 033 Lublin, Poland

Abstract

The paper examines annual extreme sea levels along the Polish Baltic coast. The analysisis based on water level data sets collected at gauging stations in Świnoujście, Kołobrzeg, Ustka, andGdańsk in the years 1946-2001. The article also draws upon historical data. The results of the studyshow that differences between the maximum and minimum levels have increased, particularly duringthe last 50 years. Sea level amplitudes tend to be wider in the western part of the Baltic coast than in theeastern part. Extreme sea levels occur in the autumn and winter months.

Keywords: southern Baltic, extreme sea levels, storm surges, storm falls

Bernard Wiśniewski, Maritime University of Szczecin, Wały Chrobrego 1, 70-500 Szczecin, Poland
Tomasz Wolski, Institute of Marine Sciences, University of Szczecin, Wąska 13, 71-415 Szczecin, Poland
Halina Kowalewska-Kalkowska, Institute of Marine Sciences, University of Szczecin, Wąska 13, 71-415 Szczecin, Poland
Jerzy Cyberski, Institute of Oceanography, University of Gdańsk, Marszałka J. Piłsudskiego 46, 81-378 Gdynia, Poland