W niniejszym artykule analizowany jest wpływ doboru wartości natężeń deszczów miarodajnych na bezpieczeństwo obliczania niezbędnej objętości tzw. małych zbiorników retencyjnych. Przeprowadzone analizy dowiodły, że przyjęcie konkretnego modelu natężeń deszczów miarodajnych ma decydujący wpływ na dobór niezbędnej kubatury zbiornika. Dokonano porównania objętości i czasów opróżniania małego zbiornika o zadanych parametrach doboru wg trzech modeli opadów dla Polski: Błaszczyka, Bogdanowicz-Stachý oraz Suligowskiego. Opisano zróżnicowanie przestrzenne analizowanych wartości wynikowych. Wykazano, ze różnice pomiędzy oszacowanymi objętościami zbiorników, wyznaczonymi na podstawie analizowanych modeli, mogą sięgać nawet około 100%. Wskazuje to na pilną potrzebę opracowania aktualnego i wiarygodnego źródła danych o wartościach natężeń deszczów miarodajnych dla projektowania systemów odwodnień w Polsce. Rozwiązania, analogicznego dla stosowanego w Niemczech – atlasu opadowego KOSTRA. W Polsce odpowiednikiem KOSTRA staje się realizowany aktualnie projekt Polskiego Atlasu Natężeń Deszczów (PANDa).
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In this paper impact of rainfall Intensity-Duration-Frequency (IDF) model assumption on safety of small stormwater detention reservoirs dimensioning in Poland is discussed. The proper assumption of design rainfall intensities models is a key-important issue for detention reservoir volume design. The comparison for volume and emptying time of defined detention tank, calculated using three design IDF models: Błaszczyk, Bogdanowicz – Stachý and Suligowski, is conducted. The spatial distribution of obtained volumes and emptying times values is analysed. The differences between design volumes estimated by means of different IDF models are found to have the possible magnitude reaching up to about 100 per cent. All above shows the urgent need for development of actual and reliable source of IDF values for design of stormwater systems in Poland. It should be solution similar to precipitation atlas KOSTRA used in Germany. Actually being developed Polish Atlas of Rainfall Intensities PANDa is becoming equivalent of KOSTRA in Poland.
The Jabłonna Reef, one of the reefs formed in Wuchiapingian time in the western part of the Wolsztyn palaeo-High (SW Poland), is characterized by quite irregular outlines and consists of three separate reef bodies (ca. 0.5–1.5 km2 each; the thickness of the reef complex is usually >60 m). It is penetrated by four boreholes, which show two distinct phases of bryozoan reef development during deposition of the the Zechstein Limestone. The first one occurred early in the depositional history and botryoidal aragonitic cementation played a very important role in reef formation. This phase of bryozoan reef development terminated suddenly; one possible reason was that a relative change of sea level – first a fall and then a rise – disturbed the upwelling circulation. Consequently, bioclastic deposition predominated for a relatively long time until the second phase of bryozoan reef development occurred, but the latter was not accompanied by dubious early cementation. During this second phase, reticular fenestellid bryozoans were predominant. Subsequently, microbial reefs developed and abound in the upper part of the Zechstein Limestone sections. The general shallowing-upward nature of deposition in the Jab³onna Reef area resulted in reef-flat conditions with ubiquitous, microbial deposits, in the central part of the Jab³onna Reef. Then, the reef-flat started to prograde and eventually the entire Jab³onna Reef area became the site of very shallow, subaqueous deposition. Five biofacies are distinguished in the Jab³onna Reef sections: the Acanthocladia biofacies at the base, then mollusc-crinoid, brachiopod-bryozoan, Rectifenestella and at the top, stromatolite biofacies. They represent a shallowing-upward cycle, possibly with some important fluctuation recorded as the distinctive lithofacies boundary, corresponding to the Acanthocladia/mollusc-crinoid biofacies boundary. The 13C curves of the Jab³onna 2 and Jab³onna 4 boreholes permit correlation of the trends in the middle parts of both sections and confirm the strong diachroneity of the biofacies boundaries, with the exception of the roughly isochronous Acanthocladia/ mollusc-crinoid biofacies boundary. The presence of echinoderms and strophomenid brachiopods indicates that until deposition of the lower part of the Rectifenestella biofacies, conditions were clearly stenohaline. The subsequent elimination of stenohaline organisms and progressively poorer taxonomic differentiation of the faunal assemblage are characteristic for a slight, gradual rise in salinity. The taxonomic composition of organisms forming the Jab³onna Reef shows a similarity to reefs described from England and Germany, as well as the marginal carbonate platform of SW Poland. Filled fissures were recorded in the lower part of the Jabłonna Reef. The aragonite cementation recorded in some fissure fillings implies that they originated in rocks exposed on the sea floor and are neptunian dykes.
Results of an analysis of new 3D seismic data, obtained from the part of the Wolsztyn High in the Pogorzela High area (SW Poland), allow to test the existing knowledge regarding the geologic framework of the Zechstein rocks in this area. A characteristic arrangement of seismic reflectors within pinched-out Zechstein deposits on slopes of the high shows that they are overlapped in relation to the distinct surface of angular unconformity related to the base of the Zechstein-the Z1'seismic boundary. 3D seismic data seems to show that PZ1 strata are absent in the close vicinity of the Pogorzela High with the lower part of the PZ2 cyclothem also absent across the crest. This suggests that the interpretation of the stratigraphy of Zechstein deposits in the Pogorzela-1 and Pogorzela-2 wells (located on the crest of the high) is, in the light of 3D seismic data, questionable. Probably, the initial stages of the Zechstein transgression did not reach the most elevated part of the high, so that the Carboniferous basement is directly overlain by rocks of the Main Dolomite (Ca2), not by the Zechstein Limestone (Ca1) as was previously thought. The lack of Ca1 strata across the crest of the Pogorzela High opens new exploration perspectives in this interval and explains the apparent negative results of boreholes drilled in 1970s. Presumably it also explains differences in formation of these rocks in comparison with the central and western part of the Wolsztyn High (the Kościan-Nowy Tomyśl area).
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