Quaestiones Geographicae vol. 29 (3), 2010


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Now showing 1 - 5 of 9
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    Holocene inset fills of the Odra river in the Racibórz basin
    (Wydział Nauk Geograficznych i Geologicznych Uniwersytetu im. Adama Mickiewicza, 2010) Wójcicki, Krzysztof J.; Śleszyński, Przemysław; Mazur, Sławomir
    Geomorphic and lithological research conducted in the Odra River valley between Koźle and Krapkowice led to recognition of the postglacial development of the upper Odra River valley floor, for the first time, on the basis of a larger number of absolute datings. The formation of the inset alluvial fills by a meandering river started during the Early Holocene at the latest; however, the absence of a clearly developed system of large Late Vistulian palaeomeanders is notable within the analysed reach of the valley. Mid- and Late Holocene alluvial series were deposited by a river that exhibited a tendency to decrease in channel sizes. Nevertheless, large meanders were formed again in historical times. Oxbow fills in the Odra River valley are dominated by mineralogenic deposits. Their sedimentation can be correlated with the accretion of overbank and colluvial sheets in the valley floor. In the light of radiocarbon chronology, a relationship between Neolithic and subsequent phases of settlement in the catchment and the intensive deposition of these sediments cannot be ruled out.
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    Forest cover dynamics in the city of Poznań from 1830 to 2004.
    (Wydział Nauk Geograficznych i Geologicznych Uniwersytetu im. Adama Mickiewicza, 2010) Macias, Andrzej; Dryjer, Marta
    Forests on the urban areas are of a great importance for the biodiversity of this territory. Moreover, they play numerous functions in the environment and constitute, at present, on important element of the ecological urban system. Nevertheless, the changes of the forest areas in the city of Poznań have never been discussed so far. This article presents the results of research of the changes of forest areas in Poznań within the administrative borders of Poznań in 2004. It was performed for the period 1830–2004 for six selected moments in which topographic maps of this area were prepared i.e. 1830, 1888, 1940, 1960, 1979 and 2004 During this period forest area increased by 2367 ha. The effect of numerous afforestations and deforestations is that forest area which was not subject to these treatments from 1830 to 2004 constitutes only 481 ha (14.6% of forest areas of Poznań). Four periods of dynamics of changes of forest areas were distinguished. During the last one, taking place presently, forest area has decreased slightly. In the case of Poznań, maintaining forests is significant from the point of view of their importance not only for functioning of green wedges but also the whole environment of this city. Therefore, one of the directions of spatial development of the city of Poznań should be maintaining and increasing forest areas as the element of the implementation of sustainable development principles.
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    Response of the Danube River floodplain to flood events during 2002–2007 period
    (Wydział Nauk Geograficznych i Geologicznych Uniwersytetu im. Adama Mickiewicza, 2010) Lehotský, Milan; Novotný, Ján; Szmańda, Jacek B.
    The relationship between floods and their geomorphic effect is discussed in this article. Almost every flood event is registered in overbank alluvia. We investigated sediment structures and textures as a response to three flood events occurred during 2002–2007 period on the Danube River floodplain in Bratislava. The change in sedimentation is the effect of floodwater flow energy changeability in the channel and floodplain. Generally, three main phases of energy flow changes of floods are recognised and thus the complete flood record can be expressed as the set of three layers. We also analysed conditions of the overbank sedimentation based on the shape and size of sedimented particles. Results show a relatively high variability of sedimentation processes during floods. The total amount of new overbank sediment accumulated in the 2002–2007 period, its texture characteristics and spatial distribution do not depend only on flood discharge, but also on the drainage basin sources of floodwater and sediment.
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    Palaeo-valleys in the region of the Słupia River mouth
    (Wydział Nauk Geograficznych i Geologicznych Uniwersytetu im. Adama Mickiewicza, 2010) Florek, Wacław; Rudowski, Stanisław; Szefler, Kazimierz
    Basing on results of detailed hydroacoustic research, the geological structure of the bottom to 20–22 m b.s.l. has been studied. The palaeo-Słupia palaeo-valley, buried by a thin cover of marine sands, has been recognized and determined. Some stages of valley development may be distinguished. The deposits of the oldest valley are C14 dated at ca. 21 ka BP. But in the main stage, the valley was formed by action of the subglacial and thawing glacial waters during and after the so-called Gardno Phase. Most probably this valley was connected with the Pomeranian ice margin valley. The next stages of the valley’s development were related with changes of the palaeo-Słupia under conditions of the Litorina transgression. The youngest palaeo-Słupia valley is, in the authors’ opinion, related with a shallow, long incision, weakly marked in the sea bottom in the central part of the studied area. Field investigations were carried out by the Department of Operational Oceanography of the Maritime Institute in Gdańsk from the r/v Dr Lubecki. A DESO 15 echosounder, Subbottom Profilers model 3010 and the X Star system were used. Eight vibrocores (core length up to 3 m) were taken from the sea bottom and three borings (10–17 m depth) were executed on the shore. Accurate positioning was obtained using the DGPS and HYDRO and Track Point Systems. All data were digitally recorded and processed.
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    Flood management strategies in frequent and small scale events: lessons learned from Amarante (Portugal).
    (Wydział Nauk Geograficznych i Geologicznych Uniwersytetu im. Adama Mickiewicza, 2010) Tedim, Fantina; Carvalho, Salete
    The 2000/2001 winter was exceptionally rainy in Portugal and between November 2000 and March 2001 several floods occurred. In this period some localities registered the highest floods of the last hundred years. One example is the town of Amarante, in the north of Portugal, that has been affected by several flood events during the time frame previously mentioned. There is no reference of these episodes in the international disaster databases (e.g. Em-data, Darmouth Flood Observatory) because it is a very small scale event, and no fatalities were recorded. However, it is a recurrent situation with considerable direct and indirect damages which affects a small part of the cultural heritage centre which is also an important touristic and commercial area. The objective of this paper is to understand the characteristics of flood risk in Amarante which is a product of the hazard and the vulnerability of exposed elements (e.g. people, environment and structures) in order to improve flood disaster management efficiency. The paper is organized into two parts. On the first one we add new data to the previous knowledge through the identification of flood episodes in two time periods, between 1937 and 1955 and from 1985 to 2001. Each event was characterized according to several parameters (e.g. flood peak, water height, flooding area, duration, and flow velocity) and classified into six levels according to flood magnitude (water height), flooded area (extension) and potential impacts (damages). This approach improves hazard knowledge and systematizes emergency response procedures. It can improve the communication, not only between the different civil protection agents, but also between them and the citizens during the emergency. It can also be useful for assurance companies’ policy. The second part is focused on the management of the March 21st 2001 flood which was the most severe in Amarante’s history at least in the last hundred years. Understanding the damages and the impacts of flood on livelihoods, the emergency procedures, as well as the articulation between people and civil protection agents are fundamental to increase the efficiency of flood risk management strategies and the determination of appropriate protection levels.