Geographia Polonica (2003) vol. 76, iss. 2

Abstract

This article reviews the occurrence and variability of extreme precipitation on the northern slope of the Tatra Mountains (southern Poland), using rainfall amounts of duration from 1 to 30 days. Daily data from 76 years (1927-2002) are used for the Hala Gąsienicowa meteorological station at 1520 m a.s.l. This is the place with the heaviest rainfall in Poland. The highest daily precipitation total (300 mm) was recorded on 30 June 1973 during a northern cyclonic situation. For longer durations extreme values of precipitation were observed during different years. In July 1934 the highest 3-day total reached 422 mm, and during the 11 days between 16 to 26 July 2001 the total amount of rainfall reached 500 mm. In the last 7 years the precipitation totals and the number of extreme events are distinctly greater than in the previous part of the analysed 76 years period, although a strong influence on the results may be the data from the extreme year 2001. However, an earlier period saw extreme precipitation concentrated during the years 1958-1978. A transition to a rather wetter phase of climate has been noted since 1995. However, there is no sign for any of the elements studied of any departure that has exceeded the values typical for fluctuations of climate in the 20th century, and which could therefore be taken as indication a permanent change in the climate.

Keywords: climatic change, extreme precipitation events, Tatra Mountains, Poland

Tadeusz Niedźwiedź, Faculty of Earth Sciences, University of Silesia Będzińska 60,41-200 Sosnowiec, Poland. Institute of Meteorology and Water Management Borowego 14, 30-215 Kraków, Poland.

Abstract

The longest instrumental rainfall series have been investigated for the North Assam subdivision and 4 meteorological stations in Northeast India. Analysis of trends to annual and seasonal rainfall show these to be very stable, with no change in the rainfall over North Assam during the last 150 years. The Fourier analysis of fluctuations in rainfall series shows that the periodic signal of T=3.5 year is the strongest one. Such a signal, with the same phase, has been found for all rainfall stations of the North Assam subdivision and in all investigated seasons.

Keywords: monsoon rainfall, trend, periodicity, northeast India

Paweł Prokop [pawel@zg.pan.krakow.pl], Institute of Geography and Spatial Organization Polish Academy of Sciences, Św. Jana 22, 31-018 Kraków, Poland
Adam Walanus, Institute of Archaeology, University of Rzeszów, Hoffmanowej 8, 35-016 Rzeszów

Abstract

Landslides are common disaster phenomena in many countries causing great economic losses. The Darjiling-Sikkim Himalayas in India is known to be the most severely affected. Even a glance at landslide statistics gives some idea of the enormity of damage done and the ever present threat to lives and property. It has been observed that even 50 mm of rainfall in an hour would cause landslips. Unauthorized structures in the unsafe zones, absence of an adequate drainage system and unplanned growth of settlements have accelerated the process of ecological imbalance. In recognition of the acuteness of problems related to landslides, this paper summarizes our knowledge of slope stability so as to provide information on the origin of slope movements and the methods of their investigation, prevention and control. A series of case studies in the Darjiling-Sikkim Himalayas have been undertaken to provide a better understanding of this acute natural disaster problem.

Keywords: disaster phenomena, inadequate drainage, landslide, slope stability, unsafe zone, India

Subhash Rajan Basu, Department of Geography, University of Calcutta, 35, Ballygunge Circular Road, Kolkata - 700019, INDIA
Sunil Kumar De, Department of Geography, Union Christian Training College, Berhampore -742101, W.B., INDIA

Abstract

The Sudetes are a mid-mountain range located in the temperate climatic zone of Central Europe. Deep valley sides are covered with a thick mantle of peri-glacial regolith. Migrating cyclones cause intensive rainstorms, debris flow and floods. Geomorphological and sedimentological traces of a previous large flood have been found in the upper course of the Bila Opava and Bela valley floors, which drain the northern slope of the Hruby Jesenik massif, 1000-1400 m a. s. 1. Dendrochronological investigation has shown that this large flood took place around the turn of the 20th century. Meteorolo-gical archival records have confirmed that extremely heavy precipitation occurred here on 9 July 1903.The periglacial regolith covering the steep, deforested slopes were the source of the coarse-grained clastic material supplied into the Bila Opava and Bela river beds.

Keywords: climatic and human impact, mountain valleys, alluviation, braided river pattern, Sudetes

Kazimierz Klimek, University of Silesia , Earth Sciences Faculty, ul Będzińska 60, 41-200 Sosnowiec, Poland
Ireneusz Malik, University of Silesia , Earth Sciences Faculty, ul Będzińska 60, 41-200 Sosnowiec, Poland
Piotr Owczarek, University of Silesia , Earth Sciences Faculty, ul Będzińska 60, 41-200 Sosnowiec, Poland.University of Silesia , Earth Sciences Faculty, ul Będzińska 60, 41-200 Sosnowiec, Poland
Edyta Zygmunt, University of Silesia , Earth Sciences Faculty, ul Będzińska 60, 41-200 Sosnowiec, Poland

Abstract

The age of recent glacial, glacifluvial/fluvial forms is determined using lichenometric dating in two Alpine valleys of the Massif des Ecrins in France. A lichen growth-curve is based on data from natural sites, such as boulder-fields, moraine ridges etc. of known age on recently deglaciated terrain. The maximum extent of the glacial system of the Veneon and Etangons valleys during the Little Ice Age was 15 km in length. The maximum lichen diameter of 90-95 mm characterizes the stage of recession correlated with AD. 1650-1660. Analysis of the systems of terraces and paleochannels of the progla-cial rivers supported by lichenometric dating allows three periods of intensified fluvial activity to be distinguished for the Little Ice Age.

Keywords: deglaciation landforms, lichenometry, Little Ice Age, Massif des Ecrins, France

Maria Baumgart-Kotarba, Institute of Geography and Spatial Organization Polish Academy of Sciences, Św. Jana 22, 31-018 Kraków, Poland
Jean-Paul Bravard, Université de Lyon 2, Faculté GHHAT, 5, av. Pierre Mendes, 69676 Bron, France
Michel Chardon, Institut de Géographie Alpine, 14 bis av. Marie-Reynoard, 38100 Grenoble, France
Vincent Jomelli, Institut de Géographie, Université Paris I-Sorbonne, 191, rue Saint-Jacques, 75005 Paris, CNRS Laboratoire de Géographie Physique 1, pl. A.Briand 92195, Meudon Cedex, France
Stanisław Kędzia [kedzia@zg.pan.krakow.pl], Institute of Geography and Spatial Organization Polish Academy of Sciences, Św. Jana 22, 31-018 Kraków, Poland
Adam Kotarba [kotarba@zg.pan.krakow.pl], Institute of Geography and Spatial Organization Polish Academy of Sciences, Św. Jana 22, 31-018 Kraków, Poland
Pierre Pech [pierre.pech@univ-paris1.f], Institut de Géographie, Université Paris I-Sorbonne, 191, rue Saint-Jacques, 75005 Paris, CNRS Laboratoire de Géographie Physique 1, pl. A.Briand 92195, Meudon Cedex, France
Zofia Rączkowska [raczk@zg.pan.krakow.pl], Institute of Geography and Spatial Organization Polish Academy of Sciences, Św. Jana 22, 31-018 Kraków, Poland

Abstract

The author's investigations in the territory of the Myjava Hill Land, Slovakia revealed two periods of gullying in the course of the second half of the last millennium, the first dated to some time between the second half of the 16th century and the 1730s and the second approximately between the 1780s and the middle of the 19th century. Though the extensive forest clearance and expansion of farmland provided conditions favouring gullying, the triggering mechanism of the disastrous gully erosion were extreme rainfall and snowmelt events within the Little Ice Age (LIA). The comparison of gully formation phases identified in the study area with stages of gullying known from some other central-European countries suggests that gullying was not fully simultaneous across the region. The older phase identified in the Myjava Hill Land, does not have an equivalent in Germany, Poland, or Hungary and to a considerable degree in Czechia either.

Keywords: gully evolution, periods of gullying, land use changes, climatic changes, Slovakia

Milos Stankoviansky, Department of Physical Geography and Geoecology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynskä dolina, 842 15 Bratislava 4, Slovak Republic

Abstract

Human activities have affected the paleoenvironmental system in the South Bavarian loess rolling hills and adjacent areas since neolithic times. The Holocene landscape history, influenced by human and/or climatic forces, can only be reconstructed if colluvial deposits, soils and floodplain sediments (flood loam, Auenlehm) of small and large river valleys are investigated in a synoptic way: the onset of the sedimentation of colluvial deposits took place hundreds to thousands years earlier than the formation of the floodplain sediments. The time delay between sedimentation on the hills and in the flood-plain areas depends on the steepness and morphology of the paleorelief. A morphodyna-mic cascade system illustrates the different ages of the sediments. As important geoarchi-ves, colluvial deposits document the beginning of the human-caused landscape changes, but they cannot record climatic signals. On the other hand, floodplain sediments alone cannot be used to represent the age, nature and extent of prehistoric erosion.

Keywords: colluvial deposits, Holocene landscape, human activities, morphody-namic cascade system, paleoenvironmental system, prehistoric soil erosion, Southern Bavaria

Klaus Heine, Institute of Geography, University, D-93040 Regensburg, Germany
Hans-peter Niller, Department of Geography (Physical Geography), Universitätsstr. 31, 93040 Regensburg, Germany

Abstract

Knowledge of rapid changes taking place in natural environments is of fundamental importance for better understanding of man-induced processes, which should be recognized and managed. In Estonia, extreme events have been caused by meteorite explosions, earthquakes, and neotectonic processes, heavy storms, karst phenomena and human impact. Investigation of past processes provides a major key in predicting the chan-ges that could be expected in the same or similar areas in the future. All the above-mentio-ned phenomena have been analysed on a local and regional scale, but they all are part of global-scale processes activated during the last decades.

Keywords: extraterrestrial phenomena, earthquakes, land upheaval, floods, aeolian processes, karst, human impact

Anto Raukas, Institute of Ecology at Tallinn University, Uus-Sadama 5, Tallinn 10120, Estonia

Abstract

The significance of extreme events in landform change is discussed in the context of the late Quaternary. Millennia-scale cycles of climate change are less than the relaxation times of most landform systems and have led to widespread disequilibrium in natural landscapes. Slope failu-res and fluvial systems show parallel evolutionary trends in high and low latitudes, resulting from late Quaternary environmental changes. The transformation of geomorphic systems appears to require millennia of preparation time and research needs to establish the role of individual events within this timescale of enquiry.

Keywords: climate change, extreme events, fluvial systems, slope failures

Michael F. Thomas, School of Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, Scotland, UK

Abstract

This paper discusses the concept of magnitude and frequency introdu-ced by Wolman and Miller in the middle of the 20th century. The concept is outlined and exemplified from recent examples and reference is made to the need for revision in the light of (a) the interaction between extreme events and human activity; (b) developments in hillslope hydrology, and (c) emergence of our understanding of non-linear behaviour.The extremeness of extreme events is identified through work-done plots and thro-ugh conventional statistical probability density functions. It is shown to be controlled (for runoff events) in the short term by vegetation cover, surface crusting and channel network evolution. For the longer term the paper addresses the impact of climatic changes through the vegetation cover by investigating the lagged nature of the response and the amplifica-tion or damping of the response through non-linear behaviour.

Keywords: extreme events, logistic behaviour, non-linearity, magnitude and fre-quency, stability and instability, vegetation

John B. Thornes, Research Chair in Physical Geography School of Social Sciences and Public Policy King's College London London WC2R 2LS, UK

Abstract

The world is approaching limits of growth and consequently facing de-pletion of natural resources and widespread environmental degradation. The sustainabili-ty of many present economic activities is problematic and the interaction between humani-ty and environment more crucial than ever. The critical situation is recognized in scientific and engineering circles and by decision makers at all levels. Creeping hazards and related disasters, such as land degradation and desertification, are on the rise and instantaneous environmental disasters are of growing concern too. Natural hazards of exogenous origin, such as floods and landslides, have natural as well as human causes while those of endoge-nous origin, such as volcanic eruptions and earthquakes, have natural causes only. How-ever, the disasters associated with hazards of any kind are particularly severe in densely po-pulated regions and in areas more vulnerable to extreme events because of environmental and/or economic marginality. Extreme events are most effective as a destructive element where environmental degradation has been provoked by inappropriate land utilization. Climatic changes and lack of awareness and preparedness are aggravating factors. Modern scientific concepts and emerging powerful technologies provide new tools for addressing the problem of balancing human needs and environmental equity.

Keywords: aerospace technology, creeping disasters, disaster mitigation, early warning, extreme events, hazard zoning, natural disasters, susteinability, vulnerability

Herman Th. Verstappenen, International Institute of Geoinformation Science and Earth Observation (ITC), Hengelosestraat 99, POBox 6, 7500AA Enschede, The Netherlands

Abstract

The paper discusses ways in which geomorphology might be used by engineers and planners. They have always appreciated that a project should be based on a clear understanding of the geomorphology of the site of the proposed works. In many countries, following the lead given by Poland, it is now standard practice to take full account of the morphology and processes of the landscape during an investigation. However, many investigation teams tend to restrict the work to ba-sic mapping and identification of features rather than a true understanding of the site in space and time. Not enough attention is paid to the residual effects of earlier landform change, the identification of inherited trends of change or the residual material conditions. Many projects do not have a long eno-ugh time scale to determine the frequency and magnitude of processes and the nature of risk even over the short design life of the project. Such deficiencies in practice are discussed and ways of impro-ving the service are identified. Future work should be based on a full understanding of the conceptual basis for modern geomorphology. In the last thirty years there has been a revolution in the theoretical basis of the subject as well as a remarkable improvement in the technical capability. It is suggested that this should form a new conceptual basis for application to engineering and planning. Now that it is possible to discover fundamental information on how natural systems work it is negligent to carry out development or management of the surface of the Earth without basing the schemes on sound and available knowledge. It is the only home we have.

Keywords: applied geomorphology, engineering geomorphology, event frequency and ma-gnitude, geomorphological concepts, human well-being, inheritance, planning, risk, systems

Denys Brunsden, Department of Geography, King's College, London, WC2R 2LS, UK