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Morphodynamics of small high-mountain wadis in arid zones (on the examples of the tributaries of the upper Dades River, High Atlas Mountains, Morocco)

Dłużewski M., Krzemień K., Rojan E., Biejat K., Kokosiński Ł.

Landform Analysis

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2013

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Vol. 22

9--19

EN

The paper reports on a study of the impact of morphology and lithology of small catchments on episodic river channel development in the southern High Atlas Mountains in Morocco. A detailed analysis focused on three catchments of small wadis featuring different relief and lithology along the upper, middle and lower course of the Dades River. The fieldwork combined with an analysis of topographic and geological maps and of satellite images concluded that the development of the river valley and channel structures was related to the main stages in the development of the landform in this part of the High Atlas. The channel dynamics were found to be typical of arid mountains, which was particularly apparent within a denudational-and-fluvial zone that reached up to 3,000 m a.s.l. The dominant morphodynamic system of this zone was pluvio-gravitational where episodic heavy rainfall events triggered fast displacement of stone mantle covers down the slopes and into the river channels. An analysis of the deposition zones in the lower channel reaches and on alluvial fans at the confluence of the side valleys and the main valley leads to the conclusion that the main factor, which determines the channel morphology is the impact of debris flows and heavily loaded streams and rivers. The deposited material is then transported outside the mountain zone and deposited within broad river channels. The development of the river channels in the three catchments depends on their order, morphometric property, slope lithology and the amount of material received from the slopes.

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Natural environment predispositions of North - western Pamirs towards development of contemporary morphogenetic processes

Rojan E.

Landform Analysis

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2009

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Vol. 11

60-70

EN

Natural environment of high mountains is undergoing rapid changes. One of its elements is the relief. What needs to be particularly emphasized here is its contemporary morphogenesis. The aim of the study is an attempt to define the predisposition of natural environment of the chosen region (NW) of the Pamirs towards the development of contemporary morphogenetic processes. In order to carry it out, quality classes method was implemented. Quality classes method was carried out on two kinds of basic fields of assessment: geometric and natural (geomorphologic). It was preceded by a selection of 14 characteristics of the study area, elements or components of the natural environment, which were analysed from the perspective of their influence on initiating, change of intensity or vanishing of the contemporary land formation processes. Maps of predisposition of natural environment of north-western part of the Pamirs towards the development of modern morphogenetic processes for the two kinds of fields constitute the final result of the study. Gained results enable to state that the significant part of the study area is characterized by big predispositions towards the development of contemporary morphogenetic processes. However, on the basis of research on location it was find out that in a few places there is a more intensive forming of the surface than it results from the gained results. Areas of average and small predispositions almost precisely coincide with the range of big Pamirs glaciers. Moreover, it can be said that an extremely important issue for the high mountain region characterized by a big spatial changeability of all analyzed elements of natural environment is the size of the basic field of assessment.

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Morphological changes within road incision forms in the blowdown area in the Slovak Tatra Mountains after termination of intensive forest works

Rojan E.

Landform Analysis

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2009

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Vol. 10

117-123

EN

Natural environment of the Slovak High Tatra Mountains, including landforms, underwent a rapid change. On November 19, 2004, following a disastrous bora, a blowdown area was formed covering 12,600 hectares, and bearing nearly 3 million cubic metres of fallen wood. Necessary forest clearing works related to damage mitigation began in spring 2005. These consisted in cutting and taking down the wood using heavy machinery and vehicles. Intensive after-disaster works led, however, to changes in the depth and density of cart roads. The aim of this paper is to estimate the direction and rate of changes within road dissections after intensive forest works. To achieve this task, the results of measurements of the depth of road incision along selected profiles situated at places differing by inclination and the type of exploitation were used. The collected data point to dominant, although minor role of accumulation processes over erosive ones, the latter being important during the period of relatively not intensive road exploitation. The most important factor contributing to such a denudation balance of gently inclined (up to 20 centigrade) roads appears to be human impact, dominating over properties of natural environment. Hence, termination of intensive road exploitation and introduction of anti-erosive measures, such as steps on steeper (more than 15 centigrade) road segments, are most effective when preventing erosion processes within the latter in the blowdown area in the Slovak High Tatra Mountains.

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Współczesna morfogeneza północno - zachodniej części Pamiru : próba ujęcia bilansowego

Rojan E.

Landform Analysis

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2008

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Vol. 9

123--128