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Accueil du site → Doctorat → Royaume-Uni → 1995 → An analysis of the morphological variation of linear sand dunes and of their relationship with environmental parameters in the southwest Kalahari

University of Sheffield (1995)

An analysis of the morphological variation of linear sand dunes and of their relationship with environmental parameters in the southwest Kalahari

Bullard, J.E

Titre : An analysis of the morphological variation of linear sand dunes and of their relationship with environmental parameters in the southwest Kalahari

Auteur : Bullard, J.E

Université de soutenance : University of Sheffield

Grade : Doctor of Philosophy (PhD) 1995

Résumé
Linear dunes are the most common desert dune form usually occurring in extensive dunefields rather than as isolated individuals, for example in southern Africa, the Sahel and Australia. Dunes described as linear do, however, often display a remarkable degree of morphological variation ranging in form from straight parallel-crested dunes to complex network dune forms in which the linear trend is barely discernible. The southwest Kalahari is one such linear dunefield which displays marked internal morphological variability. The intra-dunefield morphological variability in the southwest Kalahari is examined here through the development of a five-class scheme designed to be applied to dune patterns in the region. The application of the classification scheme throughout the dunefield enables the identification of trends in planimetric patterns. Two dominant trends of increasing dune pattern complexity are identified, these are a northwest to southeast trend and a perpendicular southwest to northeast trend.The morphological variability exhibited by the dunes may be attributed to the role of environmental parameters during dune formation and to the history of dunefield activity. The possible roles of wind regime, vegetation, sand supply and topography in determining linear dune morphology are considered. The southeast Kalahari is frequently described as a palaeo-dunefield. This status has been ascribed on the basis of several criteria including the presence of vegetation, a low incidence of sand-transporting winds and non-synchroneity between the present day landforms and climate. The significance and meaning of the term activity in the southwest Kalahari is examined at length with relation to these and other climatic parameters and the implications for the dune pattern evolution. It is concluded that rather than being a palaeo feature, the southwest Kalahari is in fact an episodically-active dunefield

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