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Accueil du site → Doctorat → Royaume-Uni → 1996 → Spatial and temporal variability of vegetation cover and zones of potential aeolian activity in the southwest Kalahari Desert, determined using satellite data

University of Sheffield (1996)

Spatial and temporal variability of vegetation cover and zones of potential aeolian activity in the southwest Kalahari Desert, determined using satellite data

Leason, Helen C.

Titre : Spatial and temporal variability of vegetation cover and zones of potential aeolian activity in the southwest Kalahari Desert, determined using satellite data.

Auteur : Leason, Helen C.

Université de soutenance : University of Sheffield

Grade : Doctor of Philosophy (Ph.D.) : 1996

Résumé
The southwest Kalahari Desert is a partially vegetated linear dunefield which is subject to episodic aeolian activity. The episodic nature of activity results from spatial and temporal variability of factors such as windiness, vegetation cover and topography.Previously data on vegetation dynamics, partially in terms of its spatial and long term temporal variability has been lacking for this part of the Kalahari. Often rainfall and evaporation have been used as surrogates for vegetation cover in the use of indexes to predict potential aeolian activity. However this takes no account of spatial variability of vegetation cover due to grazing and burning.The amount and variability of dry season (partially senesced) vegetation cover is modelled using Thematic Mapper satellite data which provides a continuous and synoptic view of the vegetation cover of the whole dunefield as well as providing retrospective information during the mid-1980s drought. In order to model total vegetation cover including green and senesced vegetation and ground litter, an index based on the TM red band is used. Estimates of vegetation cover are found to have a relatively large error associated with them but it is possible to define both variability of vegetation cover and areas where vegetation cover is lowest ( 0-20% vegetation cover) and which are therefore susceptible to aeolian activity.Variability of vegetation cover in the Kalahari Gemsbok National Park is compared with that on adjacent pastoral land. Maps indicating the potential for aeolian activity with reference to the amount of vegetation cover are produced. The maps related to other variables which affect aeolian activity in order to predict potential aeolian activity over the dunefield.

Mots clés : Topography ; GIS Geography Geomagnetism Cartography Geodesy Geography Geomagnetism

Annonce : EThOS (UK)

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Page publiée le 29 mai 2009, mise à jour le 22 octobre 2018