Among the sandy eolian relief forms a distinction can be made between depository dunes and erosional dunes. The former are characterized by a positive sand balance, the latter by a negative balance, i. e. sand export is larger than import. The three
types of erosional dunes deflation hole dunes (dunes en creux), parabolic dunes, and sand ridges) are described and a hypothesis advanced on their significance in a paleoclimatic and climatic context.
Aeolian deflation ; Aeolian transport ; Arid area ; Dune ; Earth surface processes ; Model ; Vegetation
A simple model for the dynamics of dunes associated with vegetation is proposed. Using the model, the formation processes of transverse dunes, parabolic dunes and elongated parabolic dunes are simulated according to 2 environmental factors
of the complex interplay between vegetation and dunes.
Linear dunes near the Orange River : origin, mineralogy and climate
Afrique du Sud ; Dune ; Eolien ; Paléogéographie ; Quaternaire ; Sable
Dune ; Eolian features ; Palaeogeography ; Quaternary ; Sand ; South Africa
An examination of the linear sand dunes on either side of the lower Orange River suggests they are of arid Quaternary origin and unrelated to river activity. - (AJC)
The shape and behaviour of the barchan dunes on the Kuiseb River delta, south of the town of Walvis Bay, and the temporal and spatial variability of those characteristics are the focus of this study. - (AJC)
Bagnold's model for the formation of seif dunes from barchans supported by Lancaster (1980), is reviewed. A new model was developed based on field work done in the northern Sinai desert that does not differentiate between the effects of strong
Nearest neighbor methods applied to dune field organization : the Coral Pink Sand Dunes, Utah, USA
Analyse de voisinage ; Dune ; Eolien ; Etats-Unis ; Géomorphologie ; Photographie aérienne ; Système d'information géographique ; Technique de recherche ; Utah
Aeolian features ; Aerial photography ; Dune ; Geographical information system ; Geomorphology ; Research technique ; United States of America ; Utah
Using the Coral Pink Sand Dunes in southern Utah as a model, this study tests nearest neighbor analysis adapted as a method to objectively identify and characterize differences in two dimensional dune patterns within a dune field and to identify
changes in dune patterns over time. Reducing transverse and barchanoid dunes from linear to three-point features in planar space emphasizes the clustering that occurs when dune lengths and wave lengths are more disorganized or random. This clustering may
Après une présentation du pays et des dunes, l'ouvrage étudie la structure de l'accumulation éolienne à l'aide de sections sur trois dimensions dans le sable préalablement mouillé. Le but est d'interpréter les divers types de dunes, linéaires, star
dunes (ghourd), barkhanes, transverse ou reversing dunes, domes, blowout dunes, coppice dunes (nebkas), interdunes| l'A. explique les types complexes par l'action de vent de directions différentes. Belles photos, principalement au sol. (J. Dresch).
Aeolian features ; Aeolian transport ; Arid area ; Barchan ; China ; Dune ; Earth surface processes ; Model ; Shear stress ; Simulation ; Xinjiang
Transverse dunes appear in regions of mainly unidirectional wind and high sand availability. A dune model is extended to two-dimensional calculation of the shear stress. It is applied to simulate dynamics and morphology of three-dimensional
transverse dunes. In the simulations they seem to reach translational invariance and do not stop growing. Hence, simulations of two-dimensional dune fields have been performed. Characteristic laws were found for the time evolution of transverse dunes
. Bagnold's law of the dune velocity is modified and reproduced. The interaction between transverse dunes led to the interesting conclusion that small dunes can travel over bigger ones.
Coastal dune development in cold-climate environments
Arctique ; Dune ; Déflation éolienne ; Littoral ; Neige ; Vent ; Végétation ; Zone froide ; Zone subarctique
Arctic Region ; Coastal environment ; Cold area ; Dune ; Eolian deflation ; Snow ; Subarctic zone ; Vegetation ; Wind
This paper reviews the occurence and morphology of coastal dunes developed in arctic and subarctic environments. The characteristic features of cold-climate coastal aeolian landforms are discussed, and some consideration is given
to the environmental conditions that may explain the different types of dunes found in these environments.
Aeolian features ; Aeolian transport ; Arid area ; Botswana ; Desert ; Dune ; Plant cover ; Wind erosion
The aims of this study are: first, to establish the level of sediment transport acivity on linear dunes in the southwest Kalahari, and secondly, to identify the role of vegetation in the dynamics of the dune system.
Sand columns, sand cones, sand mushrooms and other striking sand forms are frequently observed in the Dutch and German beach and dune sands. The objective of this study is to describe, explain and illustrate the origin of sand columns in bare dune
Relations of sand trapping efficiency and migration speed of transverse dunes to wind velocity
Dune ; Eolien ; Géomorphodynamique ; Modèle ; Transport éolien ; Vitesse du vent
Aeolian features ; Aeolian transport ; Dune ; Earth surface processes ; Model ; Wind speed
A self-consistent model which describes transverse dune migration in equilibrium is introduced. It shows that an equilibrium expression for dune migration speed (Cd) must take into account sand trapping efficiency (Te), and that Te is strongly
Peu de datations existent malgré l'abondante littérature. Les dunes les plus anciennes sont d'avant 5 000 BP. On connaît plus d'épisodes d'édification pour les deux derniers millénaires que pour les derniers siècles : A Magillan, six épisodes ont
Les dunes d'Europe peuvent être classées selon l'origine de leurs dépôts (provenant des rivières, des falaises, du fond de l'océan)| leur composition (calcaire, quartz, mixte)| leurs formes dominantes (parabolique, transgressive, bordière...)| ou
Aeolian features ; Aggregate ; Clay ; Dune ; Indiana ; Lithology ; Pedogenesis ; Stratigraphy ; United States of America ; Weathering
Three parabolic dunes from the Fair Oaks Dune field in northern Indiana were excavated, in order to study the properties and genesis of lamellae. In this paper, the AA. demonstrate petrogenic (depositional) origin of these lamellae.
This paper describes the existence and maintenance (a day at least) of some unusual crescentic dunes on a frozen beach at Schiermonnikoog. These crescentic dunes displayed a markedly aerodynamic shape, and had a plan view similar to that of barchans
To understand, and perhaps predict, something of the movement of these barchan sand dunes, the A. undertook a study of the dunes using aerial photographs. This led to a general study of sand movement in the surrounding region.
Canada ; Cold area ; Dendrology ; Dune ; Earth surface processes ; Eolian features ; Quebec
The objectives of this research are twofold : 1) to study the radial-growth patterns on a number of trees growing in dunes and 2) to develop methods based on tree-ring techniques to calculate the accumulation, erosion, and migration rates of several