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Aeolian Sediments: Dune Dynamics and Deposits |
Department of Geography, University College London, Gower Street, London WC1E 6BT, UK
Dune networks are one of the commonest of dune types, and yet the least understood. A nomenclature is developed for describing the components of these systems. It uses the idea of dune memory: dune systems with little sand have little memory, those with more sand ‘remember’ the effect of the most dominant wind throughout the year; some dunes may have ‘mega-memories’, remembering events from the Pleistocene. The nomenclature defines the components of dune networks according to both relative dominance and whether the components are transverse, seif-like or nodal elements. Using this nomenclature, the dynamics of two dune networks in the Wahiba Sands of Oman are described. In one low-memory dune system, where individual dunes are 1 to 2 m high, a plot of 150 by 50 m was surveyed. In a second, higher memory dune system, where individual dunes are 5 to 6 m high, a 200 by 200 m plot was surveyed and an intensive study of sand movement was conducted. Both areas were surveyed in January and March 1986. A further survey was conducted in mid-July. Dune movement is related to topographic parameters such as altitude, slope angle and slope azimuth, slope curvature and proximity to other slopes. An analysis of sand loss or gain at one site is also presented. The dunes were found to be highly mobile. Some crests moved up to 80 cm in 9 hr. Movement was restricted to the upper flanks of ridges. However, adjustment to new wind conditions is very quick.
