Mineralogical and gemorphological characterization of sand dunes in the eastern part of United Arab Emirates using orbital remote sensing integrated with field investigations

In this study, Landsat 7 ETM+ data sets were used to study the geomorphology and mineralogy of different dune types in the eastern part of Abu Dhabi in United Arab Emirates. The extraction and mapping of the dominant mineral phase of the investigated sand dunes were carried out using image processing integrated with field techniques. Band ratios 6/4 and 5/7 were very useful for mineralogical distinction of (i) high mafic content areas (ratio 5/7), and (ii) carbonate and quartz content (ratio 6/4). The results of the present study show that these dunes are classified into several main classes based on composition. The first class is low dunes composed of a mixture of quartz and carbonate, the second class is carbonate-rich, the third quartz-rich and the fourth mafic mineral-rich. Morphologically, the dunes in the investigated area belong to two main types. The first is linear and is trending NE-SW. This type shows transitional change in mineralogy from carbonate-rich components to iron oxide-rich components. This mineral gradient was observed on Landsat images as spectral variations and color tones, and was confirmed from ground truth data. The second type is star dunes and appears in images as radially symmetrical to mound shape that characterize multidirectional wind systems. The results of this study show that multispectral data can be used to differentiate between different dune types and their associated mineralogy, and to reveal information on the dynamic processes shaping dunes, such as prevailing wind directions.