Barchan dunes are found where sand availability is low and wind direction quite constant. The two dimensional shear stress of the wind field and the sand movement by saltation and avalanches over a barchan dune are simulated. The model with one dimensional shear stress is extended including surface diffusion and lateral shear stress. The resulting final shape is compared to the results of the m...

Singing dunes, which emit a loud sound as they avalanche, constitute a striking and poorly understood natural phenomenon. We show that, on the one hand, avalanches excite elastic waves at the surface of the dune, whose vibration produces the coherent acoustic emission in the air. The amplitude of the sound (approximately 105 dB) saturates exactly when the vibration makes the grains take off the...

In the dunes of the Pouto Peninsula, north Kaipara, Northland, re-mobilised sand is invading remnants of native forest and scrub, and filling dune lakes and swamps. Some of the affected native vegetation is botanically important as remnants of regionally and even nationally rare plant communities and as the habitats of threatened plant species. The wetlands are important waterbird habitats. At ...

Wind erosion is considered a major global environmental problem. Dust storms from the migration of sand dunes can seriously damage civil, industrial, and agricultural areas and a method to stabilize these sand dunes is mulching. The present study investigates the feasibility of using organic wastes of Press mud and Dunder with clay for the production of environmentally-friendly mulches. Sandy s...

introduction: wind erosion is one of the most important factors in desert environments. prevailing winds can shift sand dunes and affect their accumulation and morphology. also, wind regime determines the direction of sand dune mobility in different ways. therefore, the wind regime, frequency, direction and velocity are supposed to be the most important factors to form the morphology of sand du...

Introduction: The OMEGA instrument on Mars Express has recently detected the largest gypsum deposit on Mars within the north polar sand sea [1]. Here we discuss the unique geologic context and origin of this evaporite deposit. Gypsum on Earth and Mars: Gypsum is a hydrated Ca-sulfate (2H 2 O • CaSO 4). Though gypsum can be formed, for example, as a hydrothermal deposit [e.g., 2] or as an altera...