We investigate theoretically the nonlinear evolution of sand ripples in a viscous fluid when a granular bed is submitted to a two-dimensional laminar shear flow. On the basis of the hydrodynamic equations and a semi-empirical sand transport law, we derive a non-local and nonlinear equation for the dynamics of the bed profile in the case of infinite flow depth. This equation reveals a coarsening...

– From the observation of a convection flow in a single layer of vertically vibrated sand, we conclude that the amplitude gradient of the vibrating bed, which is naturally expected but often neglected, can be crucial for the same phenomenon in containers with more sand. A simple model is proposed to explain the dependence of the drift velocity on the vibration amplitude and frequency. The conve...

Sand is a key material foundation of modern cities. In Hong Kong, city founded in British mercantile imperialism, the extraction sand needed for construction and reclamation projects has always been tied up with violent dispossession. Experimenting forms poetics postcolonial new materialist critical theory, thinking sand’s distinctive materialities drift, this paper develops speculative critiqu...

Atlantic Salmon (Salmo salad redds were exanuned in t.he upperSusqueherma River during November of 1992 and 1993 at Cooperstown, W{, In 1993, ten redds were composed of 10% boulder, 12% cobble, 52% pebble, 18% gravel and 8% sand. Five redds in 1992 had a composition of 42% cobble, 36% gravel and 10% sand. Fish were sampled with a fine rnesh drift net to provide ages, lengths, weights and sex. A...

Wind-shield walls decrease the velocity of wind-drift sand flow in transit. This results in sand accumulating in the wind-shadow zone of both windshield wall and track line, causing severe sand sediment hazard. This study reveals the characteristics of sand accumulation and the laws of wind-blown sand removal in the wind-shadow areas of three different types of windshield walls, utilizing three...

Erosion of the southern Gold Coast beaches (SE Queensland, Australia) was exacerbated after the extension of the Tweed River training walls in the early 1960s. To achieve the objective of restoring and maintaining beach amenity, significant nourishment works have been undertaken in Coolangatta Bay over the past 30 years. Particularly, under the Tweed River Entrance Sand Bypassing Project (TRESB...