Morphologic characteristics and development of falling dunes, northeast Kuwait

Falling dunes are the most common aeolian landform in northeast Kuwait. They are associated with the Jal Az-Zor escarpment. Comparison of aerial photographs from 1972 and 1992 indicates that these dunes developed recently. This change in a relatively short period is attributable mainly to drought, intensive land use and availability of sand source linked to surface disturbance. Military activities during the two Gulf wars are the main cause of surface disturbance. The variability in morphology of falling dunes along the dissected escarpment is related to local microtopographic, morphologic and hydrologic characteristics. The length of the falling dunes ranges from 38 to 383 m and their width from 7 to 85 m. They attain a maximum height of 10 m from ground surface. To discuss the wind energy environment of the study area, Fryberger method was used. The results indicate that falling dunes developed under a high-energy environment, in particular during summer (June–August) when the drift potential (DP) is relatively higher and wind direction has low variability. Numerical computations using FLUENT 6.0 were employed to simulate both the airflow over the escarpment in 2D with slope angles of 15°, 45° and 90° and the airflow within the vicinity of the valley in 3D. The results indicate that development of falling dunes is significantly affected by slope angle. Steep slope angle favors the development of falling dunes due to the reduction of wind velocity in the wake zone downwind of the escarpment.