Wind tunnel experiments and field measurements of aeolian dust deposition on conical hills

The spatial pattern of short-term aeolian dust deposition on and around cone-shaped hills is investigated via the simulation, in a wind tunnel, of dust storms over a topographic scale model of a conical hill in the Negev desert, Israel. The results are tested during a full-scale dust storm in the Negev. The wind tunnel experiments adequately predict the field pattern, although some problems may arise on steep windward slopes where the accumulation threshold is more quickly exceeded on the scale model than in the field. Conical hills create an elongated area of low deposition (“dust shadow”) in their lee. Downwind from the shadow zone, a local area of more-than-normal (compared to the undisturbed surroundings) deposition occurs. On the lateral flanks of the hill, and also on the small convex windward slope just upstream of the top (and at the top itself), dust deposition remains low to very low. It is the lowermost, concave windward slope that receives the largest amounts of dust. ttern described above refers to short-term deposition only. Water erosion may seriously alter the final accumulation pattern since it will clean the slopes of important amounts of dust that accumulate in the wadis.