Dry aeolian dust accumulation in rocky deserts: A medium-term field experiment based on short-term wind tunnel simulations

The spatial pattern of medium-term (a few months) dry aeolian dust accumula tion in rocky deserts is predicted using shortterm deposition and erosion e xperiments in a wind tunnel. The predictions ape tested in a field experime nt set up in the northern Negev Desert of Israel. The results show that sup erimposing wind tunnel deposition and erosion maps usually leads to correct predictions of medium-term dust accumulation. The predictions are somewhat less confident near the inflection lines of windward hillslopes, where sma ll-scale irregularities in the local topography make it difficult to locate the exact position of the areas of little accumulation. Elsewhere in the t opography predictions are good, and the method works satisfactorily. Highest accumulation occurs on concave windward slopes and, to a lesser ext ent, on slopes parallel to the wind. Little accumulation occurs on the conv ex windward slopes and in dust separation bubbles. The smallest accumulatio n rates are observed immediately upwind of the top of pronounced hills and on leeslopes. The rate of dry dust accumulation measured during the field experiment vari ed from 17 to 93 g m(-2) a(-1) depending on the topographic position of the accumulation plots. for most plots, it was of the order of 30-60 g m(-2) a (-1). Copyright (C) 2000 John Wiley & Sons, Ltd.