Air and Sand Movements to the Lee of DUNES1

摘要: SUMMARY The large and extensive transverse barchane dunes of coastal South West Africa are strongly oriented under the influence predominantly southerly winds. During periods strong winds (40–50 miles/h) deposition occurs on lee slope in three ways: (1) sand is blown over crest dune falls slope; (2) rapid near results periodic slumps slides down (3) eddy currents developed to pick up from surface downwind transport it slope. The size strength surprising. With 40–50 miles/h range frequent gusts lift fine a height several feet. Less frequently picked low position redeposited higher slope. The addition material by much less volumetrically than contribution directly windward direction; however, with removal transportation area back appears be important deflation this surface. width influenced during about equal dune. Observations 1 20 ft. high at Sapelo Island, Ga., U.S.A., confirm presence well these moderate (20–50 miles/h).