An omnidirectional vertical sand trap is described for use in the meas
urement of sand transported by wind in the dune environment. In the fi
eld these traps yielded good results. The traps were calibrated by com
paring them with a Bagnold trap of known efficiency and by wind tunnel
experiments. Efficiency of the trap was not constant, being dependent
on the wind speed, the grain-size distribution of the sediment and th
e moisture content. The calibration resulted an efficiency of between
15 and 20%. The highest efficiencies were observed for wind speeds of
8 m/s. For lower wind speeds the efficiency decreased because of the i
ncreasing importance of creep. With higher wind speeds the efficiency
was reduced because of an increasing loss by blowout.