a study on isatis suspension trap efficiency; advantages and disadvantages

different types of sediment trap have been introduced so far to be used in erosion measuring stations, each with its own advantages and disadvantages in trapping aeolian particles. these traps have different collection and retention efficiency due to aerodynamic conditions. some characteristics such as isokinetic feature of the trap, collection efficiency, time needed to download sediment, capability of installation in different altitudes and capability to collect sediment from different geographical directions are the criteria used to assess the efficiency of different types of sediment traps. in the present study isatis suspension trap (isatis sustra) was tested in a wind tunnel and wind erosion measuring station. this is a kind of passive trap and its sediment collecting efficiency varies between 55% to 88% for 5 to 9 m/s velocities respectively in the height of 15cm. although the efficiency of the trap in low wind velocities is less than 55%, it is remarkable comparing with other traps. larger mouth of the trap provides it with vaster opportunity to trap sediment. isatis sustra has the capability to segregate sediments in different geographical directions. this privilege leads to 1) possibility to analyze horizontal distribution in different geographical directions, 2) determining the most sediment producing fraction and easy recognition of the source, 3) estimating moved materials such as dissolved salts or heavy elements in mine range) through separating sediment samples and 4) easy installation in different altitudes and enough capacity to reserve aeolian sediment. generally speaking, the results from indoor and outdoor tests indicate that isatis sustra has appropriate capabilities with regard to collecting efficiency, keeping, sediment reserve capacity and easy download in hard conditions.