A comparative study on the use of Passive Integrated Transponders to estimate sediment transport: first results

Sediment transport is of fundamental importance to river dynamics. Tracers are frequently used to characterize this process but existing techniques are subject to a number of limitations that result in low recovery percentages. The use of Passive Integrated Transponders (PITs) has been shown to be more effective than other techniques, but this methodology has not yet been tested in larger rivers and over longer time periods. This article presents results from two independent tests in different sized rivers. In the smaller watercourse (6 m wide) we obtained recovery percentages between 87 to 90 % during four surveys of their positions. There was no decrease in recovery percentage with time. An analysis of the sources of error indicates that the majority of missing particles were buried deeper than the approximately 25 cm detection range in the bed. In the larger watercourse (100 m wide), the recovery percentage was 36 % after one year. This percentage while less than that obtained in the smaller watercourse is still much higher than other tachniques for this size of watercourse. Sources of error likely include particle burial in large banks and an inability to measure in deep pools. The use of PIT tags priovides detailed spatial information of particle movements and has superior recovery percentages than other sediment tracking methos in gravel-bed rivers.