A new ‘pressure sensitive’ method of measuring aeolian sediment transport using a Gauged Sediment Trap (GaST)

Abstract

This paper describes the construction and application of a new field instrument, a Gauged Sediment Trap (GaST). Our GaST measures and captures aeolian-transported sediment, can be deployed for long periods of time (weeks), is easy to construct, and is extremely durable. The instrument consists of a water-level logger contained within an underground, water-filled sleeve, into which sediment is funneled from a surface trap. As sediment enters the sleeve water is displaced proportionally to the volume of sediment allowing for continuous monitoring of sediment accumulation. The rate of sediment transport and flux, for a given time period, is estimated through laboratory calibration using sediment from the study area and the GaST. The instrument can be affixed to almost any surface-sediment trap, whether saltation or bedload transport is the target. Data from laboratory calibration and several field tests staged in the summer and winter on Bogue Banks, NC, are presented. Using the HOBO® U20 Water-Level Logger, the GaST accurately captured sediment transport at a resolution of 5.71 g (2.15 cm 3) of sediment per unit time, depending on sampling interval and overall sediment flux. The GaST predicted total sediment mass and volumes with less than 5% error. With an adjustable sampling interval, the GaST can be deployed for various lengths of time but may be limited by the rate of sediment accumulation (they can overflow) and the evaporation rate inside the sleeve (the water could completely evaporate in arid settings).