TESTING THE USE OF RFID (RADIO FREQUENCY IDENTIFICATION) IN STUDYING TRANSPORT OF GRAVEL BY THE MILL RIVER ON SMITH COLLEGE CAMPUS IN NORTHAMPTON, MASSACHUSETTS

Radio Frequency Identification (RFID) technology that utilizes small Passive Integrative Transponder (PIT) tags has been developed to monitor wildlife, but has recently also been applied in studying sediment transport in fluvial environments. This work aims to test the use of RFID in monitoring gravel transport by the Mill River on Smith College Campus. The first stage of the project focuses on a small mid-river gravel bar (~3 m wide, 8 m long) downstream from the Paradise Pond dam and the pedestrian Lamont Bridge.

This bar is heavily vegetated, suggesting that its gravel does not move frequently, which is also supported by a thick dark patina on most individual clasts. A substantial portion of the gravel in this area consists of relatively large (up to ~25 cm in diameter) angular basalt pieces, which were likely dumped during the construction of the dam, the bridge and the nearby flood-control levee. Thus, even though this gravel bar is not very mobile and has been anthropogenically impacted, it was chosen for the initial stage of this research due to its convenient location and easy access. Transverse and longitudinal transects across the bar are being constructed, high-resolution drone imagery has been acquired, and four PIT tags (23 mm long and <4 mm in diameter) have been inserted in mainly granitic, rounded pebbles, ranging in size from 7 to 13 cm in diameter and weighing 0.4 to 1.8 kg. The small bar size precludes the use of many additional tags due to potential interference. The tagged pebbles will be relocated after major future high-flow events to evaluate the hypotheses regarding the mobility of this bar.

The second stage of the project will focus on a point bar upstream from Paradise Pond, utilizing the same methodology, but allowing for more extensive tagging of this more natural and mobile gravel deposit due to its larger size and greater abundance and diversity of relatively fresh pebbles. The ultimate goal of this project is to set the stage for long-term monitoring of gravel transport within the larger scale interdisciplinary Mill River Watershed Assessment Project. Understanding how sediment is transported by the Mill River through and beyond the Smith College Campus is becoming increasingly important as frequency and intensity of storms and flooding are predicted to increase as a result of ongoing climate changes.