Sediment Tracking Throughout the Winter and Spring Breakup in a Gravel-bed River

English Abstract:

A field study was conducted on two different reaches of a gravel-bed river (Stoke River) located in the Eastern Townships, Québec, Canada. The study was performed to quantitatively assess the mobility of the bed sediments due to ice. At both sites, PIT tags were placed in the river bed and were tracked via a dual antenna system. Fixed antennas were placed in the river bed and were connected to a data logger in order to follow the tagged particles over the winter and spring breakup. To complement this system surveys were made with a mobile antenna in order to measure the exact movement of the particles. The redundancy of our methodology was useful to overcome the difficulties of surveying tagged particles during winter time. This was especially effective during the spring thaw, at a time where most rivers are too active to be surveyed. The fixed antenna recorded, though not as precisely as the mobile antenna, the time of arrival and departure of each moving marker. After the water level decline, surveys with the mobile antenna were performed to record the precise location and 3D displacement of the marker. The only downfall of the fixed antenna system is in order to gain more precision (denser grid), a denser fixed antenna system is required, along with a higher number of equipment (batteries, loggers, antennas, etc.) which are difficult to maintain at a sufficient power level during winter time.