MONITORING OF PHYSICAL CHANGES ASSOCIATED WITH THE OPENING OF THE GATES AT THE PETITCODIAC RIVER CAUSEWAY, MONCTON, NB

摘要

The 60 km Petitcodiac estuary in southeastern New Brunswick is characterized by some of the highest tides and suspended sediment loadings in the world. In 1968 a causeway was completed across the estuary severing the upper 22.5 km from tidal influence. The tidal prism was reduced by 25 million m and massive siltation occurred downstream, reducing the tidal prism by a further 140 million m~3 by 2002. In 2005 a major study recommended breaching the causeway to restore full tidal exchange. In 2010 the causeway control gates were opened allowing tidal exchange. Physical monitoring of the estuary for a period of two years has been undertaken to assess the response in terms of that predicted in the 2005 study. In the first year, erosion downstream has been about 19 million m~3. The erosion rate is about four times that predicted but the locations of maximum erosion are generally in agreement with the 2005 predictions. Most of the eroded material is being deposited in the area where it likely originated, the Upper Bay of Fundy.