Geological Survey of Canada
Impact of storms
Hurricane Juan (September 29, 2003)
Martinique Beach, Nova Scotia
Introduction
Martinique Beach is located 50 km east of Halifax between Petpeswick Inlet and Musquodoboit Harbour. The beach is 3.5 km long and consists of a gradual sloping sand foreshore backed by a single primary dune ridge in the backshore.
Aerial view of Martinique Beach from 1976 (By R. Belanger, BIO) showing the location of eight cross-shore survey lines. Following Hurricane Juan, cross-shore surveys were completed at lines 1 to 4 and across the breach formed in1998 at line 6. Lines 1 to 3 had not been surveyed since June 1999.The most obvious impacts of Hurricane Juan were damage by wind, waves and flooding to park infrastructure such as boardwalks, washroom and picnic facilities. The backshore dune was scarped in many places and/or its vegetation was trimmed, rolled back and flattened by wave runup. Dune erosion was greatest where walking paths crossed the dune to the beach or where larger pieces of flotsam had been deposited against the dune face. Waves were funneled upslope carving out sides of paths and larger pieces of flotsam focussed wave scour on the duneface.
View of Martinique Beach near parking lot 2 where waves flooded and trimmed the lower seaward dune built since 1999, deposited cobbles, scoured the old duneline and damaged the access steps. The flood debris line at 3.2 m elevation is marked by an arrow.
Cross-shore profile: An example beach changes resulting from hurricane Juan at Line 2 Martinique Beach. The upper beach was scoured but there was little net change to the duneline since 1999.
View looking west at Line 2 Martinique Beach in June 11, 1999 showing the spread of new vegetation at the base of the established duneline
View looking west at Line 2 Martinique Beach in October 3, 2003 showing the consequence of hurricane Juan which scoured the upper beach and new dune and trimmed back the established duneline.
At Line 4 waves extended up and over the dune crest which was at an elevation of 5.1 m. The blue line represents a survey in April 2003 and the black line the post- hurricane Juan survey on Oct. 3, 2003. The only significant change across the beach was sediment accretion across the lower intertidal zone.(see photos below)
View of Martinique Beach at line 4 in April 2003 showing the post winter conditions.
View of line 4, Martinique Beach on October 3, 2003 after hurricane Juan. The duneline, with its flattened vegetation and trim line is similar in appearance to the post-winter conditions shown above.1998 Barrier Breach Site:
Photographs and an east-west survey across the breach revealed some of the changes at the breach which had been slowly building with sand since February 1998 when the breach was formed. Flotsam lines from hurricane Juan reached 2.5 m elevation along the adjacent duneline .
Repetitive surveys across the 1998 breach revealed a variable net change of less than +/- 0.3 m since April 2003. The breach was overwashed by waves and some sediment which had accumulated since April was carried landward to the lagoon but the vegetation had retained most of the material. The first survey completed in June 1999 is included to show the net increase in sand levels during the past four years at the west end of the breach where the main washover channel was formed in 1998
Repetitive views of the mouth of a wide breach which was cut through Martinique Beach in February 1998. A) showing post-winter conditions on April 14, 2003.
1998 Breach on July 31, 2003 showing sand accumulation and a spread of dune grass since April, 2003.
1998 Breach, October 9, 2003 after hurricane Juan when waves overwashed and partially buried the vegetation. The grass will survive and regrow next season if winter storms are not too severe.
