Shoreline armouring on the north shore of mainland Nova Scotia

Abstract

Using Google Earth (GE) and ground proofing of selected shorelines, we mapped coastal defense measures (CDMs), along the coast of the Northumberland Strait of Nova Scotia from the New Brunswick border to the Canso Causeway. An initial method used 256 point samples from Tidnish to Cape George at 0.5’ of longitude and revealed a 22.8% occurrence of armouring. A second method used GE images and the ‘path’ tool to trace the lengths of each individual wall along 15 shoreline segments facing the Northumberland Strait and selected bays and estuaries. This identified 218 individual CDMs with the most frequent 51-150 m long and four continuous walls over 1000 m long. Shores had 3% to 74% armouring with enclosed estuaries generally having lower values and the outer, exposed shores having higher values. Short lengths of armouring (i.e., less than 50 m) were generally associated with individual residential properties. The impacts of CDMs are discussed in relation to coastal and vegetation changes on shorelines of northern Nova Scotia. Several case studies including original observations at Northport, Big Island, and Mahoneys Island demonstrate for the first time in eastern Canada how CDMs have modified coastal habitats, specifically sand dune and salt marsh ecosystems.

Keywords: armouring, beaches, climate change, sea-level rise, seashore erosion