Climate change has led to warmer and wetter conditions in Nova Scotia, leading to more frequent and intense rainfall events and sea level rise. This has resulted in increased coastal flooding where the Salmon River meets the North River, negatively impacting coastal communities such as Truro and Colchester.
The scope and causes of the increased flooding were analyzed in a risk assessment by CBCL Limited, an engineering firm. This began with field data collection where the ground topography and river bathymetry were surveyed. Tipping bucket rain gauges were installed in 2014 to monitor rainfall, water level gauges were installed at the Salmon River, North River, and McClure’s brook to monitor tide levels and sediment samples were collected from five locations. Data collected was used in a range of hydraulic, two-dimensional, and three-dimensional models and geographic computer tools to estimate impacts. CBCL further projected possible flood risks up till 2100. They marked the area around the river banks in three categories – Floodway, Floodway 1:20 and Floodway 1:100. 1:20 identified the probability that floodwater reached the mark once in the next 20 years and 1:100 identified the probability for 100 years. This helped demarcate areas of higher and lower risk.
A Social Vulnerability Assessment was undertaken to determine how different regional populations were at risk of flooding and other related hazards. Through an analysis that utilized the Canada Index of Multiple Deprivation for the area, it was revealed that the variables of Residential Instability and Economic Dependency in Truro had significantly higher values than those for the Onslow side of the river. This was related to factors such as a higher number of senior residents, a larger number of homes needing repair, and a more significant number of residents living at home. Factors such as these affect the population’s ability to respond to and cope with hazards such as flooding, which helps determine how best to support them in adaptation.